diff --git a/pkg/analyzer/test/generated/strong_mode_test.dart b/pkg/analyzer/test/generated/strong_mode_test.dart
index f54f907efe9..323ccac5223 100644
--- a/pkg/analyzer/test/generated/strong_mode_test.dart
+++ b/pkg/analyzer/test/generated/strong_mode_test.dart
@@ -78,7 +78,7 @@ class StrongModeLocalInferenceTest extends PubPackageResolutionTest {
   }
 
   test_async_method_propagation() async {
-    String code = r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
       class A {
         Future f0() => new Future.value(3);
         Future f1() async => new Future.value(3);
@@ -96,8 +96,7 @@ class StrongModeLocalInferenceTest extends PubPackageResolutionTest {
         Future<int> g4() async { return new Future.value(3); }
         Future<int> g5() async { return await new Future.value(3); }
       }
-   ''';
-    var result = await resolveTestCode(code);
+   ''');
 
     void check(String name, Asserter<InterfaceType> typeTest) {
       MethodDeclaration test = AstFinder.getMethodInClass(
@@ -139,7 +138,7 @@ class StrongModeLocalInferenceTest extends PubPackageResolutionTest {
   }
 
   test_async_propagation() async {
-    String code = r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
       Future f0() => new Future.value(3);
       Future f1() async => new Future.value(3);
       Future f2() async => await new Future.value(3);
@@ -155,8 +154,7 @@ class StrongModeLocalInferenceTest extends PubPackageResolutionTest {
       Future<int> g3() { return new Future.value(3); }
       Future<int> g4() async { return new Future.value(3); }
       Future<int> g5() async { return await new Future.value(3); }
-   ''';
-    var result = await resolveTestCode(code);
+   ''');
 
     void check(String name, Asserter<InterfaceType> typeTest) {
       FunctionDeclaration test = AstFinder.getTopLevelFunction(
@@ -197,16 +195,17 @@ class StrongModeLocalInferenceTest extends PubPackageResolutionTest {
   }
 
   test_cascadeExpression() async {
-    String code = r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
       class A<T> {
         List<T> map(T a, List<T> mapper(T x)) => mapper(a);
       }
 
       void main () {
         A<int> a = new A()..map(0, (x) => [x]);
-     }
-   ''';
-    var result = await resolveTestCode(code);
+//             ^
+// [diag.unusedLocalVariable] The value of the local variable 'a' isn't used.
+      }
+   ''');
     List<Statement> statements = AstFinder.getStatementsInTopLevelFunction(
       result.unit,
       "main",
@@ -5743,7 +5742,7 @@ class C extends Override implements Base {}
   }
 
   test_localVariableInference_bottom_disabled() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 main() {
   var v = null;
   v; // marker
@@ -5753,7 +5752,7 @@ main() {
   }
 
   test_localVariableInference_constant() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 main() {
   var v = 3;
   v; // marker
@@ -5763,7 +5762,7 @@ main() {
   }
 
   test_localVariableInference_declaredType_disabled() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 main() {
   dynamic v = 3;
   v; // marker
@@ -5773,7 +5772,7 @@ main() {
   }
 
   test_localVariableInference_noInitializer_disabled() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 main() {
   var v;
   v = 3;
@@ -5802,7 +5801,7 @@ AssignmentExpression
   }
 
   test_localVariableInference_transitive_field_inferred_lexical() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   final x = 3;
   f() {
@@ -5818,7 +5817,7 @@ main() {
   }
 
   test_localVariableInference_transitive_field_inferred_reversed() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   f() {
     var v = x;
@@ -5834,7 +5833,7 @@ main() {
   }
 
   test_localVariableInference_transitive_field_lexical() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   int x = 3;
   f() {
@@ -5850,7 +5849,7 @@ main() {
   }
 
   test_localVariableInference_transitive_field_reversed() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   f() {
     var v = x;
@@ -5866,7 +5865,7 @@ main() {
   }
 
   test_localVariableInference_transitive_list_local() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 main() {
   var x = <int>[3];
   var v = x[0];
@@ -5877,7 +5876,7 @@ main() {
   }
 
   test_localVariableInference_transitive_local() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 main() {
   var x = 3;
   var v = x;
@@ -5888,7 +5887,7 @@ main() {
   }
 
   test_localVariableInference_transitive_topLevel_inferred_lexical() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 final x = 3;
 main() {
   var v = x;
@@ -5900,7 +5899,7 @@ main() {
   }
 
   test_localVariableInference_transitive_toplevel_inferred_reversed() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 main() {
   var v = x;
   v; // marker
@@ -5912,7 +5911,7 @@ final x = 3;
   }
 
   test_localVariableInference_transitive_topLevel_lexical() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 int x = 3;
 main() {
   var v = x;
@@ -5924,7 +5923,7 @@ main() {
   }
 
   test_localVariableInference_transitive_topLevel_reversed() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 main() {
   var v = x;
   v; // marker
diff --git a/pkg/analyzer/test/src/dart/ast/element_locator_test.dart b/pkg/analyzer/test/src/dart/ast/element_locator_test.dart
index 9044fffabdd..b384ad20573 100644
--- a/pkg/analyzer/test/src/dart/ast/element_locator_test.dart
+++ b/pkg/analyzer/test/src/dart/ast/element_locator_test.dart
@@ -22,9 +22,11 @@ main() {
 @reflectiveTest
 class ElementLocatorTest2 extends PubPackageResolutionTest {
   test_locate_AssignedVariablePattern() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void f() {
   int foo;
+//    ^^^
+// [diag.unusedLocalVariable] The value of the local variable 'foo' isn't used.
   (foo, _) = (0, 1);
 }
 ''');
@@ -36,7 +38,7 @@ foo@17
   }
 
   test_locate_AssignmentExpression() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 int x = 0;
 void main() {
   x += 1;
@@ -50,7 +52,9 @@ dart:core::@class::num::@method::+
   }
 
   test_locate_BinaryExpression() async {
-    var result = await resolveTestCode('var x = 3 + 4');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+var x = 3 + 4;
+''');
     var node = result.findNode.binary('+');
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -59,9 +63,11 @@ dart:core::@class::num::@method::+
   }
 
   test_locate_CatchClauseParameter() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void f() {
   try {} catch (e, s) {}
+//                 ^
+// [diag.unusedCatchStack] The stack trace variable 's' isn't used and can be removed.
 }
 ''');
     var node = result.findNode.catchClauseParameter('e');
@@ -77,7 +83,9 @@ s@30
   }
 
   test_locate_ClassDeclaration() async {
-    var result = await resolveTestCode('class A {}');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+class A {}
+''');
     var node = result.findNode.classDeclaration('class');
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -86,7 +94,7 @@ s@30
   }
 
   test_locate_ConstructorDeclaration_named() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   A.foo();
 }
@@ -99,7 +107,7 @@ class A {
   }
 
   test_locate_ConstructorDeclaration_unnamed() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   A();
 }
@@ -112,7 +120,7 @@ class A {
   }
 
   test_locate_ConstructorSelector_EnumConstantArguments_EnumConstantDeclaration() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 enum E {
   v.named(); // 0
   const E.named();
@@ -126,9 +134,11 @@ enum E {
   }
 
   test_locate_DeclaredVariablePattern() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void f(Object? x) {
   if (x case int foo) {}
+//               ^^^
+// [diag.unusedLocalVariable] The value of the local variable 'foo' isn't used.
 }
 ''');
     var node = result.findNode.declaredVariablePattern('foo');
@@ -139,11 +149,13 @@ foo@37
   }
 
   test_locate_DotShorthandConstructorInvocation() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {}
 
 void main() {
  A a = .new();
+// ^
+// [diag.unusedLocalVariable] The value of the local variable 'a' isn't used.
 }
 ''');
     var node = result.findNode.singleDotShorthandConstructorInvocation;
@@ -154,13 +166,15 @@ void main() {
   }
 
   test_locate_DotShorthandInvocation() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   static A foo() => A();
 }
 
 void main() {
  A a = .foo();
+// ^
+// [diag.unusedLocalVariable] The value of the local variable 'a' isn't used.
 }
 ''');
     var node = result.findNode.singleDotShorthandInvocation;
@@ -171,13 +185,15 @@ void main() {
   }
 
   test_locate_DotShorthandPropertyAccess() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   static A foo = A();
 }
 
 void main() {
  A a = .foo;
+// ^
+// [diag.unusedLocalVariable] The value of the local variable 'a' isn't used.
 }
 ''');
     var node = result.findNode.singleDotShorthandPropertyAccess;
@@ -188,7 +204,9 @@ void main() {
   }
 
   test_locate_DottedName_libraryDirective() async {
-    var result = await resolveTestCode('library foo.bar;');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+library foo.bar;
+''');
     var node = result.findNode.singleDottedName;
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -197,7 +215,7 @@ void main() {
   }
 
   test_locate_EnumConstantDeclaration() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 enum E {
   one
 }
@@ -210,7 +228,9 @@ enum E {
   }
 
   test_locate_ExportDirective() async {
-    var result = await resolveTestCode("export 'dart:core';");
+    var result = await resolveTestCodeWithDiagnostics(r'''
+export 'dart:core';
+''');
     var node = result.findNode.export('export');
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -219,7 +239,9 @@ dart:core
   }
 
   test_locate_ExtensionDeclaration() async {
-    var result = await resolveTestCode('extension A on int {}');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+extension A on int {}
+''');
     var node = result.findNode.singleExtensionDeclaration;
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -228,7 +250,9 @@ dart:core
   }
 
   test_locate_ExtensionTypeDeclaration() async {
-    var result = await resolveTestCode('extension type A(int it) {}');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+extension type A(int it) {}
+''');
     var node = result.findNode.singleExtensionTypeDeclaration;
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -237,9 +261,11 @@ dart:core
   }
 
   test_locate_FunctionDeclaration_local() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void f() {
   int g() => 3;
+//    ^
+// [diag.unusedElement] The declaration 'g' isn't referenced.
 }
 ''');
     var node = result.findNode.functionDeclaration('g');
@@ -250,7 +276,9 @@ g@17
   }
 
   test_locate_FunctionDeclaration_topLevel() async {
-    var result = await resolveTestCode('int f() => 3;');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+int f() => 3;
+''');
     var node = result.findNode.functionDeclaration('f');
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -259,7 +287,7 @@ g@17
   }
 
   test_locate_Identifier_annotationClass_namedConstructor() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class Class {
   const Class.name();
 }
@@ -273,7 +301,7 @@ void main(@Class.name() parameter) {}
   }
 
   test_locate_Identifier_annotationClass_unnamedConstructor() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class Class {
   const Class();
 }
@@ -287,7 +315,9 @@ void main(@Class() parameter) {}
   }
 
   test_locate_Identifier_className() async {
-    var result = await resolveTestCode('class A {}');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+class A {}
+''');
     var node = result.findNode.classDeclaration('A');
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -296,7 +326,7 @@ void main(@Class() parameter) {}
   }
 
   test_locate_Identifier_constructor_named() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   A.bar();
 }
@@ -309,7 +339,7 @@ class A {
   }
 
   test_locate_Identifier_constructor_unnamed() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   A();
 }
@@ -322,7 +352,7 @@ class A {
   }
 
   test_locate_Identifier_fieldName() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   var x;
 }
@@ -335,7 +365,7 @@ class A {
   }
 
   test_locate_Identifier_functionCallMethod_invocation() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void f(int a) {
   f.call(a);
 }
@@ -348,7 +378,7 @@ void f(int a) {
   }
 
   test_locate_Identifier_functionCallMethod_tearOff() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void f(int a) {
   f.call;
 }
@@ -361,9 +391,11 @@ void f(int a) {
   }
 
   test_locate_Identifier_propertyAccess() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void main() {
  int x = 'foo'.length;
+//   ^
+// [diag.unusedLocalVariable] The value of the local variable 'x' isn't used.
 }
 ''');
     var node = result.findNode.simple('length');
@@ -374,7 +406,9 @@ dart:core::@class::String::@getter::length
   }
 
   test_locate_ImportDirective() async {
-    var result = await resolveTestCode("import 'dart:core';");
+    var result = await resolveTestCodeWithDiagnostics(r'''
+import 'dart:core';
+''');
     var node = result.findNode.import('import');
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -383,10 +417,12 @@ dart:core
   }
 
   test_locate_IndexExpression() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void main() {
   var x = [1, 2];
   var y = x[0];
+//    ^
+// [diag.unusedLocalVariable] The value of the local variable 'y' isn't used.
 }
 ''');
     var node = result.findNode.index('[0]');
@@ -399,7 +435,7 @@ MethodMember
   }
 
   test_locate_InstanceCreationExpression() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {}
 
 void main() {
@@ -417,7 +453,7 @@ void main() {
     newFile('$testPackageLibPath/a.dart', r'''
 class A {}
 ''');
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 import 'a.dart' as pref;
 
 void main() {
@@ -434,7 +470,7 @@ package:test/a.dart::@class::A::@constructor::new
   test_locate_InstanceCreationExpression_type_simpleIdentifier() async {
     newFile('$testPackageLibPath/a.dart', r'''
 ''');
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {}
 
 void main() {
@@ -449,7 +485,9 @@ void main() {
   }
 
   test_locate_LibraryDirective() async {
-    var result = await resolveTestCode('library foo;');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+library foo;
+''');
     var node = result.findNode.library('library');
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -458,7 +496,9 @@ void main() {
   }
 
   test_locate_LibraryElement() async {
-    var result = await resolveTestCode('// only comment');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+// only comment
+''');
 
     var element = ElementLocator.locate(result.unit);
     _assertElement(element, r'''
@@ -467,7 +507,7 @@ void main() {
   }
 
   test_locate_MethodDeclaration() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   void foo() {}
 }
@@ -480,7 +520,7 @@ class A {
   }
 
   test_locate_MethodInvocation_class_callMethod_argument() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   void call(int i) {}
 }
@@ -496,7 +536,7 @@ void f(A a) {
   }
 
   test_locate_MethodInvocation_class_callMethod_constructor() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   void call(int i) {}
 }
@@ -512,7 +552,7 @@ void f() {
   }
 
   test_locate_MethodInvocation_function_callMethod_invocation() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void f(int i) {
   f.call(1);
 }
@@ -525,7 +565,7 @@ void f(int i) {
   }
 
   test_locate_MethodInvocation_function_callMethod_tearOff() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void f(int i) {
   f.call;
 }
@@ -538,7 +578,7 @@ void f(int i) {
   }
 
   test_locate_MethodInvocation_method() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   void foo() {}
 }
@@ -555,7 +595,7 @@ void main() {
   }
 
   test_locate_MethodInvocation_topLevel() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 foo(x) {}
 
 void main() {
@@ -570,7 +610,9 @@ void main() {
   }
 
   test_locate_MixinDeclaration() async {
-    var result = await resolveTestCode('mixin A {}');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+mixin A {}
+''');
     var node = result.findNode.singleMixinDeclaration;
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -579,7 +621,7 @@ void main() {
   }
 
   test_locate_PatternField() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void f(Object? x) {
   if (x case int(isEven: true)) {}
 }
@@ -592,7 +634,9 @@ dart:core::@class::int::@getter::isEven
   }
 
   test_locate_PostfixExpression() async {
-    var result = await resolveTestCode('int addOne(int x) => x++;');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+int addOne(int x) => x++;
+''');
     var node = result.findNode.postfix('x++');
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -601,7 +645,7 @@ dart:core::@class::num::@method::+
   }
 
   test_locate_Prefix() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 import 'dart:math' as math;
 
 math.Random? r;
@@ -614,7 +658,7 @@ math.Random? r;
   }
 
   test_locate_PrefixedIdentifier() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void f(int a) {
   a.isEven;
 }
@@ -627,7 +671,7 @@ dart:core::@class::int::@getter::isEven
   }
 
   test_locate_PrefixedIdentifier_functionCallMethod() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void f(int a) {
   f.call;
 }
@@ -640,7 +684,9 @@ void f(int a) {
   }
 
   test_locate_PrefixExpression() async {
-    var result = await resolveTestCode('int addOne(int x) => ++x;');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+int addOne(int x) => ++x;
+''');
     var node = result.findNode.prefix('++x');
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -649,7 +695,9 @@ dart:core::@class::num::@method::+
   }
 
   test_locate_PrimaryConstructorBody() async {
-    var result = await resolveTestCode('class A() { this { } }');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+class A() { this { } }
+''');
     var node = result.findNode.singlePrimaryConstructorBody;
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -658,7 +706,9 @@ dart:core::@class::num::@method::+
   }
 
   test_locate_PrimaryConstructorDeclaration() async {
-    var result = await resolveTestCode('extension type A(int it) {}');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+extension type A(int it) {}
+''');
     var node = result.findNode.singlePrimaryConstructorDeclaration;
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -667,7 +717,9 @@ dart:core::@class::num::@method::+
   }
 
   test_locate_PrimaryConstructorDeclaration_named() async {
-    var result = await resolveTestCode('extension type A.named(int it) {}');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+extension type A.named(int it) {}
+''');
     var node = result.findNode.singlePrimaryConstructorDeclaration;
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -676,7 +728,9 @@ dart:core::@class::num::@method::+
   }
 
   test_locate_PrimaryConstructorDeclaration_named_atConstructorName() async {
-    var result = await resolveTestCode('extension type A.named(int it) {}');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+extension type A.named(int it) {}
+''');
     var node =
         result.findNode.singlePrimaryConstructorDeclaration.constructorName;
     var element = ElementLocator.locate(node);
@@ -686,7 +740,9 @@ dart:core::@class::num::@method::+
   }
 
   test_locate_PrimaryConstructorDeclaration_namedConstructor_constructorName() async {
-    var result = await resolveTestCode('class A.named() {}');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+class A.named() {}
+''');
     var node =
         result.findNode.singlePrimaryConstructorDeclaration.constructorName;
     var element = ElementLocator.locate(node);
@@ -697,7 +753,9 @@ dart:core::@class::num::@method::+
 
   test_locate_StringLiteral_exportUri() async {
     newFile("$testPackageLibPath/foo.dart", '');
-    var result = await resolveTestCode("export 'foo.dart';");
+    var result = await resolveTestCodeWithDiagnostics(r'''
+export 'foo.dart';
+''');
     var node = result.findNode.stringLiteral('foo.dart');
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -706,7 +764,9 @@ package:test/foo.dart
   }
 
   test_locate_StringLiteral_expression() async {
-    var result = await resolveTestCode("var x = 'abc';");
+    var result = await resolveTestCodeWithDiagnostics(r'''
+var x = 'abc';
+''');
     var node = result.findNode.stringLiteral('abc');
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -716,7 +776,11 @@ package:test/foo.dart
 
   test_locate_StringLiteral_importUri() async {
     newFile("$testPackageLibPath/foo.dart", '');
-    var result = await resolveTestCode("import 'foo.dart';");
+    var result = await resolveTestCodeWithDiagnostics(r'''
+import 'foo.dart';
+//     ^^^^^^^^^^
+// [diag.unusedImport] Unused import: 'foo.dart'.
+''');
     var node = result.findNode.stringLiteral('foo.dart');
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
@@ -725,9 +789,11 @@ package:test/foo.dart
   }
 
   test_locate_VariableDeclaration_Local() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 f() {
   var x = 42;
+//    ^
+// [diag.unusedLocalVariable] The value of the local variable 'x' isn't used.
 }
 ''');
     var node = result.findNode.variableDeclaration('x =');
@@ -738,7 +804,9 @@ x@12
   }
 
   test_locate_VariableDeclaration_TopLevel() async {
-    var result = await resolveTestCode('var x = 42;');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+var x = 42;
+''');
     var node = result.findNode.variableDeclaration('x =');
     var element = ElementLocator.locate(node);
     _assertElement(element, r'''
diff --git a/pkg/analyzer/test/src/dart/constant/evaluation_test.dart b/pkg/analyzer/test/src/dart/constant/evaluation_test.dart
index 6015edff3cb..c8f79332dbd 100644
--- a/pkg/analyzer/test/src/dart/constant/evaluation_test.dart
+++ b/pkg/analyzer/test/src/dart/constant/evaluation_test.dart
@@ -106,7 +106,7 @@ const int x = 'foo';
   }
 
   test_dotShorthand_enum_simple() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 enum E { v1, v2 }
 const E x1 = .v1;
 const E x2 = .v2;
@@ -303,7 +303,7 @@ E
   }
 
   test_enum_enhanced_named() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 enum E<T> {
   v1<double>.named(10),
   v2.named(20);
@@ -343,7 +343,7 @@ E<int>
   }
 
   test_enum_enhanced_unnamed() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 enum E<T> {
   v1<int>(10),
   v2(20),
@@ -398,7 +398,7 @@ E<String>
   }
 
   test_enum_simple() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 enum E { v1, v2 }
 const x1 = E.v1;
 const x2 = E.v2;
@@ -3897,7 +3897,7 @@ const v2 = -v1;
 @reflectiveTest
 mixin ConstantVisitorTestCases on ConstantVisitorTestSupport {
   test_listLiteral_ifElement_false_withElse() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = [1, if (1 < 0) 2 else 3, 4];
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -3909,7 +3909,7 @@ const c = [1, if (1 < 0) 2 else 3, 4];
   }
 
   test_listLiteral_ifElement_false_withoutElse() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = [1, if (1 < 0) 2, 3];
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -3921,7 +3921,7 @@ const c = [1, if (1 < 0) 2, 3];
   }
 
   test_listLiteral_ifElement_true_withElse() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = [1, if (1 > 0) 2 else 3, 4];
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -3933,7 +3933,7 @@ const c = [1, if (1 > 0) 2 else 3, 4];
   }
 
   test_listLiteral_ifElement_true_withoutElse() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = [1, if (1 > 0) 2, 3];
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -3945,7 +3945,7 @@ const c = [1, if (1 > 0) 2, 3];
   }
 
   test_listLiteral_nested() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = [1, if (1 > 0) if (2 > 1) 2, 3];
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -3959,7 +3959,7 @@ const c = [1, if (1 > 0) if (2 > 1) 2, 3];
   }
 
   test_listLiteral_spreadElement() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = [1, ...[2, 3], 4];
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -3971,7 +3971,7 @@ const c = [1, ...[2, 3], 4];
   }
 
   test_mapLiteral_ifElement_false_withElse() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = {'a' : 1, if (1 < 0) 'b' : 2 else 'c' : 3, 'd' : 4};
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -3991,7 +3991,7 @@ const c = {'a' : 1, if (1 < 0) 'b' : 2 else 'c' : 3, 'd' : 4};
   }
 
   test_mapLiteral_ifElement_false_withoutElse() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = {'a' : 1, if (1 < 0) 'b' : 2, 'c' : 3};
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -4011,7 +4011,7 @@ const c = {'a' : 1, if (1 < 0) 'b' : 2, 'c' : 3};
   }
 
   test_mapLiteral_ifElement_true_withElse() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = {'a' : 1, if (1 > 0) 'b' : 2 else 'c' : 3, 'd' : 4};
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -4031,7 +4031,7 @@ const c = {'a' : 1, if (1 > 0) 'b' : 2 else 'c' : 3, 'd' : 4};
   }
 
   test_mapLiteral_ifElement_true_withoutElse() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = {'a' : 1, if (1 > 0) 'b' : 2, 'c' : 3};
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -4050,17 +4050,15 @@ const c = {'a' : 1, if (1 > 0) 'b' : 2, 'c' : 3};
     expect(value.values.map((e) => e.toIntValue()), unorderedEquals([1, 2, 3]));
   }
 
-  @failingTest
   test_mapLiteral_nested() async {
-    // Fails because we're not yet parsing nested elements.
-    var unitResult = await resolveTestCode('''
-const c = {'a' : 1, if (1 > 0) if (2 > 1) {'b' : 2}, 'c' : 3};
+    var unitResult = await resolveTestCodeWithDiagnostics('''
+const c = {'a' : 1, if (1 > 0) if (2 > 1) ...{'b' : 2}, 'c' : 3};
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
     expect(
       result.type,
       unitResult.typeProvider.mapType(
-        unitResult.typeProvider.intType,
+        unitResult.typeProvider.stringType,
         unitResult.typeProvider.intType,
       ),
     );
@@ -4073,7 +4071,7 @@ const c = {'a' : 1, if (1 > 0) if (2 > 1) {'b' : 2}, 'c' : 3};
   }
 
   test_mapLiteral_spreadElement() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = {'a' : 1, ...{'b' : 2, 'c' : 3}, 'd' : 4};
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -4096,7 +4094,7 @@ const c = {'a' : 1, ...{'b' : 2, 'c' : 3}, 'd' : 4};
   }
 
   test_setLiteral_ifElement_false_withElse() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = {1, if (1 < 0) 2 else 3, 4};
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -4108,7 +4106,7 @@ const c = {1, if (1 < 0) 2 else 3, 4};
   }
 
   test_setLiteral_ifElement_false_withoutElse() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = {1, if (1 < 0) 2, 3};
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -4120,7 +4118,7 @@ const c = {1, if (1 < 0) 2, 3};
   }
 
   test_setLiteral_ifElement_true_withElse() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = {1, if (1 > 0) 2 else 3, 4};
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -4132,7 +4130,7 @@ const c = {1, if (1 > 0) 2 else 3, 4};
   }
 
   test_setLiteral_ifElement_true_withoutElse() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = {1, if (1 > 0) 2, 3};
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -4144,7 +4142,7 @@ const c = {1, if (1 > 0) 2, 3};
   }
 
   test_setLiteral_nested() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = {1, if (1 > 0) if (2 > 1) 2, 3};
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -4156,7 +4154,7 @@ const c = {1, if (1 > 0) if (2 > 1) 2, 3};
   }
 
   test_setLiteral_spreadElement() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = {1, ...{2, 3}, 4};
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -4179,9 +4177,11 @@ String abcdef
   }
 
   test_visitAsExpression_instanceOfSameClass() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 const a = const A();
 const b = a as A;
+//        ^^^^^^
+// [diag.unnecessaryCast] Unnecessary cast.
 class A {
   const A();
 }
@@ -4192,7 +4192,7 @@ class A {
   }
 
   test_visitAsExpression_instanceOfSubclass() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 const a = const B();
 const b = a as A;
 class A {
@@ -4343,7 +4343,7 @@ const c = a && true;
   }
 
   test_visitBinaryExpression_and_bool_known_known() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = false & true;
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -4351,7 +4351,7 @@ const c = false & true;
   }
 
   test_visitBinaryExpression_and_bool_known_unknown() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const b = bool.fromEnvironment('y');
 const c = false & b;
 ''');
@@ -4369,7 +4369,7 @@ const c = true && a;
   }
 
   test_visitBinaryExpression_and_bool_unknown_known() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const a = bool.fromEnvironment('x');
 const c = a & true;
 ''');
@@ -4378,7 +4378,7 @@ const c = a & true;
   }
 
   test_visitBinaryExpression_and_bool_unknown_unknown() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const a = bool.fromEnvironment('x');
 const b = bool.fromEnvironment('y');
 const c = a & b;
@@ -4583,7 +4583,7 @@ const c = a || true;
   }
 
   test_visitBinaryExpression_or_bool_known_known() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = false | true;
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -4591,7 +4591,7 @@ const c = false | true;
   }
 
   test_visitBinaryExpression_or_bool_known_unknown() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const b = bool.fromEnvironment('y');
 const c = false | b;
 ''');
@@ -4611,7 +4611,7 @@ const c = true || a;
   }
 
   test_visitBinaryExpression_or_bool_unknown_known() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const a = bool.fromEnvironment('x');
 const c = a | true;
 ''');
@@ -4620,7 +4620,7 @@ const c = a | true;
   }
 
   test_visitBinaryExpression_or_bool_unknown_unknown() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const a = bool.fromEnvironment('x');
 const b = bool.fromEnvironment('y');
 const c = a | b;
@@ -4630,7 +4630,7 @@ const c = a | b;
   }
 
   test_visitBinaryExpression_or_int() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = 3 | 5;
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -4661,8 +4661,12 @@ const c = 3 | false;
   }
 
   test_visitBinaryExpression_questionQuestion_notNull_notNull() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = 'a' ?? 'b';
+//            ^^^^^^
+// [diag.deadCode] Dead code.
+//               ^^^
+// [diag.deadNullAwareExpression] The left operand can't be null, so the right operand is never executed.
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
     expect(result.type, unitResult.typeProvider.stringType);
@@ -4679,7 +4683,7 @@ class C {}
   }
 
   test_visitBinaryExpression_questionQuestion_null_notNull() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = null ?? 'b';
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -4688,7 +4692,7 @@ const c = null ?? 'b';
   }
 
   test_visitBinaryExpression_questionQuestion_null_null() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = null ?? null;
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -4696,7 +4700,7 @@ const c = null ?? null;
   }
 
   test_visitBinaryExpression_xor_bool_known_known() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = false ^ true;
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -4704,7 +4708,7 @@ const c = false ^ true;
   }
 
   test_visitBinaryExpression_xor_bool_known_unknown() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const b = bool.fromEnvironment('y');
 const c = false ^ b;
 ''');
@@ -4713,7 +4717,7 @@ const c = false ^ b;
   }
 
   test_visitBinaryExpression_xor_bool_unknown_known() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const a = bool.fromEnvironment('x');
 const c = a ^ true;
 ''');
@@ -4722,7 +4726,7 @@ const c = a ^ true;
   }
 
   test_visitBinaryExpression_xor_bool_unknown_unknown() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const a = bool.fromEnvironment('x');
 const b = bool.fromEnvironment('y');
 const c = a ^ b;
@@ -4732,7 +4736,7 @@ const c = a ^ b;
   }
 
   test_visitBinaryExpression_xor_int() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const c = 3 ^ 5;
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'c');
@@ -4928,7 +4932,7 @@ double 3.45
   }
 
   test_visitIntegerLiteral_doubleType() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const double d = 3;
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'd');
@@ -5181,7 +5185,7 @@ const y = B(x);
   }
 
   test_visitSimpleIdentifier_dynamic() async {
-    var unitResult = await resolveTestCode('''
+    var unitResult = await resolveTestCodeWithDiagnostics('''
 const a = dynamic;
 ''');
     DartObjectImpl result = _evaluateConstant(unitResult, 'a');
diff --git a/pkg/analyzer/test/src/dart/element/element_test.dart b/pkg/analyzer/test/src/dart/element/element_test.dart
index de806e1d215..83d7dd3c927 100644
--- a/pkg/analyzer/test/src/dart/element/element_test.dart
+++ b/pkg/analyzer/test/src/dart/element/element_test.dart
@@ -35,7 +35,7 @@ class A {
 }
 void f(@A('x') int p) {}
 ''');
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 import 'a.dart';
 main() {
   f(3);
@@ -54,7 +54,7 @@ main() {
 @reflectiveTest
 class FieldElementImplTest extends PubPackageResolutionTest {
   test_isEnumConstant() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 enum B {B1, B2, B3}
 ''');
     var B = result.findElement.enum_('B');
diff --git a/pkg/analyzer/test/src/dart/resolution/conditional_expression_test.dart b/pkg/analyzer/test/src/dart/resolution/conditional_expression_test.dart
index 7bf357b3df6..a1302e86ff0 100644
--- a/pkg/analyzer/test/src/dart/resolution/conditional_expression_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/conditional_expression_test.dart
@@ -47,7 +47,7 @@ ConditionalExpression
   }
 
   test_downward_condition() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 void f(int b, int c) {
   a() ? b : c;
 }
@@ -312,7 +312,7 @@ ConditionalExpression
   }
 
   test_upward() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 void f(bool a, int b, int c) {
   var d = a ? b : c;
   print(d);
diff --git a/pkg/analyzer/test/src/dart/resolution/constant_test.dart b/pkg/analyzer/test/src/dart/resolution/constant_test.dart
index 62afe6ca50e..828bbc18615 100644
--- a/pkg/analyzer/test/src/dart/resolution/constant_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/constant_test.dart
@@ -204,8 +204,10 @@ class C {
   static const int f = 42;
 }
 ''');
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 import 'a.dart';
+//     ^^^^^^^^
+// [diag.unusedImport] Unused import: 'a.dart'.
 ''');
 
     var import_ = result.findElement.importFind('package:test/a.dart');
@@ -221,8 +223,10 @@ extension E on int {
   static const int f = 42;
 }
 ''');
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 import 'a.dart';
+//     ^^^^^^^^
+// [diag.unusedImport] Unused import: 'a.dart'.
 ''');
 
     var import_ = result.findElement.importFind('package:test/a.dart');
@@ -240,8 +244,10 @@ mixin M on C {
   static const int f = 42;
 }
 ''');
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 import 'a.dart';
+//     ^^^^^^^^
+// [diag.unusedImport] Unused import: 'a.dart'.
 ''');
 
     var import_ = result.findElement.importFind('package:test/a.dart');
diff --git a/pkg/analyzer/test/src/dart/resolution/constructor_field_initializer_test.dart b/pkg/analyzer/test/src/dart/resolution/constructor_field_initializer_test.dart
index 4f36812b99e..b923b2720d2 100644
--- a/pkg/analyzer/test/src/dart/resolution/constructor_field_initializer_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/constructor_field_initializer_test.dart
@@ -70,7 +70,7 @@ ConstructorFieldInitializer
   }
 
   test_functionExpressionInvocation_blockBody() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   final x;
   A(int a) : x = (() {return a + 1;})();
@@ -129,7 +129,7 @@ ConstructorFieldInitializer
   }
 
   test_functionExpressionInvocation_expressionBody() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   final int x;
   A(int a) : x = (() => a + 1)();
diff --git a/pkg/analyzer/test/src/dart/resolution/field_test.dart b/pkg/analyzer/test/src/dart/resolution/field_test.dart
index d5199f42eca..3a1ae8e6d35 100644
--- a/pkg/analyzer/test/src/dart/resolution/field_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/field_test.dart
@@ -210,7 +210,7 @@ FieldDeclaration
   }
 
   test_session_getterSetter() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   var f = 0;
 }
@@ -223,7 +223,7 @@ class A {
   }
 
   test_type_inferred_int() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   var f = 0;
 }
@@ -232,7 +232,7 @@ class A {
   }
 
   test_type_inferred_Never() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   var f = throw 42;
 }
@@ -241,7 +241,7 @@ class A {
   }
 
   test_type_inferred_noInitializer() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   var f;
 }
@@ -250,7 +250,7 @@ class A {
   }
 
   test_type_inferred_null() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   var f = null;
 }
diff --git a/pkg/analyzer/test/src/dart/resolution/for_statement_test.dart b/pkg/analyzer/test/src/dart/resolution/for_statement_test.dart
index ec8199c2c73..c270f223a26 100644
--- a/pkg/analyzer/test/src/dart/resolution/for_statement_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/for_statement_test.dart
@@ -28,7 +28,7 @@ main() {
 class ForStatementResolutionTest_ForEachPartsWithDeclaration
     extends PubPackageResolutionTest {
   test_async_loopVariable_var_stream() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void f(Stream<int> values) async {
   await for (var v in values) {
     v;
@@ -395,7 +395,7 @@ ForStatement
   }
 
   test_sync_loopVariable_dynamic() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void f(List<int> values) {
   for (dynamic v in values) {
     v;
@@ -478,7 +478,7 @@ ForStatement
   }
 
   test_sync_loopVariable_var_iterable() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void f(Iterable<int> values) {
   for (var v in values) {
     v;
@@ -517,7 +517,7 @@ ForStatement
   }
 
   test_sync_loopVariable_var_list() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void f(List<int> values) {
   for (var v in values) {
     v;
diff --git a/pkg/analyzer/test/src/dart/resolution/function_expression_invocation_test.dart b/pkg/analyzer/test/src/dart/resolution/function_expression_invocation_test.dart
index fad0ae1927e..dbd14cffabd 100644
--- a/pkg/analyzer/test/src/dart/resolution/function_expression_invocation_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/function_expression_invocation_test.dart
@@ -53,7 +53,7 @@ FunctionExpressionInvocation
   }
 
   test_call_infer_fromArguments_listLiteral() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   List<T> call<T>(List<T> _)  {
     throw 42;
@@ -61,6 +61,8 @@ class A {
 }
 
 main(A a) {
+//   ^
+// [diag.mainFirstPositionalParameterType] The type of the first positional parameter of the 'main' function must be a supertype of 'List<String>'.
   a([0]);
 }
 ''');
diff --git a/pkg/analyzer/test/src/dart/resolution/instance_member_inference_class_test.dart b/pkg/analyzer/test/src/dart/resolution/instance_member_inference_class_test.dart
index 311d81bc2f2..956fa5083e6 100644
--- a/pkg/analyzer/test/src/dart/resolution/instance_member_inference_class_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/instance_member_inference_class_test.dart
@@ -7,17 +7,19 @@ import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import 'context_collection_resolution.dart';
+import 'node_text_expectations.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(InstanceMemberInferenceClassTest);
+    defineReflectiveTests(UpdateNodeTextExpectations);
   });
 }
 
 @reflectiveTest
 class InstanceMemberInferenceClassTest extends PubPackageResolutionTest {
   test_field_covariant_fromField() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   covariant num foo = 0;
 }
@@ -31,7 +33,7 @@ class B implements A {
   }
 
   test_field_covariant_fromSetter() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   set foo(covariant num _) {}
 }
@@ -45,13 +47,15 @@ class B implements A {
   }
 
   test_field_fromInitializer_inherited() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   var foo = 0;
 }
 
 class B implements A {
   var foo;
+//    ^^^
+// [diag.notInitializedNonNullableInstanceField] Non-nullable instance field 'foo' must be initialized.
 }
 ''');
     var foo = result.findElement.field('foo', of: 'B');
@@ -59,9 +63,11 @@ class B implements A {
   }
 
   test_field_fromInitializer_preferSuper() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   num foo;
+//    ^^^
+// [diag.notInitializedNonNullableInstanceField] Non-nullable instance field 'foo' must be initialized.
 }
 
 class B implements A {
@@ -73,15 +79,22 @@ class B implements A {
   }
 
   test_field_multiple_fields_incompatible() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   int foo = throw 0;
+//    ^^^
+// [context 1] The member being overridden.
 }
 class B {
   String foo = throw 0;
+//       ^^^
+// [context 2] The member being overridden.
 }
 class C implements A, B {
   var foo;
+//    ^^^
+// [diag.invalidOverride][context 1] 'C.foo' ('dynamic Function()') isn't a valid override of 'A.foo' ('int Function()').
+// [diag.invalidOverride][context 2] 'C.foo' ('dynamic Function()') isn't a valid override of 'B.foo' ('String Function()').
 }
 ''');
     var foo = result.findElement.field('foo', of: 'C');
@@ -89,7 +102,7 @@ class C implements A, B {
   }
 
   test_field_multiple_getters_combined() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   num get foo => throw 0;
 }
@@ -98,6 +111,8 @@ class B {
 }
 class C implements A, B {
   var foo;
+//    ^^^
+// [diag.notInitializedNonNullableInstanceField] Non-nullable instance field 'foo' must be initialized.
 }
 ''');
     var foo = result.findElement.field('foo', of: 'C');
@@ -105,15 +120,22 @@ class C implements A, B {
   }
 
   test_field_multiple_getters_incompatible() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   String get foo => throw 0;
+//           ^^^
+// [context 1] The member being overridden.
 }
 class B {
   int get foo => throw 0;
+//        ^^^
+// [context 2] The member being overridden.
 }
 class C implements A, B {
   var foo;
+//    ^^^
+// [diag.invalidOverride][context 1] 'C.foo' ('dynamic Function()') isn't a valid override of 'A.foo' ('String Function()').
+// [diag.invalidOverride][context 2] 'C.foo' ('dynamic Function()') isn't a valid override of 'B.foo' ('int Function()').
 }
 ''');
     var foo = result.findElement.field('foo', of: 'C');
@@ -121,7 +143,7 @@ class C implements A, B {
   }
 
   test_field_multiple_gettersSetters_final_combined() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   num get foo => throw 0;
 }
@@ -132,7 +154,11 @@ class C {
   set foo(String _) {}
 }
 class X implements A, B, C {
+//    ^
+// [diag.nonAbstractClassInheritsAbstractMemberOne] Missing concrete implementation of 'setter C.foo'.
   final foo;
+//      ^^^
+// [diag.finalNotInitialized] The final variable 'foo' must be initialized.
 }
 ''');
     var foo = result.findElement.field('foo', of: 'X');
@@ -140,18 +166,28 @@ class X implements A, B, C {
   }
 
   test_field_multiple_gettersSetters_final_incompatible() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   String get foo => throw 0;
+//           ^^^
+// [context 1] The member being overridden.
 }
 class B {
   int get foo => throw 0;
+//        ^^^
+// [context 2] The member being overridden.
 }
 class C {
   set foo(String _) {}
 }
 class X implements A, B, C {
+//    ^
+// [diag.nonAbstractClassInheritsAbstractMemberOne] Missing concrete implementation of 'setter C.foo'.
   final foo;
+//      ^^^
+// [diag.invalidOverride][context 1] 'X.foo' ('dynamic Function()') isn't a valid override of 'A.foo' ('String Function()').
+// [diag.invalidOverride][context 2] 'X.foo' ('dynamic Function()') isn't a valid override of 'B.foo' ('int Function()').
+// [diag.finalNotInitialized] The final variable 'foo' must be initialized.
 }
 ''');
     var foo = result.findElement.field('foo', of: 'X');
@@ -159,18 +195,25 @@ class X implements A, B, C {
   }
 
   test_field_multiple_gettersSetters_notFinal_combined_notSame() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   num get foo => throw 0;
+//        ^^^
+// [context 1] The member being overridden.
 }
 class B {
   int get foo => throw 0;
+//        ^^^
+// [context 2] The member being overridden.
 }
 class C {
   set foo(String _) {}
 }
 class X implements A, B, C {
   var foo;
+//    ^^^
+// [diag.invalidOverride][context 1] 'X.foo' ('dynamic Function()') isn't a valid override of 'A.foo' ('num Function()').
+// [diag.invalidOverride][context 2] 'X.foo' ('dynamic Function()') isn't a valid override of 'B.foo' ('int Function()').
 }
 ''');
     var foo = result.findElement.field('foo', of: 'X');
@@ -179,7 +222,7 @@ class X implements A, B, C {
   }
 
   test_field_multiple_gettersSetters_notFinal_combined_same() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   num get foo => throw 0;
 }
@@ -191,6 +234,8 @@ class C {
 }
 class X implements A, B, C {
   var foo;
+//    ^^^
+// [diag.notInitializedNonNullableInstanceField] Non-nullable instance field 'foo' must be initialized.
 }
 ''');
     var foo = result.findElement.field('foo', of: 'X');
@@ -198,18 +243,25 @@ class X implements A, B, C {
   }
 
   test_field_multiple_gettersSetters_notFinal_incompatible_getters() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   String get foo => throw 0;
+//           ^^^
+// [context 1] The member being overridden.
 }
 class B {
   int get foo => throw 0;
+//        ^^^
+// [context 2] The member being overridden.
 }
 class C {
   set foo(int _) {}
 }
 class X implements A, B, C {
   var foo;
+//    ^^^
+// [diag.invalidOverride][context 1] 'X.foo' ('dynamic Function()') isn't a valid override of 'A.foo' ('String Function()').
+// [diag.invalidOverride][context 2] 'X.foo' ('dynamic Function()') isn't a valid override of 'B.foo' ('int Function()').
 }
 ''');
     var foo = result.findElement.field('foo', of: 'X');
@@ -217,9 +269,11 @@ class X implements A, B, C {
   }
 
   test_field_multiple_gettersSetters_notFinal_incompatible_setters() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   int get foo => throw 0;
+//        ^^^
+// [context 1] The member being overridden.
 }
 class B {
   set foo(String _) {}
@@ -229,6 +283,8 @@ class C {
 }
 class X implements A, B, C {
   var foo;
+//    ^^^
+// [diag.invalidOverride][context 1] 'X.foo' ('dynamic Function()') isn't a valid override of 'A.foo' ('int Function()').
 }
 ''');
     var foo = result.findElement.field('foo', of: 'X');
@@ -236,7 +292,7 @@ class X implements A, B, C {
   }
 
   test_field_multiple_setters_combined() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   set foo(num _) {}
 }
@@ -245,6 +301,8 @@ class B {
 }
 class C implements A, B {
   var foo;
+//    ^^^
+// [diag.notInitializedNonNullableInstanceField] Non-nullable instance field 'foo' must be initialized.
 }
 ''');
     var foo = result.findElement.field('foo', of: 'C');
@@ -252,7 +310,7 @@ class C implements A, B {
   }
 
   test_field_multiple_setters_incompatible() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   set foo(String _) {}
 }
@@ -268,7 +326,7 @@ class C implements A, B {
   }
 
   test_getter_multiple_getters_combined() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   num get foo => throw 0;
 }
@@ -284,15 +342,22 @@ class C implements A, B {
   }
 
   test_getter_multiple_getters_incompatible() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   String get foo => throw 0;
+//           ^^^
+// [context 1] The member being overridden.
 }
 class B {
   int get foo => throw 0;
+//        ^^^
+// [context 2] The member being overridden.
 }
 class C implements A, B {
   get foo => throw 0;
+//    ^^^
+// [diag.invalidOverride][context 1] 'C.foo' ('dynamic Function()') isn't a valid override of 'A.foo' ('String Function()').
+// [diag.invalidOverride][context 2] 'C.foo' ('dynamic Function()') isn't a valid override of 'B.foo' ('int Function()').
 }
 ''');
     var foo = result.findElement.getter('foo', of: 'C');
@@ -300,7 +365,7 @@ class C implements A, B {
   }
 
   test_getter_multiple_getters_same() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   int get foo => throw 0;
 }
@@ -316,7 +381,7 @@ class C implements A, B {
   }
 
   test_getter_multiple_gettersSetters_combined() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   num get foo => throw 0;
 }
@@ -327,6 +392,8 @@ class C {
   set foo(String _) {}
 }
 class X implements A, B, C {
+//    ^
+// [diag.nonAbstractClassInheritsAbstractMemberOne] Missing concrete implementation of 'setter C.foo'.
   get foo => throw 0;
 }
 ''');
@@ -335,18 +402,27 @@ class X implements A, B, C {
   }
 
   test_getter_multiple_gettersSetters_incompatible() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   String get foo => throw 0;
+//           ^^^
+// [context 1] The member being overridden.
 }
 class B {
   int get foo => throw 0;
+//        ^^^
+// [context 2] The member being overridden.
 }
 class C {
   set foo(String _) {}
 }
 class X implements A, B, C {
+//    ^
+// [diag.nonAbstractClassInheritsAbstractMemberOne] Missing concrete implementation of 'setter C.foo'.
   get foo => throw 0;
+//    ^^^
+// [diag.invalidOverride][context 1] 'X.foo' ('dynamic Function()') isn't a valid override of 'A.foo' ('String Function()').
+// [diag.invalidOverride][context 2] 'X.foo' ('dynamic Function()') isn't a valid override of 'B.foo' ('int Function()').
 }
 ''');
     var foo = result.findElement.getter('foo', of: 'X');
@@ -354,7 +430,7 @@ class X implements A, B, C {
   }
 
   test_getter_multiple_setters_combined() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   set foo(num _) {}
 }
@@ -362,6 +438,8 @@ class B {
   set foo(int _) {}
 }
 class C implements A, B {
+//    ^
+// [diag.nonAbstractClassInheritsAbstractMemberOne] Missing concrete implementation of 'setter A.foo'.
   get foo => throw 0;
 }
 ''');
@@ -370,7 +448,7 @@ class C implements A, B {
   }
 
   test_getter_multiple_setters_incompatible() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   set foo(String _) {}
 }
@@ -378,6 +456,8 @@ class B {
   set foo(int _) {}
 }
 class C implements A, B {
+//    ^
+// [diag.inconsistentInheritance] Superinterfaces don't have a valid override for 'foo=': A.foo= (void Function(String)), B.foo= (void Function(int)).
   get foo => throw 0;
 }
 ''');
@@ -386,13 +466,17 @@ class C implements A, B {
   }
 
   test_invalid_field_overrides_method() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 abstract class A {
   List<T> foo<T>() {}
+//        ^^^
+// [diag.bodyMightCompleteNormally] The body might complete normally, causing 'null' to be returned, but the return type, 'List<T>', is a potentially non-nullable type.
 }
 
 class B implements A {
   var foo = <String, int>{};
+//    ^^^
+// [diag.conflictingFieldAndMethod] Class 'B' can't define field 'foo' and have method 'A.foo' with the same name.
 }
 ''');
     var foo = result.findElement.field('foo', of: 'B');
@@ -400,23 +484,35 @@ class B implements A {
   }
 
   test_invalid_inheritanceCycle() async {
-    await resolveTestCode('''
+    await resolveTestCodeWithDiagnostics('''
 class A extends C {}
+//    ^
+// [diag.recursiveInterfaceInheritance] 'A' can't be a superinterface of itself: B, C, A.
 class B extends A {}
+//    ^
+// [diag.recursiveInterfaceInheritance] 'B' can't be a superinterface of itself: B, C, A.
 class C extends B {}
+//    ^
+// [diag.recursiveInterfaceInheritance] 'C' can't be a superinterface of itself: B, C, A.
 ''');
   }
 
   test_method_parameter_covariant_named() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo({num p}) {}
+//              ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 class B {
   void foo({covariant num p}) {}
+//                        ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 class C implements A, B {
   void foo({int p}) {}
+//              ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 ''');
     var p = result.findElement.method('foo', of: 'C').formalParameters[0];
@@ -424,15 +520,21 @@ class C implements A, B {
   }
 
   test_method_parameter_covariant_positional() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo([num p]) {}
+//              ^
+// [diag.missingDefaultValueForParameterPositional] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 class B {
   void foo([covariant num p]) {}
+//                        ^
+// [diag.missingDefaultValueForParameterPositional] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 class C implements A, B {
   void foo([int p]) {}
+//              ^
+// [diag.missingDefaultValueForParameterPositional] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 ''');
     var p = result.findElement.method('foo', of: 'C').formalParameters[0];
@@ -440,7 +542,7 @@ class C implements A, B {
   }
 
   test_method_parameter_covariant_required() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo(num p) {}
 }
@@ -456,15 +558,21 @@ class C implements A, B {
   }
 
   test_method_parameter_named_multiple_combined() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo({int p}) {}
+//              ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 class B {
   void foo({num p}) {}
+//              ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 class C implements A, B {
   void foo({p}) {}
+//          ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 ''');
     var p = result.findElement.method('foo', of: 'C').formalParameters[0];
@@ -472,15 +580,21 @@ class C implements A, B {
   }
 
   test_method_parameter_named_multiple_incompatible() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo({int p}) {}
+//              ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 class B {
   void foo({int q}) {}
+//              ^
+// [diag.missingDefaultValueForParameter] The parameter 'q' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 class C implements A, B {
   void foo({p}) {}
+//     ^^^
+// [diag.noCombinedSuperSignature] Can't infer missing types in 'C' from overridden methods: A.foo (void Function({int p})), B.foo (void Function({int q})).
 }
 ''');
     var p = result.findElement.method('foo', of: 'C').formalParameters[0];
@@ -488,15 +602,21 @@ class C implements A, B {
   }
 
   test_method_parameter_named_multiple_same() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo({int p}) {}
+//              ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 class B {
   void foo({int p}) {}
+//              ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 class C implements A, B {
   void foo({p}) {}
+//          ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 ''');
     var p = result.findElement.method('foo', of: 'C').formalParameters[0];
@@ -504,15 +624,19 @@ class C implements A, B {
   }
 
   test_method_parameter_namedAndRequired() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo({int p}) {}
+//              ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 class B {
   void foo(int p) {}
 }
 class C implements A, B {
   void foo(p) {}
+//     ^^^
+// [diag.noCombinedSuperSignature] Can't infer missing types in 'C' from overridden methods: A.foo (void Function({int p})), B.foo (void Function(int)).
 }
 ''');
     var p = result.findElement.method('foo', of: 'C').formalParameters[0];
@@ -520,7 +644,7 @@ class C implements A, B {
   }
 
   test_method_parameter_required_multiple_combined() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo(int p) {}
 }
@@ -536,7 +660,7 @@ class C implements A, B {
   }
 
   test_method_parameter_required_multiple_different_merge() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo(Object? p) {}
 }
@@ -554,7 +678,7 @@ class C implements A, B {
   }
 
   test_method_parameter_required_multiple_incompatible() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo(int p) {}
 }
@@ -563,6 +687,8 @@ class B {
 }
 class C implements A, B {
   void foo(p) {}
+//     ^^^
+// [diag.noCombinedSuperSignature] Can't infer missing types in 'C' from overridden methods: A.foo (void Function(int)), B.foo (void Function(double)).
 }
 ''');
     var p = result.findElement.method('foo', of: 'C').formalParameters[0];
@@ -570,7 +696,7 @@ class C implements A, B {
   }
 
   test_method_parameter_required_multiple_same() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo(int p) {}
 }
@@ -586,7 +712,7 @@ class C implements A, B {
   }
 
   test_method_parameter_required_single_generic() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A<E> {
   void foo(E p) {}
 }
@@ -599,15 +725,21 @@ class C<T> implements A<T> {
   }
 
   test_method_parameter_requiredAndPositional() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo(int p) {}
 }
 class B {
   void foo([int p]) {}
+//     ^^^
+// [context 1] The member being overridden.
+//              ^
+// [diag.missingDefaultValueForParameterPositional] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 class C implements A, B {
   void foo(p) {}
+//     ^^^
+// [diag.invalidOverride][context 1] 'C.foo' ('void Function(int)') isn't a valid override of 'B.foo' ('void Function([int])').
 }
 ''');
     var p = result.findElement.method('foo', of: 'C').formalParameters[0];
@@ -615,7 +747,7 @@ class C implements A, B {
   }
 
   test_method_return_multiple_different_combined() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   int foo() => 0;
 }
@@ -631,7 +763,7 @@ class C implements A, B {
   }
 
   test_method_return_multiple_different_dynamic() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   int foo() => 0;
 }
@@ -647,7 +779,7 @@ class C implements A, B {
   }
 
   test_method_return_multiple_different_generic() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A<E> {
   E foo() => throw 0;
 }
@@ -656,6 +788,8 @@ class B<E> {
 }
 class C implements A<int>, B<double> {
   foo() => throw 0;
+//^^^
+// [diag.noCombinedSuperSignature] Can't infer missing types in 'C' from overridden methods: A.foo (int Function()), B.foo (double Function()).
 }
 ''');
     var foo = result.findElement.method('foo', of: 'C');
@@ -663,7 +797,7 @@ class C implements A<int>, B<double> {
   }
 
   test_method_return_multiple_different_incompatible() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   int foo() => 0;
 }
@@ -672,6 +806,8 @@ class B {
 }
 class C implements A, B {
   foo() => 0;
+//^^^
+// [diag.noCombinedSuperSignature] Can't infer missing types in 'C' from overridden methods: A.foo (int Function()), B.foo (double Function()).
 }
 ''');
     var foo = result.findElement.method('foo', of: 'C');
@@ -679,7 +815,7 @@ class C implements A, B {
   }
 
   test_method_return_multiple_different_merge() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   Object? foo() => throw 0;
 }
@@ -697,7 +833,7 @@ class C implements A, B {
   }
 
   test_method_return_multiple_different_void() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   int foo() => 0;
 }
@@ -713,15 +849,21 @@ class C implements A, B {
   }
 
   test_method_return_multiple_same_generic() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A<E> {
   E foo() => 0;
+//           ^
+// [diag.returnOfInvalidTypeFromMethod] A value of type 'int' can't be returned from the method 'foo' because it has a return type of 'E'.
 }
 class B<E> {
   E foo() => 0;
+//           ^
+// [diag.returnOfInvalidTypeFromMethod] A value of type 'int' can't be returned from the method 'foo' because it has a return type of 'E'.
 }
 class C<T> implements A<T>, B<T> {
   foo() => 0;
+//         ^
+// [diag.returnOfInvalidTypeFromMethod] A value of type 'int' can't be returned from the method 'foo' because it has a return type of 'T'.
 }
 ''');
     var foo = result.findElement.method('foo', of: 'C');
@@ -729,7 +871,7 @@ class C<T> implements A<T>, B<T> {
   }
 
   test_method_return_multiple_same_nonVoid() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   int foo() => 0;
 }
@@ -745,15 +887,21 @@ class C implements A, B {
   }
 
   test_method_return_multiple_same_void() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo() {};
+//             ^
+// [diag.expectedClassMember] Expected a class member.
 }
 class B {
   void foo() {};
+//             ^
+// [diag.expectedClassMember] Expected a class member.
 }
 class C implements A, B {
   foo() {};
+//        ^
+// [diag.expectedClassMember] Expected a class member.
 }
 ''');
     var foo = result.findElement.method('foo', of: 'C');
@@ -761,7 +909,7 @@ class C implements A, B {
   }
 
   test_method_return_single() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   int foo() => 0;
 }
@@ -774,7 +922,7 @@ class B extends A {
   }
 
   test_method_return_single_generic() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A<E> {
   E foo() => throw 0;
 }
@@ -787,7 +935,7 @@ class B<T> extends A<T> {
   }
 
   test_setter_covariant_fromSetter() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   set foo(num _) {}
 }
@@ -803,7 +951,7 @@ class C implements A, B {
   }
 
   test_setter_multiple_getters_combined() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   num get foo => throw 0;
 }
@@ -811,6 +959,8 @@ class B {
   int get foo => throw 0;
 }
 class C implements A, B {
+//    ^
+// [diag.nonAbstractClassInheritsAbstractMemberOne] Missing concrete implementation of 'getter B.foo'.
   set foo(x) {}
 }
 ''');
@@ -819,7 +969,7 @@ class C implements A, B {
   }
 
   test_setter_multiple_getters_incompatible() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   String get foo => throw 0;
 }
@@ -827,6 +977,8 @@ class B {
   int get foo => throw 0;
 }
 class C implements A, B {
+//    ^
+// [diag.inconsistentInheritance] Superinterfaces don't have a valid override for 'foo': A.foo (String Function()), B.foo (int Function()).
   set foo(x) {}
 }
 ''');
@@ -835,7 +987,7 @@ class C implements A, B {
   }
 
   test_setter_multiple_gettersSetters_combined() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   set foo(num _) {}
 }
@@ -846,6 +998,8 @@ class C {
   String get foo => throw 0;
 }
 class X implements A, B, C {
+//    ^
+// [diag.nonAbstractClassInheritsAbstractMemberOne] Missing concrete implementation of 'getter C.foo'.
   set foo(x) {}
 }
 ''');
@@ -854,7 +1008,7 @@ class X implements A, B, C {
   }
 
   test_setter_multiple_gettersSetters_incompatible() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   set foo(String _) {}
 }
@@ -865,6 +1019,8 @@ class C {
   int get foo => throw 0;
 }
 class X implements A, B, C {
+//    ^
+// [diag.nonAbstractClassInheritsAbstractMemberOne] Missing concrete implementation of 'getter C.foo'.
   set foo(x) {}
 }
 ''');
@@ -873,7 +1029,7 @@ class X implements A, B, C {
   }
 
   test_setter_multiple_setters_combined() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   set foo(num _) {}
 }
@@ -889,7 +1045,7 @@ class C implements A, B {
   }
 
   test_setter_multiple_setters_incompatible() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   set foo(String _) {}
 }
@@ -905,9 +1061,11 @@ class C implements A, B {
   }
 
   test_setter_single_setter_withoutParameter() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   set foo() {}
+//    ^^^
+// [diag.wrongNumberOfParametersForSetter] Setters must declare exactly one required positional parameter.
 }
 class B implements A {
   set foo(x) {}
diff --git a/pkg/analyzer/test/src/dart/resolution/instance_member_inference_mixin_test.dart b/pkg/analyzer/test/src/dart/resolution/instance_member_inference_mixin_test.dart
index 3dece300642..d30f9cf75d4 100644
--- a/pkg/analyzer/test/src/dart/resolution/instance_member_inference_mixin_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/instance_member_inference_mixin_test.dart
@@ -5,33 +5,47 @@
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import 'context_collection_resolution.dart';
+import 'node_text_expectations.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(InstanceMemberInferenceClassTest);
+    defineReflectiveTests(UpdateNodeTextExpectations);
   });
 }
 
 @reflectiveTest
 class InstanceMemberInferenceClassTest extends PubPackageResolutionTest {
   test_invalid_inheritanceCycle() async {
-    await resolveTestCode('''
+    await resolveTestCodeWithDiagnostics('''
 class A extends C {}
+//    ^
+// [diag.recursiveInterfaceInheritance] 'A' can't be a superinterface of itself: B, C, A.
 class B extends A {}
+//    ^
+// [diag.recursiveInterfaceInheritance] 'B' can't be a superinterface of itself: B, C, A.
 class C extends B {}
+//    ^
+// [diag.recursiveInterfaceInheritance] 'C' can't be a superinterface of itself: B, C, A.
 ''');
   }
 
   test_method_parameter_named_multiple_combined() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo({int p}) {}
+//              ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 class B {
   void foo({num p}) {}
+//              ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 mixin M on A, B {
   void foo({p}) {}
+//          ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 ''');
     var p = result.findElement.method('foo', of: 'M').formalParameters[0];
@@ -39,15 +53,23 @@ mixin M on A, B {
   }
 
   test_method_parameter_named_multiple_incompatible() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo({int p}) {}
+//              ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 class B {
   void foo({int q}) {}
+//              ^
+// [diag.missingDefaultValueForParameter] The parameter 'q' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 mixin M on A, B {
+//    ^
+// [diag.inconsistentInheritance] Superinterfaces don't have a valid override for 'foo': A.foo (void Function({int p})), B.foo (void Function({int q})).
   void foo({p}) {}
+//     ^^^
+// [diag.noCombinedSuperSignature] Can't infer missing types in 'M' from overridden methods: A.foo (void Function({int p})), B.foo (void Function({int q})).
 }
 ''');
     var p = result.findElement.method('foo', of: 'M').formalParameters[0];
@@ -55,15 +77,21 @@ mixin M on A, B {
   }
 
   test_method_parameter_named_multiple_same() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo({int p}) {}
+//              ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 class B {
   void foo({int p}) {}
+//              ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 mixin M on A, B {
   void foo({p}) {}
+//          ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 ''');
     var p = result.findElement.method('foo', of: 'M').formalParameters[0];
@@ -71,15 +99,21 @@ mixin M on A, B {
   }
 
   test_method_parameter_namedAndRequired() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo({int p}) {}
+//              ^
+// [diag.missingDefaultValueForParameter] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 class B {
   void foo(int p) {}
 }
 mixin M on A, B {
+//    ^
+// [diag.inconsistentInheritance] Superinterfaces don't have a valid override for 'foo': A.foo (void Function({int p})), B.foo (void Function(int)).
   void foo(p) {}
+//     ^^^
+// [diag.noCombinedSuperSignature] Can't infer missing types in 'M' from overridden methods: A.foo (void Function({int p})), B.foo (void Function(int)).
 }
 ''');
     var p = result.findElement.method('foo', of: 'M').formalParameters[0];
@@ -87,7 +121,7 @@ mixin M on A, B {
   }
 
   test_method_parameter_required_multiple_combined() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo(int p) {}
 }
@@ -103,7 +137,7 @@ mixin M on A, B {
   }
 
   test_method_parameter_required_multiple_different_merge() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo(Object? p) {}
 }
@@ -121,7 +155,7 @@ mixin M on A, B {
   }
 
   test_method_parameter_required_multiple_incompatible() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo(int p) {}
 }
@@ -129,7 +163,11 @@ class B {
   void foo(double p) {}
 }
 mixin M on A, B {
+//    ^
+// [diag.inconsistentInheritance] Superinterfaces don't have a valid override for 'foo': A.foo (void Function(int)), B.foo (void Function(double)).
   void foo(p) {}
+//     ^^^
+// [diag.noCombinedSuperSignature] Can't infer missing types in 'M' from overridden methods: A.foo (void Function(int)), B.foo (void Function(double)).
 }
 ''');
     var p = result.findElement.method('foo', of: 'M').formalParameters[0];
@@ -137,7 +175,7 @@ mixin M on A, B {
   }
 
   test_method_parameter_required_multiple_same() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo(int p) {}
 }
@@ -153,7 +191,7 @@ mixin M on A, B {
   }
 
   test_method_parameter_required_single_generic() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A<E> {
   void foo(E p) {}
 }
@@ -166,15 +204,21 @@ mixin M<T> on A<T> {
   }
 
   test_method_parameter_requiredAndPositional() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo(int p) {}
 }
 class B {
   void foo([int p]) {}
+//     ^^^
+// [context 1] The member being overridden.
+//              ^
+// [diag.missingDefaultValueForParameterPositional] The parameter 'p' can't have a value of 'null' because of its type, but the implicit default value is 'null'.
 }
 mixin M on A, B {
   void foo(p) {}
+//     ^^^
+// [diag.invalidOverride][context 1] 'M.foo' ('void Function(int)') isn't a valid override of 'B.foo' ('void Function([int])').
 }
 ''');
     var p = result.findElement.method('foo', of: 'M').formalParameters[0];
@@ -182,7 +226,7 @@ mixin M on A, B {
   }
 
   test_method_return_multiple_different_combined() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   int foo() => 0;
 }
@@ -198,7 +242,7 @@ mixin M on A, B {
   }
 
   test_method_return_multiple_different_dynamic() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   int foo() => 0;
 }
@@ -214,7 +258,7 @@ mixin M on A, B {
   }
 
   test_method_return_multiple_different_generic() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A<E> {
   E foo() => throw 0;
 }
@@ -222,7 +266,11 @@ class B<E> {
   E foo() => throw 0;
 }
 mixin M on A<int>, B<double> {
+//    ^
+// [diag.inconsistentInheritance] Superinterfaces don't have a valid override for 'foo': A.foo (int Function()), B.foo (double Function()).
   foo() => throw 0;
+//^^^
+// [diag.noCombinedSuperSignature] Can't infer missing types in 'M' from overridden methods: A.foo (int Function()), B.foo (double Function()).
 }
 ''');
     var foo = result.findElement.method('foo', of: 'M');
@@ -230,7 +278,7 @@ mixin M on A<int>, B<double> {
   }
 
   test_method_return_multiple_different_incompatible() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   int foo() => 0;
 }
@@ -238,7 +286,11 @@ class B {
   double foo() => 0.0;
 }
 mixin M on A, B {
+//    ^
+// [diag.inconsistentInheritance] Superinterfaces don't have a valid override for 'foo': A.foo (int Function()), B.foo (double Function()).
   foo() => 0;
+//^^^
+// [diag.noCombinedSuperSignature] Can't infer missing types in 'M' from overridden methods: A.foo (int Function()), B.foo (double Function()).
 }
 ''');
     var foo = result.findElement.method('foo', of: 'M');
@@ -246,7 +298,7 @@ mixin M on A, B {
   }
 
   test_method_return_multiple_different_merge() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   Object? foo() => throw 0;
 }
@@ -264,7 +316,7 @@ mixin M on A, B {
   }
 
   test_method_return_multiple_different_void() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   int foo() => 0;
 }
@@ -280,15 +332,21 @@ mixin M on A, B {
   }
 
   test_method_return_multiple_same_generic() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A<E> {
   E foo() => 0;
+//           ^
+// [diag.returnOfInvalidTypeFromMethod] A value of type 'int' can't be returned from the method 'foo' because it has a return type of 'E'.
 }
 class B<E> {
   E foo() => 0;
+//           ^
+// [diag.returnOfInvalidTypeFromMethod] A value of type 'int' can't be returned from the method 'foo' because it has a return type of 'E'.
 }
 mixin M<T> on A<T>, B<T> {
   foo() => 0;
+//         ^
+// [diag.returnOfInvalidTypeFromMethod] A value of type 'int' can't be returned from the method 'foo' because it has a return type of 'T'.
 }
 ''');
     var foo = result.findElement.method('foo', of: 'M');
@@ -296,7 +354,7 @@ mixin M<T> on A<T>, B<T> {
   }
 
   test_method_return_multiple_same_nonVoid() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   int foo() => 0;
 }
@@ -312,15 +370,21 @@ mixin M on A, B {
   }
 
   test_method_return_multiple_same_void() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   void foo() {};
+//             ^
+// [diag.expectedClassMember] Expected a class member.
 }
 class B {
   void foo() {};
+//             ^
+// [diag.expectedClassMember] Expected a class member.
 }
 mixin M on A, B {
   foo() {};
+//        ^
+// [diag.expectedClassMember] Expected a class member.
 }
 ''');
     var foo = result.findElement.method('foo', of: 'M');
@@ -328,7 +392,7 @@ mixin M on A, B {
   }
 
   test_method_return_single() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A {
   int foo() => 0;
 }
@@ -341,7 +405,7 @@ class B extends A {
   }
 
   test_method_return_single_generic() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 class A<E> {
   E foo() => throw 0;
 }
diff --git a/pkg/analyzer/test/src/dart/resolution/library_element_test.dart b/pkg/analyzer/test/src/dart/resolution/library_element_test.dart
index c56f7a9c14d..056c874a08c 100644
--- a/pkg/analyzer/test/src/dart/resolution/library_element_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/library_element_test.dart
@@ -22,10 +22,15 @@ main() {
 
 @reflectiveTest
 class LibraryElementTest_featureSet extends PubPackageResolutionTest {
+  static String get _currentLanguageVersion {
+    var currentVersion = ExperimentStatus.currentVersion;
+    return '${currentVersion.major}.${currentVersion.minor}';
+  }
+
   test_language205() async {
     writeTestPackageConfig(PackageConfigFileBuilder(), languageVersion: '2.5');
 
-    var result = await resolveTestCode('');
+    var result = await resolveTestCodeWithDiagnostics('');
 
     _assertLanguageVersion(
       result,
@@ -44,7 +49,7 @@ class LibraryElementTest_featureSet extends PubPackageResolutionTest {
   test_language208() async {
     writeTestPackageConfig(PackageConfigFileBuilder(), languageVersion: '2.8');
 
-    var result = await resolveTestCode('');
+    var result = await resolveTestCodeWithDiagnostics('');
 
     _assertLanguageVersion(
       result,
@@ -64,7 +69,10 @@ class LibraryElementTest_featureSet extends PubPackageResolutionTest {
   test_language208_override205() async {
     writeTestPackageConfig(PackageConfigFileBuilder(), languageVersion: '2.8');
 
-    var result = await resolveTestCode('// @dart = 2.5');
+    var result = await resolveTestCodeWithDiagnostics(r'''
+// @dart = 2.5
+// [diag.illegalLanguageVersionOverride][column 1][length 14] The language version must be >=2.12.0.
+''');
 
     // Valid override, less than the latest supported language version.
     _assertLanguageVersion(
@@ -84,7 +92,7 @@ class LibraryElementTest_featureSet extends PubPackageResolutionTest {
   test_language209() async {
     writeTestPackageConfig(PackageConfigFileBuilder(), languageVersion: '2.9');
 
-    var result = await resolveTestCode('');
+    var result = await resolveTestCodeWithDiagnostics('');
 
     _assertLanguageVersion(
       result,
@@ -104,7 +112,10 @@ class LibraryElementTest_featureSet extends PubPackageResolutionTest {
   test_language212_override399() async {
     writeTestPackageConfig(PackageConfigFileBuilder(), languageVersion: '2.12');
 
-    var result = await resolveTestCode('// @dart = 3.99');
+    var result = await resolveTestCodeWithDiagnostics('''
+// @dart = 3.99
+// [diag.invalidLanguageVersionOverrideGreater][column 1][length 15] The language version override can't specify a version greater than the latest known language version: $_currentLanguageVersion.
+''');
 
     // Invalid override: minor is greater than the latest minor.
     _assertLanguageVersion(
@@ -126,7 +137,10 @@ class LibraryElementTest_featureSet extends PubPackageResolutionTest {
   test_language212_override400() async {
     writeTestPackageConfig(PackageConfigFileBuilder(), languageVersion: '2.12');
 
-    var result = await resolveTestCode('// @dart = 4.00');
+    var result = await resolveTestCodeWithDiagnostics('''
+// @dart = 4.00
+// [diag.invalidLanguageVersionOverrideGreater][column 1][length 15] The language version override can't specify a version greater than the latest known language version: $_currentLanguageVersion.
+''');
 
     // Invalid override: major is greater than the latest major.
     _assertLanguageVersion(
diff --git a/pkg/analyzer/test/src/dart/resolution/library_export_test.dart b/pkg/analyzer/test/src/dart/resolution/library_export_test.dart
index 68440f0462f..6304f87fa82 100644
--- a/pkg/analyzer/test/src/dart/resolution/library_export_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/library_export_test.dart
@@ -375,7 +375,7 @@ ExportDirective
 get f => null;
 set f(_) {}
 ''');
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 export 'a.dart';
 ''');
     var exportNamespace = result.libraryElement.exportNamespace;
diff --git a/pkg/analyzer/test/src/dart/resolution/logical_or_pattern_test.dart b/pkg/analyzer/test/src/dart/resolution/logical_or_pattern_test.dart
index 78670500313..d9f075ed5e9 100644
--- a/pkg/analyzer/test/src/dart/resolution/logical_or_pattern_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/logical_or_pattern_test.dart
@@ -77,9 +77,21 @@ LogicalOrPattern
 
   test_switchCase_topLevel3() async {
     // https://github.com/dart-lang/sdk/issues/60168
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 var _ = switch (0) {
+//  ^
+// [diag.unusedElement] The declaration '_' isn't referenced.
   var a || var a || var a => 0,
+//    ^
+// [diag.unusedLocalVariable] The value of the local variable 'a' isn't used.
+//      ^^^^^^^^
+// [diag.deadCode] Dead code.
+//             ^
+// [diag.unusedLocalVariable] The value of the local variable 'a' isn't used.
+//               ^^^^^^^^
+// [diag.deadCode] Dead code.
+//                      ^
+// [diag.unusedLocalVariable] The value of the local variable 'a' isn't used.
 };
 ''');
 
diff --git a/pkg/analyzer/test/src/dart/resolution/metadata_test.dart b/pkg/analyzer/test/src/dart/resolution/metadata_test.dart
index a160682271b..c2455a5c11f 100644
--- a/pkg/analyzer/test/src/dart/resolution/metadata_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/metadata_test.dart
@@ -206,13 +206,17 @@ void f(List<int> list) {
   }
 
   test_location_forEachPartsWithDeclaration() async {
-    await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
+const foo = 42;
 void f() {
-  for (var @foo x = 0;;) {}
+  for (@foo var x = 0;;) {
+    x;
+    break;
+  }
 }
 ''');
-    // This is invalid code.
-    // No checks, as long as it does not crash.
+
+    _assertAtFoo42(result);
   }
 
   test_location_libraryDirective() async {
@@ -295,13 +299,16 @@ A
   }
 
   test_location_localVariableDeclaration() async {
-    await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
+const foo = 42;
 void f() {
-  var @foo x;
+  @foo
+  var x;
+  x;
 }
 ''');
-    // This is invalid code.
-    // No checks, as long as it does not crash.
+
+    _assertAtFoo42(result);
   }
 
   test_location_methodDeclaration() async {
@@ -552,14 +559,18 @@ A
   }
 
   test_value_class_namedConstructor_unresolved_hasFormalParameter() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   const A();
 }
 
 void f(int named) {
   @A.named(42)
+//^^^^^^^^^^^^
+// [diag.invalidAnnotation] Annotation must be either a const variable reference or const constructor invocation.
   int x = 0;
+//    ^
+// [diag.unusedLocalVariable] The value of the local variable 'x' isn't used.
 }
 ''');
 
@@ -1007,12 +1018,15 @@ A<int>
   }
 
   test_value_genericClass_instanceGetter() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A<T> {
   T get foo {}
+//      ^^^
+// [diag.bodyMightCompleteNormally] The body might complete normally, causing 'null' to be returned, but the return type, 'T', is a potentially non-nullable type.
 }
 
 @A.foo
+// [diag.invalidAnnotation][column 1][length 6] Annotation must be either a const variable reference or const constructor invocation.
 void f() {}
 ''');
 
@@ -1094,12 +1108,15 @@ A<dynamic>
   }
 
   test_value_genericClass_staticGetter() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A<T> {
   static T get foo {}
+//       ^
+// [diag.typeParameterReferencedByStatic] Static members can't reference type parameters of the class.
 }
 
 @A.foo
+// [diag.invalidAnnotation][column 1][length 6] Annotation must be either a const variable reference or const constructor invocation.
 void f() {}
 ''');
 
diff --git a/pkg/analyzer/test/src/dart/resolution/super_constructor_invocation_test.dart b/pkg/analyzer/test/src/dart/resolution/super_constructor_invocation_test.dart
index 9f48fbad872..8d4351885f8 100644
--- a/pkg/analyzer/test/src/dart/resolution/super_constructor_invocation_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/super_constructor_invocation_test.dart
@@ -84,13 +84,15 @@ SuperConstructorInvocation
   }
 
   test_named_unresolved_hasFormalParameter() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {
   A(int a);
 }
 
 class B extends A {
   B(int named) : super.named(0);
+//               ^^^^^^^^^^^^^^
+// [diag.undefinedConstructorInInitializer] The class 'A' doesn't have a constructor named 'named'.
 }
 ''');
 
diff --git a/pkg/analyzer/test/src/dart/resolution/top_level_variable_test.dart b/pkg/analyzer/test/src/dart/resolution/top_level_variable_test.dart
index 094405d55e8..46d0e89b4cb 100644
--- a/pkg/analyzer/test/src/dart/resolution/top_level_variable_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/top_level_variable_test.dart
@@ -154,7 +154,7 @@ VariableDeclaration
   }
 
   test_session_getterSetter() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v = 0;
 ''');
     var getter = result.findElement.topGet('v');
@@ -165,28 +165,28 @@ var v = 0;
   }
 
   test_type_inferred_int() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v = 0;
 ''');
     assertType(result.findElement.topVar('v').type, 'int');
   }
 
   test_type_inferred_Never() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v = throw 42;
 ''');
     assertType(result.findElement.topVar('v').type, 'Never');
   }
 
   test_type_inferred_noInitializer() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v;
 ''');
     assertType(result.findElement.topVar('v').type, 'dynamic');
   }
 
   test_type_inferred_null() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v = null;
 ''');
     assertType(result.findElement.topVar('v').type, 'dynamic');
diff --git a/pkg/analyzer/test/src/dart/resolution/type_inference/equality_expressions_test.dart b/pkg/analyzer/test/src/dart/resolution/type_inference/equality_expressions_test.dart
index f3d45da69cb..87fde8f07d9 100644
--- a/pkg/analyzer/test/src/dart/resolution/type_inference/equality_expressions_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/type_inference/equality_expressions_test.dart
@@ -18,7 +18,7 @@ main() {
 @reflectiveTest
 class EqualTest extends PubPackageResolutionTest {
   test_simple() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 void f(Object a, Object b) {
   var c = a == b;
   print(c);
@@ -31,7 +31,7 @@ void f(Object a, Object b) {
 @reflectiveTest
 class NotEqualTest extends PubPackageResolutionTest {
   test_simple() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 void f(Object a, Object b) {
   var c = a != b;
   print(c);
diff --git a/pkg/analyzer/test/src/dart/resolution/type_inference/function_expression_test.dart b/pkg/analyzer/test/src/dart/resolution/type_inference/function_expression_test.dart
index 85674f83850..3e0cb3df73a 100644
--- a/pkg/analyzer/test/src/dart/resolution/type_inference/function_expression_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/type_inference/function_expression_test.dart
@@ -494,7 +494,7 @@ FunctionExpression
   }
 
   test_downward_argumentType_Null() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void foo(void Function(Null) a) {}
 
 main() {
@@ -632,7 +632,7 @@ FunctionExpression
   }
 
   test_noContext_returnType_async_blockBody() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v = () async {
   return 0;
 };
@@ -641,14 +641,14 @@ var v = () async {
   }
 
   test_noContext_returnType_async_expressionBody() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v = () async => 0;
 ''');
     _assertReturnType(result, '() async =>', 'Future<int>');
   }
 
   test_noContext_returnType_asyncStar_blockBody() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v = () async* {
   yield 0;
 };
@@ -657,7 +657,7 @@ var v = () async* {
   }
 
   test_noContext_returnType_asyncStar_blockBody_hasReturn_empty() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 var v = () async* {
   yield 0;
   return;
@@ -667,7 +667,7 @@ var v = () async* {
   }
 
   test_noContext_returnType_asyncStar_blockBody_hasReturn_noYield() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 var v = () async* {
   return;
 };
@@ -676,7 +676,7 @@ var v = () async* {
   }
 
   test_noContext_returnType_asyncStar_blockBody_lubNum() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 var v = () async* {
   yield 0;
   yield 1.1;
@@ -686,7 +686,7 @@ var v = () async* {
   }
 
   test_noContext_returnType_asyncStar_blockBody_lubObject() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 var v = () async* {
   yield 0;
   yield '';
@@ -696,7 +696,7 @@ var v = () async* {
   }
 
   test_noContext_returnType_asyncStar_blockBody_lubWithNull() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 var v = () async* {
   yield 0;
   yield null;
@@ -706,7 +706,7 @@ var v = () async* {
   }
 
   test_noContext_returnType_sync_blockBody() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v = () {
   return 0;
 };
@@ -715,7 +715,7 @@ var v = () {
   }
 
   test_noContext_returnType_sync_blockBody_dynamic() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v = (dynamic a) {
   return a;
 };
@@ -724,7 +724,7 @@ var v = (dynamic a) {
   }
 
   test_noContext_returnType_sync_blockBody_Never() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v = () {
   throw 42;
 };
@@ -733,7 +733,7 @@ var v = () {
   }
 
   test_noContext_returnType_sync_blockBody_notNullable() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v = (bool b) {
   if (b) return 0;
   return 1.2;
@@ -826,7 +826,7 @@ main() {
   }
 
   test_noContext_returnType_sync_blockBody_null_hasReturn() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v = (bool b) {
   if (b) return;
 };
@@ -835,14 +835,14 @@ var v = (bool b) {
   }
 
   test_noContext_returnType_sync_blockBody_null_noReturn() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v = () {};
 ''');
     _assertReturnType(result, '() {}', 'Null');
   }
 
   test_noContext_returnType_sync_blockBody_nullable() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v = (bool b) {
   if (b) return 0;
 };
@@ -880,28 +880,28 @@ main() {
   }
 
   test_noContext_returnType_sync_expressionBody_dynamic() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v = (dynamic a) => a;
 ''');
     _assertReturnType(result, '(dynamic a) =>', 'dynamic');
   }
 
   test_noContext_returnType_sync_expressionBody_Never() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v = () => throw 42;
 ''');
     _assertReturnType(result, '() =>', 'Never');
   }
 
   test_noContext_returnType_sync_expressionBody_notNullable() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v = () => 42;
 ''');
     _assertReturnType(result, '() =>', 'int');
   }
 
   test_noContext_returnType_sync_expressionBody_Null() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 main() {
   var v = () => null;
   v;
@@ -911,7 +911,7 @@ main() {
   }
 
   test_noContext_returnType_syncStar_blockBody() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 var v = () sync* {
   yield 0;
 };
@@ -920,7 +920,7 @@ var v = () sync* {
   }
 
   test_noContext_returnType_syncStar_blockBody_hasReturn_empty() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 var v = () sync* {
   yield 0;
   return;
@@ -930,7 +930,7 @@ var v = () sync* {
   }
 
   test_noContext_returnType_syncStar_blockBody_hasReturn_noYield() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 var v = () sync* {
   return;
 };
@@ -939,7 +939,7 @@ var v = () sync* {
   }
 
   test_noContext_returnType_syncStar_blockBody_lubNum() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 var v = () sync* {
   yield 0;
   yield 1.1;
@@ -949,7 +949,7 @@ var v = () sync* {
   }
 
   test_noContext_returnType_syncStar_blockBody_lubObject() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 var v = () sync* {
   yield 0;
   yield '';
@@ -959,7 +959,7 @@ var v = () sync* {
   }
 
   test_noContext_returnType_syncStar_blockBody_lubWithNull() async {
-    var result = await resolveTestCode(r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 var v = () sync* {
   yield 0;
   yield null;
diff --git a/pkg/analyzer/test/src/dart/resolution/type_inference/map_literal_test.dart b/pkg/analyzer/test/src/dart/resolution/type_inference/map_literal_test.dart
index c39f1cfcf50..2914100f315 100644
--- a/pkg/analyzer/test/src/dart/resolution/type_inference/map_literal_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/type_inference/map_literal_test.dart
@@ -42,7 +42,7 @@ Map<int, int> a = {1 : 2};
   }
 
   test_context_noTypeArgs_noElements_futureOr() async {
-    var result = await resolveTestCode('''
+    var result = await resolveTestCodeWithDiagnostics('''
 import 'dart:async';
 
 FutureOr<Map<int, String>> f() {
diff --git a/pkg/analyzer/test/src/task/strong/dart2_inference_test.dart b/pkg/analyzer/test/src/task/strong/dart2_inference_test.dart
index 58cf7482de6..ecdad7ca0fd 100644
--- a/pkg/analyzer/test/src/task/strong/dart2_inference_test.dart
+++ b/pkg/analyzer/test/src/task/strong/dart2_inference_test.dart
@@ -140,27 +140,31 @@ AssertStatement
   }
 
   test_closure_downwardReturnType_arrow() async {
-    var code = r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void main() {
   List<int> Function() g;
   g = () => 42;
+//          ^^
+// [diag.returnOfInvalidTypeFromClosure] The returned type 'int' isn't returnable from a 'List<int>' function, as required by the closure's context.
+  g;
 }
-''';
-    var result = await resolveTestCode(code);
+''');
     Expression closure = result.findNode.expression('() => 42');
     assertType(closure, 'List<int> Function()');
   }
 
   test_closure_downwardReturnType_block() async {
-    var code = r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void main() {
   List<int> Function() g;
   g = () { // mark
     return 42;
+//         ^^
+// [diag.returnOfInvalidTypeFromClosure] The returned type 'int' isn't returnable from a 'List<int>' function, as required by the closure's context.
   };
+  g;
 }
-''';
-    var result = await resolveTestCode(code);
+''');
     Expression closure = result.findNode.expression('() { // mark');
     assertType(closure, 'List<int> Function()');
   }
@@ -187,27 +191,27 @@ main() {
   }
 
   test_forIn_identifier() async {
-    var code = r'''
-T f<T>() => null;
+    var result = await resolveTestCodeWithDiagnostics(r'''
+T f<T>() => throw 0;
 
 class A {}
 
-A aTopLevel;
+late A aTopLevel;
 void set aTopLevelSetter(A value) {}
 
 class C {
-  A aField;
+  late A aField;
   void set aSetter(A value) {}
   void test() {
-    A aLocal;
+    late A aLocal;
     for (aLocal in f()) {} // local
+    aLocal;
     for (aField in f()) {} // field
     for (aSetter in f()) {} // setter
     for (aTopLevel in f()) {} // top variable
     for (aTopLevelSetter in f()) {} // top setter
   }
-}''';
-    var result = await resolveTestCode(code);
+}''');
     void assertInvocationType(String prefix) {
       var invocation = result.findNode.methodInvocation(prefix);
       assertType(invocation, 'Iterable<A>');
@@ -221,7 +225,7 @@ class C {
   }
 
   test_forIn_variable_implicitlyTyped() async {
-    var code = r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class A {}
 class B extends A {}
 
@@ -229,13 +233,22 @@ List<T> f<T extends A>(List<T> items) => items;
 
 void test(List<A> listA, List<B> listB) {
   for (var a1 in f(listA)) {} // 1
+//         ^^
+// [diag.unusedLocalVariable] The value of the local variable 'a1' isn't used.
   for (A a2 in f(listA)) {} // 2
+//       ^^
+// [diag.unusedLocalVariable] The value of the local variable 'a2' isn't used.
   for (var b1 in f(listB)) {} // 3
+//         ^^
+// [diag.unusedLocalVariable] The value of the local variable 'b1' isn't used.
   for (A b2 in f(listB)) {} // 4
+//       ^^
+// [diag.unusedLocalVariable] The value of the local variable 'b2' isn't used.
   for (B b3 in f(listB)) {} // 5
+//       ^^
+// [diag.unusedLocalVariable] The value of the local variable 'b3' isn't used.
 }
-''';
-    var result = await resolveTestCode(code);
+''');
     void assertTypes(
       String vSearch,
       String vType,
@@ -259,13 +272,12 @@ void test(List<A> listA, List<B> listB) {
   }
 
   test_implicitVoidReturnType_default() async {
-    var code = r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class C {
   set x(_) {}
   operator []=(int index, double value) => null;
 }
-''';
-    var result = await resolveTestCode(code);
+''');
     ClassElement c = result.findElement.class_('C');
 
     SetterElement x = c.setters[0];
@@ -277,16 +289,19 @@ class C {
   }
 
   test_implicitVoidReturnType_derived() async {
-    var code = r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class Base {
   dynamic set x(_) {}
+//^^^^^^^
+// [diag.nonVoidReturnForSetter] The return type of the setter must be 'void' or absent.
   dynamic operator[]=(int x, int y) => null;
+//^^^^^^^
+// [diag.nonVoidReturnForOperator] The return type of the operator []= must be 'void'.
 }
 class Derived extends Base {
   set x(_) {}
   operator[]=(int x, int y) {}
-}''';
-    var result = await resolveTestCode(code);
+}''');
     ClassElement c = result.findElement.class_('Derived');
 
     SetterElement x = c.setters[0];
@@ -298,11 +313,10 @@ class Derived extends Base {
   }
 
   test_listMap_empty() async {
-    var code = r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 var x = [];
 var y = {};
-''';
-    var result = await resolveTestCode(code);
+''');
     var xNode = result.findNode.variableDeclaration('x = ');
     var xfragment = xNode.declaredFragment!;
     assertType(xfragment.element.type, 'List<dynamic>');
@@ -313,11 +327,10 @@ var y = {};
   }
 
   test_listMap_null() async {
-    var code = r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 var x = [null];
 var y = {null: null};
-''';
-    var result = await resolveTestCode(code);
+''');
     var xNode = result.findNode.variableDeclaration('x = ');
     var xFragment = xNode.declaredFragment!;
     assertType(xFragment.element.type, 'List<Null>');
@@ -416,7 +429,7 @@ BinaryExpression
   }
 
   test_switchExpression_asContext_forCases() async {
-    var code = r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class C<T> {
   const C();
 }
@@ -428,14 +441,13 @@ void test(C<int> x) {
     default:
       break;
   }
-}''';
-    var result = await resolveTestCode(code);
+}''');
     var node = result.findNode.instanceCreation('C():');
     assertType(node, 'C<int>');
   }
 
   test_switchExpression_asContext_forCases_language219() async {
-    var code = r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 // @dart = 2.19
 class C<T> {
   const C();
@@ -448,23 +460,23 @@ void test(C<int> x) {
     default:
       break;
   }
-}''';
-    var result = await resolveTestCode(code);
+}''');
     var node = result.findNode.instanceCreation('const C():');
     assertType(node, 'C<int>');
   }
 
   test_voidType_method() async {
-    var code = r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 class C {
   void m() {}
 }
 var x = new C().m();
 main() {
   var y = new C().m();
+//    ^
+// [diag.unusedLocalVariable] The value of the local variable 'y' isn't used.
 }
-''';
-    var result = await resolveTestCode(code);
+''');
     var xNode = result.findNode.variableDeclaration('x = ');
     var xFragment = xNode.declaredFragment!;
     expect(xFragment.element.type, VoidTypeImpl.instance);
@@ -475,14 +487,15 @@ main() {
   }
 
   test_voidType_topLevelFunction() async {
-    var code = r'''
+    var result = await resolveTestCodeWithDiagnostics(r'''
 void f() {}
 var x = f();
 main() {
   var y = f();
+//    ^
+// [diag.unusedLocalVariable] The value of the local variable 'y' isn't used.
 }
-''';
-    var result = await resolveTestCode(code);
+''');
     var xNode = result.findNode.variableDeclaration('x = ');
     var xFragment = xNode.declaredFragment!;
     expect(xFragment.element.type, VoidTypeImpl.instance);