检查单元测试是否委派了所有方法

Question

假设我有以下课程

public abstract class Foo{

  public int bar(){
    //implementation
  }
  public abstract int bar2();
}

和一个基类,以便更容易为此类编写装饰器

public class FooWrapper{
  private final Foo delegate;

  protected FooWrapper( Foo delegate ){
    this.delegate = delegate;
  }
  @Override
  public int bar(){
    return delegate.bar()
  }
  @Override
  public int bar2(){
    return delegate.bar2();
  }
}

该类FooWrapper允许您编写装饰器,Foo只覆盖您需要的方法.

现在我想编写一个测试FooWrapper,检查是否默认委派所有方法.当然我可以写一些类似的东西

@Test
public void barShouldBeDelegated(){
  Foo delegate = Mockito.mock( Foo.class );
  FooWrapper wrapper = new FooWrapper( delegate );
  wrapper.bar();
  Mockito.verify( delegate ).bar();
}

但这需要我在每次添加方法时添加新的测试方法Foo.我希望每次添加一个Foo我忘记覆盖和委托的方法时,测试都会失败FooWrapper.

我试图使用反射,允许我调用每个方法,但我不知道如何检查该方法是否实际委派.请参阅以下代码片段,了解我的想法:

  @Test
  public void testAllMethodsAreDelegated() throws Exception{
    Foo delegate = mock(Foo.class);
    FooWrapper wrapper = new FooWrapper(delegate);

    Class<?> clazz = wrapper.getClass();
    Method[] methods = clazz.getDeclaredMethods();

    for (Method method : methods) {
      Class<?>[] parameterTypes = method.getParameterTypes();
      Object[] arguments = new Object[parameterTypes.length];
      for (int j = 0; j < arguments.length; j++) {
        arguments[j] = Mockito.mock(parameterTypes[j]);
      }
      method.invoke(wrapper, arguments);

      // ?? how to verify whether the delegate is called
      // Mockito.verify( delegate ).??? does not work 
      // as I cannot specify the method by name
      }
    }
  }

是否有可能编写这样的测试.请注意,我可以使用的唯一模拟框架是Mockito.

Answer 1

这段代码似乎可以解决问题.如果我向Foo添加一个方法并且不在Fo​​oWrapper中包含它,则测试失败.

    FooWrapper wrapper = new FooWrapper(delegate);
    Foo delegate = Mockito.mock(Foo.class);

    // For each method in the Foo class...
    for (Method fooMethod : Foo.class.getDeclaredMethods()) {
        boolean methodCalled = false;

        // Find matching method in wrapper class and call it
        for (Method wrapperMethod : FooWrapper.class.getDeclaredMethods()) {
            if (fooMethod.getName().equals(wrapperMethod.getName())) {

                // Get parameters for method
                Class<?>[] parameterTypes = wrapperMethod.getParameterTypes();
                Object[] arguments = new Object[parameterTypes.length];
                for (int j = 0; j < arguments.length; j++) {
                    arguments[j] = Mockito.mock(parameterTypes[j]);
                }

                // Invoke wrapper method
                wrapperMethod.invoke(wrapper, arguments);

                // Ensure method was called on delegate exactly once with the correct arguments
                fooMethod.invoke(Mockito.verify(delegate, Mockito.times(1)), arguments);

                // Set flag to indicate that this foo method is wrapped properly.
                methodCalled = true;
            }
        }

        assertTrue("Foo method '" + fooMethod.getName() + "' has not been wrapped correctly in Foo wrapper", methodCalled);
    }

这里的代码中缺少的关键是

fooMethod.invoke(Mockito.verify(delegate, Mockito.times(1)), arguments);

它可能看起来有点奇怪,但这是有效的,因为它以Mockito所期望的相同顺序调用事物:首先Mockito.verify(delegate)调用(在内部启动Mockito验证),然后调用该方法.类似的非反射调用看起来像Mockito.verify(delegate).foo().使用此"原因"来帮助调整代码以适应不同的用例,而不会破坏测试的验证方式.

需要注意的是,我会在每个循环的开头添加一个检查,迭代getDeclaredMethods()的结果.此方法返回所有方法,无论它们是公共的,私有的,受保护的等.尝试访问不可访问的方法会引发异常.您可以使用Method.isAccessible()来检查这一点.