add tests to demonstrate missing generic function subtype logic

pkg/analyzer/test/src/task/strong/checker_test.dart

 // Copyright (c) 2015, 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.
 
 // TODO(jmesserly): this file needs to be refactored, it's a port from
 // package:dev_compiler's tests
 /// General type checking tests
 library test.src.task.strong.checker_test;
 
 import 'package:unittest/unittest.dart';
@@ skipping 229 matching lines @@
         A.c1(p): this.x = /*info:DOWN_CAST_IMPLICIT*/z, this.y = /*info:DYNAMIC_CAST*/p;
 
         A.c2(this.x, this.y);
 
         A.c3(/*severe:INVALID_PARAMETER_DECLARATION*/num this.x, String this.y);
       }
 
       class B extends A {
         B() : super(/*severe:STATIC_TYPE_ERROR*/"hello");
 
-        B.c2(int x, String y) : super.c2(/*severe:STATIC_TYPE_ERROR*/y, 
+        B.c2(int x, String y) : super.c2(/*severe:STATIC_TYPE_ERROR*/y,
                                          /*severe:STATIC_TYPE_ERROR*/x);
 
         B.c3(num x, Object y) : super.c3(x, /*info:DOWN_CAST_IMPLICIT*/y);
       }
 
       void main() {
          A a = new A.c2(/*info:DOWN_CAST_IMPLICIT*/z, /*severe:STATIC_TYPE_ERROR*/z);
          var b = new B.c2(/*severe:STATIC_TYPE_ERROR*/"hello", /*info:DOWN_CAST_IMPLICIT*/obj);
       }
    '''
@@ skipping 1083 matching lines @@
             /*severe:INVALID_METHOD_OVERRIDE*/A m1(A value) {}
             /*severe:INVALID_METHOD_OVERRIDE*/C m2(C value) {}
             /*severe:INVALID_METHOD_OVERRIDE*/A m3(C value) {}
             C m4(A value) {}
             m5(value) {}
             /*severe:INVALID_METHOD_OVERRIDE*/dynamic m6(dynamic value) {}
           }
        '''
   });
 
+  testChecker('generic class method override', {
+    '/main.dart': '''
+          class A {}
+          class B extends A {}
+
+          class Base<T extends B> {
+            T foo() => null;
+          }
+
+          class Derived<S extends A> extends Base<B> {
+            /*severe:INVALID_METHOD_OVERRIDE*/S foo() => null;
+          }
+
+          class Derived2<S extends B> extends Base<B> {
+            S foo() => null;
+          }
+       '''
+  });
+
+  testChecker('generic method override', {
+    '/main.dart': '''
+          class Future<T> {
+            /*=S*/ then/*<S>*/(/*=S*/ onValue(T t)) => null;
+          }
+
+          // These work because they're exactly equal FunctionTypes
+          class DerivedFuture<T> extends Future<T> {
+            /*=S*/ then/*<S>*/(/*=S*/ onValue(T t)) => null;
+          }
+
+          class DerivedFuture2<A> extends Future<A> {
+            /*=B*/ then/*<B>*/(/*=B*/ onValue(A a)) => null;
+          }
+
+          // These don't work but should.
+          class DerivedFuture3<T> extends Future<T> {
+            /*=/*severe:INVALID_METHOD_OVERRIDE should be pass*/S*/ then/*<S>*/(Object onValue(T t)) => null;
+          }
+
+          class DerivedFuture4<A> extends Future<A> {
+            /*=/*severe:INVALID_METHOD_OVERRIDE should be pass*/B*/ then/*<B>*/(Object onValue(A a)) => null;
+          }
+       '''
+  });
+
   testChecker('unary operators', {
     '/main.dart': '''
       class A {
         A operator ~() {}
         A operator +(int x) {}
         A operator -(int x) {}
         A operator -() {}
       }
 
       foo() => new A();
@@ skipping 1062 matching lines @@
 
         baz1() sync* { yield* (/*info:DYNAMIC_CAST*/x); }
         Iterable baz2() sync* { yield* (/*info:DYNAMIC_CAST*/x); }
         Iterable<int> baz3() sync* { yield* (/*warning:DOWN_CAST_COMPOSITE*/x); }
         Iterable<int> baz4() sync* { yield* new Iterable<int>(); }
         Iterable<int> baz5() sync* { yield* (/*info:INFERRED_TYPE_ALLOCATION*/new Iterable()); }
     '''
     });
   });
 }