anchor.diff:    test_initializer_methodInvocation_method() async {
       await assertNoErrorsInCode('''
   class A {
  -  int m1() => null;
  -  T m2<T>() => null;
  +  int m1() => 0;
  +  T m2<T>() => throw 0;
   }
   var a = new A();
   var t1 = a.m1();
  
positive.code:   double foo(int x);
  }
  abstract class C implements A, B {
    Null foo/*error: overrideNoCombinedSuperSignature*/(dynamic x);
  }
  ''');
  
negative.code:   }
  
    test_initializer_extractProperty_implicitlyTyped_differentLibraryCycle() async {
      newFile('$testPackageLibPath/a.dart', content: r'''
  class C {
    var f = 0;
  }
  