diff --git a/pkg/linter/test/rules/always_declare_return_types_test.dart b/pkg/linter/test/rules/always_declare_return_types_test.dart
index 093073c7b0f..b85c2b1dc9b 100644
--- a/pkg/linter/test/rules/always_declare_return_types_test.dart
+++ b/pkg/linter/test/rules/always_declare_return_types_test.dart
@@ -19,13 +19,13 @@ class AlwaysDeclareReturnTypesTest extends LintRuleTest {
 
   test_augmentationClass() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class A { }
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   f() { }
@@ -37,17 +37,17 @@ augment class A {
 
     result = await resolveFile(b.path);
     await assertDiagnosticsIn(errors, [
-      lint(47, 1),
+      lint(39, 1),
     ]);
   }
 
   test_augmentationTopLevelFunction() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 f() { }
 ''');
@@ -57,7 +57,7 @@ f() { }
 
     result = await resolveFile(b.path);
     await assertDiagnosticsIn(errors, [
-      lint(27, 1),
+      lint(19, 1),
     ]);
   }
 
@@ -65,7 +65,7 @@ f() { }
   /// `augmentedTopLevelFunction{*}`.
   test_augmentedMethod() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class A {
   f() { }
@@ -73,7 +73,7 @@ class A {
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment f() { }
@@ -82,7 +82,7 @@ augment class A {
 
     result = await resolveFile(a.path);
     await assertDiagnosticsIn(errors, [
-      lint(38, 1),
+      lint(28, 1),
     ]);
 
     result = await resolveFile(b.path);
@@ -91,20 +91,20 @@ augment class A {
 
   test_augmentedTopLevelFunction() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 f() { }
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment f() { }
 ''');
 
     result = await resolveFile(a.path);
     await assertDiagnosticsIn(errors, [
-      lint(26, 1),
+      lint(16, 1),
     ]);
 
     result = await resolveFile(b.path);
@@ -113,13 +113,13 @@ augment f() { }
 
   test_augmentedTopLevelFunction_chain() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 f() { }
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment dynamic f() { }
 augment f() { }
@@ -127,7 +127,7 @@ augment f() { }
 
     result = await resolveFile(a.path);
     await assertDiagnosticsIn(errors, [
-      lint(26, 1),
+      lint(16, 1),
     ]);
 
     result = await resolveFile(b.path);
diff --git a/pkg/linter/test/rules/annotate_overrides_test.dart b/pkg/linter/test/rules/annotate_overrides_test.dart
index e1bc0a4858e..fd622f7a6f4 100644
--- a/pkg/linter/test/rules/annotate_overrides_test.dart
+++ b/pkg/linter/test/rules/annotate_overrides_test.dart
@@ -24,7 +24,7 @@ class AnnotateOverridesTest extends LintRuleTest {
   )
   test_augmentationClass_implementsInterface() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 abstract interface class HasLength {
   int get length;
@@ -37,7 +37,7 @@ class C {
 
     // TODO(pq): update getter to be abstract when supported.
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class C implements HasLength {
   @override
@@ -54,7 +54,7 @@ augment class C implements HasLength {
 
   test_augmentationClass_methodWithoutAnnotation() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   void a() {}
@@ -64,19 +64,19 @@ class B extends A { }
 ''');
 
     await assertDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class B {
   void a() {}
 }
 ''', [
-      lint(52, 1),
+      lint(44, 1),
     ]);
   }
 
   test_augmentationMethodWithAnnotation() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   void a() {}
@@ -89,7 +89,7 @@ class B extends A {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class B {
   augment void a() {}
diff --git a/pkg/linter/test/rules/annotate_redeclares_test.dart b/pkg/linter/test/rules/annotate_redeclares_test.dart
index fe0292651eb..6c262832082 100644
--- a/pkg/linter/test/rules/annotate_redeclares_test.dart
+++ b/pkg/linter/test/rules/annotate_redeclares_test.dart
@@ -22,7 +22,7 @@ class AnnotateRedeclaresTest extends LintRuleTest {
 
   test_augmentationClass_method() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   void m() {}
@@ -30,20 +30,20 @@ class A {
 ''');
 
     await assertDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 extension type E(A a) implements A {
   void m() {}
 }
 ''', [
-      lint(71, 1),
+      lint(63, 1),
     ]);
   }
 
   @FailingTest(reason: 'No check that `m` is an augmentation?')
   test_augmentationMethodWithAnnotation() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 import 'package:meta/meta.dart';
 
@@ -58,7 +58,7 @@ extension type E(A a) implements A {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment extension type E(A a) {
   augment void m() { }
diff --git a/pkg/linter/test/rules/avoid_annotating_with_dynamic_test.dart b/pkg/linter/test/rules/avoid_annotating_with_dynamic_test.dart
index f56fbffec93..4f8f76ece61 100644
--- a/pkg/linter/test/rules/avoid_annotating_with_dynamic_test.dart
+++ b/pkg/linter/test/rules/avoid_annotating_with_dynamic_test.dart
@@ -19,13 +19,13 @@ class AvoidAnnotatingWithDynamicTest extends LintRuleTest {
 
   test_augmentationClass() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class A { }
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   void f(dynamic o) { }
@@ -37,17 +37,17 @@ augment class A {
 
     result = await resolveFile(b.path);
     await assertDiagnosticsIn(errors, [
-      lint(54, 9),
+      lint(46, 9),
     ]);
   }
 
   test_augmentationTopLevelFunction() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 void f(dynamic o) { }
 ''');
@@ -57,19 +57,19 @@ void f(dynamic o) { }
 
     result = await resolveFile(b.path);
     await assertDiagnosticsIn(errors, [
-      lint(34, 9),
+      lint(26, 9),
     ]);
   }
 
   test_augmentationTopLevelFunction_localDynamic() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 void f(int i) {}
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment void f(int i) {
   var g = (dynamic x) {};
@@ -82,13 +82,13 @@ augment void f(int i) {
 
     result = await resolveFile(b.path);
     await assertDiagnosticsIn(errors, [
-      lint(62, 9),
+      lint(54, 9),
     ]);
   }
 
   test_augmentedMethod() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class A {
   void f(dynamic o) { }
@@ -96,7 +96,7 @@ class A {
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment void f(dynamic o) { }
@@ -105,7 +105,7 @@ augment class A {
 
     result = await resolveFile(a.path);
     await assertDiagnosticsIn(errors, [
-      lint(45, 9),
+      lint(35, 9),
     ]);
 
     result = await resolveFile(b.path);
@@ -114,20 +114,20 @@ augment class A {
 
   test_augmentedTopLevelFunction() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 void f(dynamic o) { }
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment void f(dynamic o) { }
 ''');
 
     result = await resolveFile(a.path);
     await assertDiagnosticsIn(errors, [
-      lint(33, 9),
+      lint(23, 9),
     ]);
 
     result = await resolveFile(b.path);
@@ -136,13 +136,13 @@ augment void f(dynamic o) { }
 
   test_augmentedTopLevelFunction_multiple() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 void f(dynamic o) { }
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment void f(dynamic o) { }
 augment void f(dynamic o) { }
@@ -150,7 +150,7 @@ augment void f(dynamic o) { }
 
     result = await resolveFile(a.path);
     await assertDiagnosticsIn(errors, [
-      lint(33, 9),
+      lint(23, 9),
     ]);
 
     result = await resolveFile(b.path);
diff --git a/pkg/linter/test/rules/avoid_classes_with_only_static_members_test.dart b/pkg/linter/test/rules/avoid_classes_with_only_static_members_test.dart
index 31816cb9e8c..b5f84a9ad3e 100644
--- a/pkg/linter/test/rules/avoid_classes_with_only_static_members_test.dart
+++ b/pkg/linter/test/rules/avoid_classes_with_only_static_members_test.dart
@@ -19,7 +19,7 @@ class AvoidClassesWithOnlyStaticMembers extends LintRuleTest {
 
   test_augmentationClass_nonStaticField() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class A {
   static int f = 1;
@@ -28,7 +28,7 @@ class A {
 
     // The added field should prevent a lint above.
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A { 
   int a = 1;
@@ -44,13 +44,13 @@ augment class A {
 
   test_augmentationClass_staticField() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class A {}
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A { 
   static int f = 1;
@@ -59,7 +59,7 @@ augment class A {
 
     result = await resolveFile(a.path);
     await assertDiagnosticsIn(errors, [
-      lint(26, 10),
+      lint(16, 10),
     ]);
 
     result = await resolveFile(b.path);
@@ -68,13 +68,13 @@ augment class A {
 
   test_augmentationClass_staticMethod() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class A {}
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A { 
   static void m() {}
@@ -83,7 +83,7 @@ augment class A {
 
     result = await resolveFile(a.path);
     await assertDiagnosticsIn(errors, [
-      lint(26, 10),
+      lint(16, 10),
     ]);
 
     result = await resolveFile(b.path);
@@ -108,13 +108,13 @@ class C {}
 
   test_class_empty_augmentation_empty() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class A {}
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {}
 ''');
diff --git a/pkg/linter/test/rules/avoid_equals_and_hash_code_on_mutable_classes_test.dart b/pkg/linter/test/rules/avoid_equals_and_hash_code_on_mutable_classes_test.dart
index 3d0ce8c14f2..de3326a7eb7 100644
--- a/pkg/linter/test/rules/avoid_equals_and_hash_code_on_mutable_classes_test.dart
+++ b/pkg/linter/test/rules/avoid_equals_and_hash_code_on_mutable_classes_test.dart
@@ -58,13 +58,13 @@ class A {
       issue: 'https://github.com/dart-lang/linter/issues/4932')
   test_immutableClass_augmented() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class A {}
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 import 'package:meta/meta.dart';
 
@@ -102,7 +102,7 @@ class A {
 
   test_mutableClass_augmentationMethod() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   @override
@@ -111,7 +111,7 @@ class A {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment int get hashCode => 0;
@@ -121,20 +121,20 @@ augment class A {
 
   test_mutableClass_augmented() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {}
 ''');
 
     await assertDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   @override
   int get hashCode => 0;
 }
 ''', [
-      lint(59, 3),
+      lint(51, 3),
     ]);
   }
 
diff --git a/pkg/linter/test/rules/avoid_field_initializers_in_non_const_classes_test.dart b/pkg/linter/test/rules/avoid_field_initializers_in_non_const_classes_test.dart
index 1268fbb868f..20631bdbd88 100644
--- a/pkg/linter/test/rules/avoid_field_initializers_in_non_const_classes_test.dart
+++ b/pkg/linter/test/rules/avoid_field_initializers_in_non_const_classes_test.dart
@@ -19,7 +19,7 @@ class AvoidFieldInitializersInConstClassesTest extends LintRuleTest {
 
   test_augmentationClass_nonConstConstructor() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class A {
   final a;
@@ -28,7 +28,7 @@ class A {
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A { 
   A.aa() : a = 1;
@@ -44,7 +44,7 @@ augment class A {
 
   test_augmentedClass_augmentedConstructor() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   const A();
@@ -53,19 +53,19 @@ class A {
 ''');
 
     await assertDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment const A() : s = '';
 }
 ''', [
-      lint(67, 6),
+      lint(59, 6),
     ]);
   }
 
   test_augmentedClass_augmentedField() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   const A();
@@ -74,7 +74,7 @@ class A {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment final s = '';
@@ -84,26 +84,26 @@ augment class A {
 
   test_augmentedClass_constructorInitializer() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A { }
 ''');
 
     await assertDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   final a;
   const A() : a = '';
 }
 ''', [
-      lint(70, 6),
+      lint(62, 6),
     ]);
   }
 
   test_augmentedClass_constructorInitializer_multipleConstructors() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A { 
   A.aa();
@@ -111,7 +111,7 @@ class A {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   final a;
@@ -122,7 +122,7 @@ augment class A {
 
   test_augmentedClass_field() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A { 
   const A();
@@ -130,13 +130,13 @@ class A {
 ''');
 
     await assertDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   final s = '';
 }
 ''', [
-      lint(53, 6),
+      lint(45, 6),
     ]);
   }
 }
diff --git a/pkg/linter/test/rules/avoid_positional_boolean_parameters_test.dart b/pkg/linter/test/rules/avoid_positional_boolean_parameters_test.dart
index 39d9e8f70b5..927cabb399c 100644
--- a/pkg/linter/test/rules/avoid_positional_boolean_parameters_test.dart
+++ b/pkg/linter/test/rules/avoid_positional_boolean_parameters_test.dart
@@ -27,7 +27,7 @@ void f(List<bool> list) {
 
   test_augmentationConstructor() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   A(bool b);
@@ -35,7 +35,7 @@ class A {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment A(bool b);
@@ -45,13 +45,13 @@ augment class A {
 
   test_augmentationFunction() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 void f(bool b) { }
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment void f(bool b) { }
 ''');
@@ -59,7 +59,7 @@ augment void f(bool b) { }
 
   test_augmentationMethod() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   void f(bool b) { }
@@ -67,7 +67,7 @@ class A {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment void f(bool b) { }
diff --git a/pkg/linter/test/rules/avoid_renaming_method_parameters_test.dart b/pkg/linter/test/rules/avoid_renaming_method_parameters_test.dart
index 47c0b39603d..cab28ed71ee 100644
--- a/pkg/linter/test/rules/avoid_renaming_method_parameters_test.dart
+++ b/pkg/linter/test/rules/avoid_renaming_method_parameters_test.dart
@@ -29,13 +29,13 @@ class AvoidRenamingMethodParametersTest extends LintRuleTest {
       issue: 'https://github.com/dart-lang/linter/issues/4891')
   test_augmentedFunction() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 void f(int p) {}
 ''');
 
     await assertDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment void f(int q) {}
 ''', [
@@ -45,7 +45,7 @@ augment void f(int q) {}
 
   test_augmentedMethod() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   void m(int p) {}
@@ -53,14 +53,14 @@ class A {
 ''');
 
     await assertDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment void m(int q) {}
   augment void m(int q) {} 
 }
 ''', [
-      lint(66, 1), // Only the first augmentation gets linted.
+      lint(58, 1), // Only the first augmentation gets linted.
     ]);
   }
 
diff --git a/pkg/linter/test/rules/avoid_unused_constructor_parameters_test.dart b/pkg/linter/test/rules/avoid_unused_constructor_parameters_test.dart
index 9f8d5598df0..30bb7bf6cd7 100644
--- a/pkg/linter/test/rules/avoid_unused_constructor_parameters_test.dart
+++ b/pkg/linter/test/rules/avoid_unused_constructor_parameters_test.dart
@@ -19,25 +19,25 @@ class AvoidUnusedConstructorParametersTest extends LintRuleTest {
 
   test_augmentationClass() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A { }
 ''');
 
     await assertDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   A(int a);
 }
 ''', [
-      lint(49, 5),
+      lint(41, 5),
     ]);
   }
 
   test_augmentedConstructor() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   A(int a);
@@ -45,7 +45,7 @@ class A {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment A.new(int a);
diff --git a/pkg/linter/test/rules/camel_case_extensions_test.dart b/pkg/linter/test/rules/camel_case_extensions_test.dart
index 479937d9e6b..44939393dbf 100644
--- a/pkg/linter/test/rules/camel_case_extensions_test.dart
+++ b/pkg/linter/test/rules/camel_case_extensions_test.dart
@@ -19,13 +19,13 @@ class CamelCaseExtensionsTest extends LintRuleTest {
 
   test_augmentationExtension_lowerCase() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 extension e on Object { }
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment extension e { }
 ''');
diff --git a/pkg/linter/test/rules/camel_case_types_test.dart b/pkg/linter/test/rules/camel_case_types_test.dart
index dabc16e5316..367ec0c14d6 100644
--- a/pkg/linter/test/rules/camel_case_types_test.dart
+++ b/pkg/linter/test/rules/camel_case_types_test.dart
@@ -19,13 +19,13 @@ class CamelCaseTypesTest extends LintRuleTest {
 
   test_augmentationClass_lowerCase() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class a {}
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class a {}
 ''');
@@ -33,7 +33,7 @@ augment class a {}
 
   test_augmentationEnum_lowerCase() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 enum e {
   a;
@@ -41,7 +41,7 @@ enum e {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment enum e {
   b;
@@ -51,13 +51,13 @@ augment enum e {
 
   test_augmentationExtensionType_lowerCase() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 extension type et(int i) {}
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment extension type et(int i) {}
 ''');
@@ -65,13 +65,13 @@ augment extension type et(int i) {}
 
   test_augmentationMixin_lowerCase() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 mixin m {}
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment mixin m {}
 ''');
diff --git a/pkg/linter/test/rules/constant_identifier_names_test.dart b/pkg/linter/test/rules/constant_identifier_names_test.dart
index c8abf766325..74d99e09c70 100644
--- a/pkg/linter/test/rules/constant_identifier_names_test.dart
+++ b/pkg/linter/test/rules/constant_identifier_names_test.dart
@@ -19,7 +19,7 @@ class ConstantIdentifierNamesTest extends LintRuleTest {
 
   test_augmentationEnum() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 enum E {
   a;
@@ -27,33 +27,33 @@ enum E {
 ''');
 
     await assertDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment enum E {
   Xy;
 }
 ''', [
-      lint(46, 2),
+      lint(38, 2),
     ]);
   }
 
   test_augmentationTopLevelVariable() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 ''');
 
     await assertDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 const PI = 3.14;
 ''', [
-      lint(33, 2),
+      lint(25, 2),
     ]);
   }
 
   test_augmentedEnumValue() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 enum E {
   Xy;
@@ -61,7 +61,7 @@ enum E {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment enum E {
   augment Xy;
@@ -71,13 +71,13 @@ augment enum E {
 
   test_augmentedTopLevelVariable() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 const PI = 3.14;
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment const PI = 3.1415;
 ''');
diff --git a/pkg/linter/test/rules/hash_and_equals_test.dart b/pkg/linter/test/rules/hash_and_equals_test.dart
index f01224932f3..05d235b7260 100644
--- a/pkg/linter/test/rules/hash_and_equals_test.dart
+++ b/pkg/linter/test/rules/hash_and_equals_test.dart
@@ -19,7 +19,7 @@ class HashAndEqualsTest extends LintRuleTest {
 
   test_augmentedClass_augmentation() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   int get hashCode => 0;
@@ -27,7 +27,7 @@ class A {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   bool operator ==(Object other) => false;
@@ -37,19 +37,19 @@ augment class A {
 
   test_augmentedClass_augmentation_missingHash() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A { }
 ''');
 
     await assertDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   bool operator ==(Object other) => false;
 }
 ''', [
-      lint(61, 2),
+      lint(53, 2),
     ]);
   }
 
diff --git a/pkg/linter/test/rules/non_constant_identifier_names_test.dart b/pkg/linter/test/rules/non_constant_identifier_names_test.dart
index 88f336ef10d..d094e045ab5 100644
--- a/pkg/linter/test/rules/non_constant_identifier_names_test.dart
+++ b/pkg/linter/test/rules/non_constant_identifier_names_test.dart
@@ -224,7 +224,7 @@ class NonConstantIdentifierNamesTest extends LintRuleTest {
 
   test_augmentedConstructor() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   A.Aa();
@@ -232,7 +232,7 @@ class A {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment A.Aa();
@@ -242,7 +242,7 @@ augment class A {
 
   test_augmentedField() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   int Xx = 1;
@@ -250,7 +250,7 @@ class A {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment int Xx = 2;
@@ -260,13 +260,13 @@ augment class A {
 
   test_augmentedFunction() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 void Ff() { }
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment void Ff() { }
 ''');
@@ -274,13 +274,13 @@ augment void Ff() { }
 
   test_augmentedFunction_namedParam() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 void f({String? Ss}) { }
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment void f({String? Ss}) { }
 ''');
@@ -288,24 +288,24 @@ augment void f({String? Ss}) { }
 
   test_augmentedFunction_positionalParam() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 void f(String? Ss, [int? Xx]) { }
 ''');
 
     await assertDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment void f(String? Ss, [int? Xx]) { }
 ''', [
-      lint(50, 2),
-      lint(60, 2),
+      lint(42, 2),
+      lint(52, 2),
     ]);
   }
 
   test_augmentedGetter() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   int get Gg => 1;
@@ -313,7 +313,7 @@ class A {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment int get Gg => 2;
@@ -323,7 +323,7 @@ augment class A {
 
   test_augmentedMethod() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   void Mm() { }
@@ -331,7 +331,7 @@ class A {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment void Mm() { }
@@ -341,7 +341,7 @@ augment class A {
 
   test_augmentedMethod_namedParam() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   void m({String? Ss}) { }
@@ -349,7 +349,7 @@ class A {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment void m({String? Ss}) { }
@@ -359,7 +359,7 @@ augment class A {
 
   test_augmentedMethod_positionalParam() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   void m(String? Ss, [int? Xx]) { }
@@ -367,26 +367,26 @@ class A {
 ''');
 
     await assertDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment void m(String? Ss, [int? Xx]) { }
 }
 ''', [
-      lint(70, 2),
-      lint(80, 2),
+      lint(62, 2),
+      lint(72, 2),
     ]);
   }
 
   test_augmentedTopLevelVariable() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 int Xx = 1;
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment int Xx = 2;
 ''');
diff --git a/pkg/linter/test/rules/one_member_abstracts_test.dart b/pkg/linter/test/rules/one_member_abstracts_test.dart
index 3bc96106335..a24870aa763 100644
--- a/pkg/linter/test/rules/one_member_abstracts_test.dart
+++ b/pkg/linter/test/rules/one_member_abstracts_test.dart
@@ -59,13 +59,13 @@ mixin M {
 
   test_oneMember_augmentedAbstractClass_augmentation() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 abstract class A { }
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment abstract class A {
   void m();
@@ -75,7 +75,7 @@ augment abstract class A {
 
   test_oneMember_augmentedAbstractClass_declaration() async {
     newFile('$testPackageLibPath/a.dart', r'''
-augment library 'test.dart';
+part of 'test.dart';
 
 augment abstract class A {
   void m();
@@ -83,11 +83,11 @@ augment abstract class A {
 ''');
 
     await assertDiagnostics(r'''
-import augment 'a.dart';
+part 'a.dart';
 
 abstract class A { }
 ''', [
-      lint(41, 1),
+      lint(31, 1),
     ]);
   }
 
@@ -142,7 +142,7 @@ sealed class C {
 
   test_twoMembers_augmentedAbstractClass_declaration() async {
     newFile('$testPackageLibPath/a.dart', r'''
-augment library 'test.dart';
+part of 'test.dart';
 
 augment abstract class A {
   void m();
@@ -150,7 +150,7 @@ augment abstract class A {
 ''');
 
     newFile('$testPackageLibPath/b.dart', r'''
-augment library 'test.dart';
+part of 'test.dart';
 
 augment abstract class A {
   void n();
@@ -158,8 +158,8 @@ augment abstract class A {
 ''');
 
     await assertNoDiagnostics(r'''
-import augment 'a.dart';
-import augment 'b.dart';
+part 'a.dart';
+part 'b.dart';
 
 abstract class A { }
 ''');
diff --git a/pkg/linter/test/rules/overridden_fields_test.dart b/pkg/linter/test/rules/overridden_fields_test.dart
index 82729c93d1b..3c8203fb3a4 100644
--- a/pkg/linter/test/rules/overridden_fields_test.dart
+++ b/pkg/linter/test/rules/overridden_fields_test.dart
@@ -19,7 +19,7 @@ class OverriddenFieldsTest extends LintRuleTest {
 
   test_augmentationClass() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class O {
   final a = '';
@@ -29,7 +29,7 @@ class A extends O { }
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A { 
   final a = '';
@@ -41,13 +41,13 @@ augment class A {
 
     result = await resolveFile(b.path);
     await assertDiagnosticsIn(errors, [
-      lint(54, 1),
+      lint(46, 1),
     ]);
   }
 
   test_augmentedField() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class O {
   final a = '';
@@ -60,7 +60,7 @@ class A extends O {
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A { 
   augment final a = '';
@@ -69,7 +69,7 @@ augment class A {
 
     result = await resolveFile(a.path);
     await assertDiagnosticsIn(errors, [
-      lint(96, 1),
+      lint(86, 1),
     ]);
 
     result = await resolveFile(b.path);
diff --git a/pkg/linter/test/rules/prefer_generic_function_type_aliases_test.dart b/pkg/linter/test/rules/prefer_generic_function_type_aliases_test.dart
index 078d387d42b..2fe0394f64d 100644
--- a/pkg/linter/test/rules/prefer_generic_function_type_aliases_test.dart
+++ b/pkg/linter/test/rules/prefer_generic_function_type_aliases_test.dart
@@ -23,13 +23,13 @@ class PreferGenericFunctionTypeAliasesTest extends LintRuleTest {
 ''', issue: 'https://github.com/dart-lang/linter/issues/4942')
   test_augmentedTypeAlias() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 typedef void F();
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment typedef void F();
 ''');
diff --git a/pkg/linter/test/rules/prefer_typing_uninitialized_variables_test.dart b/pkg/linter/test/rules/prefer_typing_uninitialized_variables_test.dart
index e9c5a88902a..a3c35854694 100644
--- a/pkg/linter/test/rules/prefer_typing_uninitialized_variables_test.dart
+++ b/pkg/linter/test/rules/prefer_typing_uninitialized_variables_test.dart
@@ -19,7 +19,7 @@ class PreferTypingUninitializedVariablesTest extends LintRuleTest {
 
   test_field_augmented() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class A {
   var x;
@@ -27,7 +27,7 @@ class A {
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment var x;
@@ -36,7 +36,7 @@ augment class A {
 
     result = await resolveFile(a.path);
     await assertDiagnosticsIn(errors, [
-      lint(42, 1),
+      lint(32, 1),
     ]);
 
     result = await resolveFile(b.path);
@@ -133,20 +133,20 @@ void f() {
 
   test_topLevelVariable_augmented() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 var x;
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment var x;
 ''');
 
     result = await resolveFile(a.path);
     await assertDiagnosticsIn(errors, [
-      lint(30, 1),
+      lint(20, 1),
     ]);
 
     result = await resolveFile(b.path);
diff --git a/pkg/linter/test/rules/prefer_void_to_null_test.dart b/pkg/linter/test/rules/prefer_void_to_null_test.dart
index 00d8a85d0f4..eae8d0ce3ee 100644
--- a/pkg/linter/test/rules/prefer_void_to_null_test.dart
+++ b/pkg/linter/test/rules/prefer_void_to_null_test.dart
@@ -19,7 +19,7 @@ class PreferVoidToNullTest extends LintRuleTest {
 
   test_augmentedField() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   Future<Null>? f;
@@ -27,7 +27,7 @@ class A {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment Future<Null>? f;
@@ -37,13 +37,13 @@ augment class A {
 
   test_augmentedFunction() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 Future<Null>? f() => null;
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment Future<Null>? f() => null;
 ''');
@@ -51,7 +51,7 @@ augment Future<Null>? f() => null;
 
   test_augmentedGetter() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   Future<Null>? get v => null;
@@ -59,7 +59,7 @@ class A {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment Future<Null>? get v => null;
@@ -69,7 +69,7 @@ augment class A {
 
   test_augmentedMethod() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 class A {
   Future<Null>? f() => null;
@@ -77,7 +77,7 @@ class A {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment Future<Null>? f() => null;
@@ -87,13 +87,13 @@ augment class A {
 
   test_augmentedTopLevelGetter() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 Future<Null>? get v => null;
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment Future<Null>? get v => null;
 ''');
@@ -101,13 +101,13 @@ augment Future<Null>? get v => null;
 
   test_augmentedTopLevelVariable() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
+part 'test.dart';
 
 Future<Null>? v;
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment Future<Null>? v;
 ''');
diff --git a/pkg/linter/test/rules/type_annotate_public_apis_test.dart b/pkg/linter/test/rules/type_annotate_public_apis_test.dart
index 3282f380c2f..06a091d2b64 100644
--- a/pkg/linter/test/rules/type_annotate_public_apis_test.dart
+++ b/pkg/linter/test/rules/type_annotate_public_apis_test.dart
@@ -21,13 +21,13 @@ class TypeAnnotatePublicApisTest extends LintRuleTest {
 
   test_augmentationClass_field() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class A { }
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   var i;
@@ -39,19 +39,19 @@ augment class A {
 
     result = await resolveFile(b.path);
     await assertDiagnosticsIn(errors, [
-      lint(51, 1),
+      lint(43, 1),
     ]);
   }
 
   test_augmentationClass_method() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class A { }
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   void f(x) { }
@@ -63,17 +63,17 @@ augment class A {
 
     result = await resolveFile(b.path);
     await assertDiagnosticsIn(errors, [
-      lint(54, 1),
+      lint(46, 1),
     ]);
   }
 
   test_augmentationTopLevelFunction() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 void f(x) { }
 ''');
@@ -83,17 +83,17 @@ void f(x) { }
 
     result = await resolveFile(b.path);
     await assertDiagnosticsIn(errors, [
-      lint(34, 1),
+      lint(26, 1),
     ]);
   }
 
   test_augmentationTopLevelVariable() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 var x;
 ''');
@@ -103,13 +103,13 @@ var x;
 
     result = await resolveFile(b.path);
     await assertDiagnosticsIn(errors, [
-      lint(31, 1),
+      lint(23, 1),
     ]);
   }
 
   test_augmentedField() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class A {
   var x;
@@ -117,7 +117,7 @@ class A {
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment var x;
@@ -126,7 +126,7 @@ augment class A {
 
     result = await resolveFile(a.path);
     await assertDiagnosticsIn(errors, [
-      lint(42, 1),
+      lint(32, 1),
     ]);
 
     result = await resolveFile(b.path);
@@ -135,7 +135,7 @@ augment class A {
 
   test_augmentedMethod() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class A {
   void f(x) { }
@@ -143,7 +143,7 @@ class A {
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   augment void f(x) { }
@@ -152,7 +152,7 @@ augment class A {
 
     result = await resolveFile(a.path);
     await assertDiagnosticsIn(errors, [
-      lint(45, 1),
+      lint(35, 1),
     ]);
 
     result = await resolveFile(b.path);
@@ -161,20 +161,20 @@ augment class A {
 
   test_augmentedTopLevelFunction() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 void f(x) { }
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment void f(x) { }
 ''');
 
     result = await resolveFile(a.path);
     await assertDiagnosticsIn(errors, [
-      lint(33, 1),
+      lint(23, 1),
     ]);
 
     result = await resolveFile(b.path);
@@ -183,20 +183,20 @@ augment void f(x) { }
 
   test_augmentedTopLevelVariable() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 var x;
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment var x;
 ''');
 
     result = await resolveFile(a.path);
     await assertDiagnosticsIn(errors, [
-      lint(30, 1),
+      lint(20, 1),
     ]);
 
     result = await resolveFile(b.path);
diff --git a/pkg/linter/test/rules/unnecessary_getters_setters_test.dart b/pkg/linter/test/rules/unnecessary_getters_setters_test.dart
index 601f072c753..fca4fdbb108 100644
--- a/pkg/linter/test/rules/unnecessary_getters_setters_test.dart
+++ b/pkg/linter/test/rules/unnecessary_getters_setters_test.dart
@@ -79,13 +79,13 @@ class C {
   @FailingTest(issue: 'https://github.com/dart-lang/linter/issues/4935')
   test_unnecessary_augmentationAddedGetterAndSetter() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class A {}
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   String? _x;
@@ -110,7 +110,7 @@ augment class A {
   @FailingTest(issue: 'https://github.com/dart-lang/linter/issues/4935')
   test_unnecessary_augmentationAddedSetter() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class A {
   String? _x;
@@ -120,7 +120,7 @@ class A {
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   set x(String? value) {
diff --git a/pkg/linter/test/rules/unnecessary_overrides_test.dart b/pkg/linter/test/rules/unnecessary_overrides_test.dart
index 061d9785fa9..79c93a201a5 100644
--- a/pkg/linter/test/rules/unnecessary_overrides_test.dart
+++ b/pkg/linter/test/rules/unnecessary_overrides_test.dart
@@ -36,13 +36,13 @@ class C extends A {
 
   test_class_augmentation_method_withoutOverride_noSuper() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class A {}
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class A {
   void foo() {}
diff --git a/pkg/linter/test/rules/use_enums_test.dart b/pkg/linter/test/rules/use_enums_test.dart
index 926dc4d30fa..934cfe15b50 100644
--- a/pkg/linter/test/rules/use_enums_test.dart
+++ b/pkg/linter/test/rules/use_enums_test.dart
@@ -19,13 +19,13 @@ class UseEnumsTest extends LintRuleTest {
 
   test_augmentation() async {
     var a = newFile('$testPackageLibPath/a.dart', r'''
-import augment 'b.dart';
+part 'b.dart';
 
 class C {}
 ''');
 
     var b = newFile('$testPackageLibPath/b.dart', r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 augment class C {
   static const a = C._(1);
diff --git a/pkg/linter/test/rules/use_key_in_widget_constructors_test.dart b/pkg/linter/test/rules/use_key_in_widget_constructors_test.dart
index 831b60813be..cd6446b2a14 100644
--- a/pkg/linter/test/rules/use_key_in_widget_constructors_test.dart
+++ b/pkg/linter/test/rules/use_key_in_widget_constructors_test.dart
@@ -22,8 +22,8 @@ class UseKeyInWidgetConstructorsTest extends LintRuleTest {
 
   test_augmentedConstructor_noKey() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
 import 'package:flutter/widgets.dart';
+part 'test.dart';
 
 class W extends StatelessWidget {
   W();
@@ -34,7 +34,7 @@ class W extends StatelessWidget {
 ''');
 
     await assertNoDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 import 'package:flutter/widgets.dart';
 
@@ -58,8 +58,8 @@ abstract class MyWidget extends StatelessWidget {
 
   test_constructorInAugmentedClass() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
 import 'package:flutter/widgets.dart';
+part 'test.dart';
 
 class W extends StatelessWidget {
   @override
@@ -68,7 +68,7 @@ class W extends StatelessWidget {
 ''');
 
     await assertDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 import 'package:flutter/widgets.dart';
 
@@ -78,14 +78,14 @@ augment class W {
   const W({Key? key});
 }
 ''', [
-      lint(114, 1),
+      lint(106, 1),
     ]);
   }
 
   test_constructorInAugmentedClass_noKeyParam() async {
     newFile('$testPackageLibPath/a.dart', r'''
-import augment 'test.dart';
 import 'package:flutter/widgets.dart';
+part 'test.dart';
 
 class W extends StatelessWidget {
   @override
@@ -94,7 +94,7 @@ class W extends StatelessWidget {
 ''');
 
     await assertDiagnostics(r'''
-augment library 'a.dart';
+part of 'a.dart';
 
 import 'package:flutter/widgets.dart';
 
@@ -102,7 +102,7 @@ augment class W {
   const W();
 }
 ''', [
-      lint(93, 1),
+      lint(85, 1),
     ]);
   }
 
@@ -133,7 +133,7 @@ class MyWidget extends StatelessWidget {
 
   test_keyUse_inAugmentedConstructor() async {
     newFile('$testPackageLibPath/a.dart', r'''
-augment library 'test.dart';
+part of 'test.dart';
 
 import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
@@ -144,8 +144,8 @@ augment class W {
 ''');
 
     await assertNoDiagnostics(r'''
-import augment 'a.dart';
 import 'package:flutter/widgets.dart';
+part 'a.dart';
 
 class W extends StatelessWidget {
   @override