diff --git a/pkg/_fe_analyzer_shared/lib/src/parser/parser_impl.dart b/pkg/_fe_analyzer_shared/lib/src/parser/parser_impl.dart
index 8be4b88114a..0a4ab68b5bd 100644
--- a/pkg/_fe_analyzer_shared/lib/src/parser/parser_impl.dart
+++ b/pkg/_fe_analyzer_shared/lib/src/parser/parser_impl.dart
@@ -6189,7 +6189,7 @@ class Parser {
       token = parseFunctionBody(
         token,
         /* ofFunctionExpression = */ false,
-        /* allowAbstract = */ false,
+        /* allowAbstract = */ _isAugmentationsFeatureEnabled,
       );
     }
     switch (kind) {
diff --git a/pkg/analyzer/test/generated/error_parser_test.dart b/pkg/analyzer/test/generated/error_parser_test.dart
index 657362b5c72..2c28d0a045f 100644
--- a/pkg/analyzer/test/generated/error_parser_test.dart
+++ b/pkg/analyzer/test/generated/error_parser_test.dart
@@ -1335,6 +1335,7 @@ class C {
     ]);
   }
 
+  @FailingTest() // TODO(scheglov): implement augmentation
   void test_factoryWithoutBody() {
     var parseResult = parseStringWithErrors(r'''
 class C {
@@ -1344,6 +1345,16 @@ class C {
     parseResult.assertErrors([error(diag.missingFunctionBody, 23, 1)]);
   }
 
+  void test_factoryWithoutBody_language305() {
+    var parseResult = parseStringWithErrors(r'''
+// @dart = 3.5
+class C {
+  factory C();
+}
+''');
+    parseResult.assertErrors([error(diag.missingFunctionBody, 38, 1)]);
+  }
+
   void test_fieldInitializerOutsideConstructor() {
     var parseResult = parseStringWithErrors(r'''
 class C {
diff --git a/pkg/analyzer/test/src/dart/parser/class_test.dart b/pkg/analyzer/test/src/dart/parser/class_test.dart
index 23fa3788fdc..341d9cde9d8 100644
--- a/pkg/analyzer/test/src/dart/parser/class_test.dart
+++ b/pkg/analyzer/test/src/dart/parser/class_test.dart
@@ -879,6 +879,53 @@ ConstructorDeclaration
 ''');
   }
 
+  test_constructor_typeName_factory_unnamed_noBody() {
+    var parseResult = parseStringWithErrors(r'''
+class A {
+  factory A();
+}
+''');
+    parseResult.assertExpectedDiagnostics();
+
+    var node = parseResult.findNode.singleConstructorDeclaration;
+    assertParsedNodeText(node, r'''
+ConstructorDeclaration
+  factoryKeyword: factory
+  typeName: SimpleIdentifier
+    token: A
+  parameters: FormalParameterList
+    leftParenthesis: (
+    rightParenthesis: )
+  body: EmptyFunctionBody
+    semicolon: ;
+''');
+  }
+
+  test_constructor_typeName_factory_unnamed_noBody_language305() {
+    var parseResult = parseStringWithErrors(r'''
+// @dart = 3.5
+class A {
+  factory A();
+//           ^
+// [diag.missingFunctionBody] A function body must be provided.
+}
+''');
+    parseResult.assertExpectedDiagnostics();
+
+    var node = parseResult.findNode.singleConstructorDeclaration;
+    assertParsedNodeText(node, r'''
+ConstructorDeclaration
+  factoryKeyword: factory
+  typeName: SimpleIdentifier
+    token: A
+  parameters: FormalParameterList
+    leftParenthesis: (
+    rightParenthesis: )
+  body: EmptyFunctionBody
+    semicolon: ;
+''');
+  }
+
   test_constructor_typeName_factory_unnamed_withoutPrimaryConstructors() {
     var parseResult = parseStringWithErrors(r'''
 // @dart = 3.10
diff --git a/pkg/analyzer/test/src/diagnostics/constructor_already_complete_test.dart b/pkg/analyzer/test/src/diagnostics/constructor_already_complete_test.dart
index 4016507554b..e390a70713e 100644
--- a/pkg/analyzer/test/src/diagnostics/constructor_already_complete_test.dart
+++ b/pkg/analyzer/test/src/diagnostics/constructor_already_complete_test.dart
@@ -55,7 +55,6 @@ class A {
     );
   }
 
-  @FailingTest() // TODO(scheglov): implement augmentation
   test_secondary_factory_introductory_noBody() async {
     await assertNoErrorsInCode(r'''
 class A {
diff --git a/pkg/analyzer/test/src/diagnostics/constructor_body_test.dart b/pkg/analyzer/test/src/diagnostics/constructor_body_test.dart
index 162e921498e..9868d269e84 100644
--- a/pkg/analyzer/test/src/diagnostics/constructor_body_test.dart
+++ b/pkg/analyzer/test/src/diagnostics/constructor_body_test.dart
@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+import 'package:analyzer/src/diagnostic/diagnostic.dart' as diag;
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../dart/resolution/context_collection_resolution.dart';
@@ -109,6 +110,7 @@ class C {
 ''');
   }
 
+  @SkippedTest() // TODO(scheglov): implement augmentation
   test_class_secondaryConstructor_constFactory_emptyBody() async {
     await resolveTestCodeWithDiagnostics(r'''
 class C {
@@ -121,6 +123,18 @@ class C {
 ''');
   }
 
+  test_class_secondaryConstructor_constFactory_emptyBody_language305() async {
+    await assertErrorsInCode(
+      r'''
+// @dart = 3.5
+class C {
+  const factory C();
+}
+''',
+      [error(diag.constFactory, 27, 5), error(diag.missingFunctionBody, 44, 1)],
+    );
+  }
+
   test_class_secondaryConstructor_constFactory_expressionBody() async {
     await resolveTestCodeWithDiagnostics(r'''
 class C {
@@ -470,6 +484,7 @@ enum E {
 ''');
   }
 
+  @SkippedTest() // TODO(scheglov): implement augmentation
   test_enum_secondaryConstructor_constFactory_emptyBody() async {
     await resolveTestCodeWithDiagnostics(r'''
 enum E {
@@ -484,6 +499,20 @@ enum E {
 ''');
   }
 
+  test_enum_secondaryConstructor_constFactory_emptyBody_language305() async {
+    await assertErrorsInCode(
+      r'''
+// @dart = 3.5
+enum E {
+  v;
+  const E();
+  const factory E.named();
+}
+''',
+      [error(diag.constFactory, 44, 5), error(diag.missingFunctionBody, 67, 1)],
+    );
+  }
+
   test_enum_secondaryConstructor_constFactory_expressionBody() async {
     await resolveTestCodeWithDiagnostics(r'''
 enum E {
@@ -804,6 +833,7 @@ extension type const E(int it) {
 ''');
   }
 
+  @SkippedTest() // TODO(scheglov): implement augmentation
   test_extensionType_secondaryConstructor_constFactory_emptyBody() async {
     await resolveTestCodeWithDiagnostics(r'''
 extension type const E(int it) {
@@ -816,6 +846,18 @@ extension type const E(int it) {
 ''');
   }
 
+  test_extensionType_secondaryConstructor_constFactory_emptyBody_language305() async {
+    await assertErrorsInCode(
+      r'''
+// @dart = 3.5
+extension type const E(int it) {
+  const factory E.named();
+}
+''',
+      [error(diag.constFactory, 50, 5), error(diag.missingFunctionBody, 73, 1)],
+    );
+  }
+
   test_extensionType_secondaryConstructor_constFactory_expressionBody() async {
     await resolveTestCodeWithDiagnostics(r'''
 extension type const E(int it) {
diff --git a/pkg/analyzer/test/src/diagnostics/field_initializer_factory_constructor_test.dart b/pkg/analyzer/test/src/diagnostics/field_initializer_factory_constructor_test.dart
index 948f5568a34..5eb1438bcd0 100644
--- a/pkg/analyzer/test/src/diagnostics/field_initializer_factory_constructor_test.dart
+++ b/pkg/analyzer/test/src/diagnostics/field_initializer_factory_constructor_test.dart
@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+import 'package:analyzer/src/diagnostic/diagnostic.dart' as diag;
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../dart/resolution/context_collection_resolution.dart';
@@ -26,20 +27,34 @@ class A {
   }
 
   test_class_fieldFormalParameter_functionTyped() async {
-    // TODO(srawlins): Only report one error. Theoretically change Fasta to
-    // report "Field initializer in factory constructor" as a parse error.
     await resolveTestCodeWithDiagnostics(r'''
 class A {
   int Function()? x;
   factory A(int this.x());
 //          ^^^^^^^^^^^^
 // [diag.fieldInitializerFactoryConstructor] Initializing formal parameters can't be used in factory constructors.
-//                       ^
-// [diag.missingFunctionBody] A function body must be provided.
 }
 ''');
   }
 
+  test_class_fieldFormalParameter_functionTyped_language305() async {
+    await assertErrorsInCode(
+      r'''
+// @dart = 3.5
+class A {
+  int Function()? x;
+  factory A(int this.x());
+}
+''',
+      [
+        // TODO(srawlins): Only report one error. Theoretically change Fasta to
+        // report "Field initializer in factory constructor" as a parse error.
+        error(diag.fieldInitializerFactoryConstructor, 58, 12),
+        error(diag.missingFunctionBody, 71, 1),
+      ],
+    );
+  }
+
   test_enum_fieldFormalParameter() async {
     await resolveTestCodeWithDiagnostics(r'''
 enum E {