Type returnType = method.getGenericReturnType();
    Type paramType = getOnlyParameterType();
    TestSubtype spec = method.getAnnotation(TestSubtype.class);
    assertWithMessage("%s is subtype of %s", paramType, returnType)
        .that(TypeToken.of(paramType).isSubtypeOf(returnType))
        .isTrue();
    assertWithMessage("%s is supertype of %s", returnType, paramType)
        .that(TypeToken.of(returnType).isSupertypeOf(paramType))

    Type returnType = method.getGenericReturnType();
    Type paramType = getOnlyParameterType();
    TestSubtype spec = method.getAnnotation(TestSubtype.class);
    assertWithMessage("%s is subtype of %s", paramType, returnType)
        .that(TypeToken.of(paramType).isSubtypeOf(returnType))
        .isTrue();
    assertWithMessage("%s is supertype of %s", returnType, paramType)
        .that(TypeToken.of(returnType).isSupertypeOf(paramType))

        method.returnType = new TypeMetaData('ReturnType')
        method.addParameter('param1', new TypeMetaData('ParamType'))
        method.addParameter('param2', new TypeMetaData('ParamType2'))

        expect:
        method.signature == 'ReturnType method(ParamType param1, ParamType2 param2)'
        method.overrideSignature == 'method(ParamType, ParamType2)'
    }

    def formatsOverrideSignatureUsingRawParameterTypes() {

    FreshValueGenerator paramValues = new FreshValueGenerator();
    List<@Nullable Object> passedArgs = Lists.newArrayList();
    for (Class<?> paramType : method.getParameterTypes()) {
      passedArgs.add(paramValues.generateFresh(paramType));
    }
    return passedArgs.toArray();
  }

  /** Tests a single interaction against a method. */

    FreshValueGenerator paramValues = new FreshValueGenerator();
    List<@Nullable Object> passedArgs = Lists.newArrayList();
    for (Class<?> paramType : method.getParameterTypes()) {
      passedArgs.add(paramValues.generateFresh(paramType));
    }
    return passedArgs.toArray();
  }

  /** Tests a single interaction against a method. */