fix #25183, add support to ErrorVerifier for generic methods

pkg/analyzer/test/generated/resolver_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // 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.
 
 library engine.resolver_test;
 
 import 'dart:collection';
 
 import 'package:analyzer/src/context/context.dart';
 import 'package:analyzer/src/generated/ast.dart';
@@ skipping 12954 matching lines @@
   g/*<S>*/(/*=S*/ x) => f;
   return null;
 }
 ''');
     SimpleIdentifier g = _findIdentifier('f');
     expect(g.staticType.toString(), '<S>(S) → S');
     SimpleIdentifier f = _findIdentifier('g');
     expect(f.staticType.toString(), '<S>(S) → dynamic');
   }
 
+  void test_genericMethod_override() {
+    _resolveTestUnit(r'''
+class C {
+  /*=T*/ f/*<T>*/(/*=T*/ x) => null;
+}
+class D extends C {
+  /*=T*/ f/*<T>*/(/*=T*/ x) => null; // from D
+}
+''');
+    SimpleIdentifier f =
+        _findIdentifier('f/*<T>*/(/*=T*/ x) => null; // from D');
+    MethodElementImpl e = f.staticElement;
+    expect(e.typeParameters.toString(), '[T]');
+    expect(e.type.boundTypeParameters.toString(), '[T]');
+    expect(e.type.toString(), '<T>(T) → T');
+
+    FunctionType ft = e.type.instantiate([typeProvider.stringType]);
+    expect(ft.toString(), '(String) → String');
+  }
+
+  void test_genericMethod_override_bounds() {
+    _resolveTestUnit(r'''
+class A {}
+class B extends A {}
+class C {
+  /*=T*/ f/*<T extends B>*/(/*=T*/ x) => null;
+}
+class D extends C {
+  /*=T*/ f/*<T extends A>*/(/*=T*/ x) => null;
+}
+''');
+  }
+
+  void test_genericMethod_override_invalidReturnType() {
+    Source source = addSource(r'''
+class C {
+  Iterable/*<T>*/ f/*<T>*/(/*=T*/ x) => null;
+}
+class D extends C {
+  String f/*<S>*/(/*=S*/ x) => null;
+}''');
+    // TODO(jmesserly): we can't use assertErrors because STRONG_MODE_* errors
+    // from CodeChecker don't have working equality.
+    List<AnalysisError> errors = analysisContext2.computeErrors(source);
+    expect(errors.map((e) => e.errorCode.name), [
+      'INVALID_METHOD_OVERRIDE_RETURN_TYPE',
+      'STRONG_MODE_INVALID_METHOD_OVERRIDE'
+    ]);
+    expect(errors[0].message, contains('Iterable<S>'),
+        reason: 'errors should be in terms of the type parameters '
+            'at the error location');
+    verify([source]);
+  }
+
+  void test_genericMethod_override_invalidTypeParamBounds() {
+    Source source = addSource(r'''
+class A {}
+class B extends A {}
+class C {
+  /*=T*/ f/*<T extends A>*/(/*=T*/ x) => null;
+}
+class D extends C {
+  /*=T*/ f/*<T extends B>*/(/*=T*/ x) => null;
+}''');
+    // TODO(jmesserly): this is modified code from assertErrors, which we can't
+    // use directly because STRONG_MODE_* errors don't have working equality.
+    List<AnalysisError> errors = analysisContext2.computeErrors(source);
+    expect(errors.map((e) => e.errorCode.name), [
+      'STRONG_MODE_INVALID_METHOD_OVERRIDE',
+      'INVALID_METHOD_OVERRIDE_TYPE_PARAMETER_BOUND'
+    ]);
+    verify([source]);
+  }
+
+  void test_genericMethod_override_invalidTypeParamCount() {
+    Source source = addSource(r'''
+class C {
+  /*=T*/ f/*<T>*/(/*=T*/ x) => null;
+}
+class D extends C {
+  /*=S*/ f/*<T, S>*/(/*=T*/ x) => null;
+}''');
+    // TODO(jmesserly): we can't use assertErrors because STRONG_MODE_* errors
+    // from CodeChecker don't have working equality.
+    List<AnalysisError> errors = analysisContext2.computeErrors(source);
+    expect(errors.map((e) => e.errorCode.name), [
+      'STRONG_MODE_INVALID_METHOD_OVERRIDE',
+      'INVALID_METHOD_OVERRIDE_TYPE_PARAMETERS'
+    ]);
+    verify([source]);
+  }
+
   void test_pseudoGeneric_max_doubleDouble() {
     String code = r'''
 import 'dart:math';
 main() {
   var foo = max(1.0, 2.0);
 }
 ''';
     _resolveTestUnit(code);
 
     SimpleIdentifier identifier = _findIdentifier('foo');
@@ skipping 2972 matching lines @@
 
   void _resolveTestUnit(String code) {
     testCode = code;
     testSource = addSource(testCode);
     LibraryElement library = resolve2(testSource);
     assertNoErrors(testSource);
     verify([testSource]);
     testUnit = resolveCompilationUnit(testSource, library);
   }
 }