Mockito-参数捕获器未捕获且没有交互

Question

I'm working on some old code that does not handle exceptions very well. One test I'm writing, stubs a method that throws an exception, which I need to confirm is the correct exception. The only way to test this exception that I can see, is to capture the argument when it is being logged and compare the strings.

When I run this I get:

Wanted but not invoked: logger.error(Capturing argument)

Actually there were zero interactions with this mock

@Test
public void testRunCipherThrowsException() throws Exception
{
    final Logger logger = mock(Logger.class);
    ArgumentCaptor<Logger> argument = ArgumentCaptor.forClass(Logger.class);

    when(cipher.doSomething(any(byte[].class))).thenThrow(new IllegalBlockSizeException("Bad block size"));
    Mockito.verify(logger).error(argument.capture());

    _task.run();

    assertEquals("The execution failed.  Details: Bad block size", argument.getValue().getName());
}

Here is a snippet from the class I am testing - in debug I am hitting that line of code every time.

try
{

final byte[] result = cipher.doSomething(testData);

catch (final Exception ex)
    {
        _consequtiveFailures++;
        _logger.error("The execution failed.  Details: " + ex.getMessage(), ex);
    }

I've tried to arrange the test a few different ways thinking the verify might not be getting setup correctly. I have also tried a few different ways of setting of the mock Logger object. It is my first time using argument captor, so hopefully I'm just missing something obvious.

Answer 1

final Logger logger = mock(Logger.class);

This is a logger instance you have created locally for your test method; it will therefore not be used by the class you are testing. You need to at least spy() the actual logger instance.

What is more, you verify() after you execute (I guess here that _task.run() executes the code which will trigger the exception); which means that even if you spied on the correct Logger instance, at the time you verify() it, there will be nothing.

So:

• actually mock, or spy, the actual logger used by _task ;
• verify mock/spy interactions ( Mockito.verify() works for both) after you have executed the method.