How to use shouldMatchWhenFieldValuesEqual method of org.mockitousage.matchers.CustomMatcherDoesYieldCCETest class

With Mockito you can verify that a method was called:

verify(mockOne).add("one");

or that it was never called (never() is more readable alias for times(0)):

verify(mockOne, never()).remove("two");

Or you can verify that no other method was called:

verify(mockOne).add("one"); // check this one
verifyNoMoreInteractions(mockOne); // and nothing else

For more information see the Mockito documentation.

To directly answer your question, yes, you can mock some methods without mocking others. This is called a partial mock. See the Mockito documentation on partial mocks for more information.

For your example, you can do something like the following, in your test:

Stock stock = mock(Stock.class);
when(stock.getPrice()).thenReturn(100.00);    // Mock implementation
when(stock.getQuantity()).thenReturn(200);    // Mock implementation
when(stock.getValue()).thenCallRealMethod();  // Real implementation

In that case, each method implementation is mocked, unless specify thenCallRealMethod() in the when(..) clause.

There is also a possibility the other way around with spy instead of mock:

Stock stock = spy(Stock.class);
when(stock.getPrice()).thenReturn(100.00);    // Mock implementation
when(stock.getQuantity()).thenReturn(200);    // Mock implementation
// All other method call will use the real implementations

In that case, all method implementation are the real one, except if you have defined a mocked behaviour with when(..).

There is one important pitfall when you use when(Object) with spy like in the previous example. The real method will be called (because stock.getPrice() is evaluated before when(..) at runtime). This can be a problem if your method contains logic that should not be called. You can write the previous example like this:

Stock stock = spy(Stock.class);
doReturn(100.00).when(stock).getPrice();    // Mock implementation
doReturn(200).when(stock).getQuantity();    // Mock implementation
// All other method call will use the real implementations

Another possibility may be to use org.mockito.Mockito.CALLS_REAL_METHODS, such as:

Stock MOCK_STOCK = Mockito.mock( Stock.class, CALLS_REAL_METHODS );

This delegates unstubbed calls to real implementations.

However, with your example, I believe it will still fail, since the implementation of getValue() relies on quantity and price, rather than getQuantity() and getPrice(), which is what you've mocked.

Another possibility is to avoid mocks altogether:

@Test
public void getValueTest() {
    Stock stock = new Stock(100.00, 200);
    double value = stock.getValue();
    assertEquals("Stock value not correct", 100.00*200, value, .00001);
}

A better way to accomplish that would probably be:

when(someService.someMethod(id)).thenThrow(new AccountNotFoundException());

then the compiler should infer the type correctly.

If someService.someMethod(id) has return type void you can do:

doThrow(new AccountNotFoundException()).when(someService).someMethod(id);

Please refer to the official Mockito documentation for examples like this using thenThrow. The documentation is very clear on this point.

You can also check the following StackOverflow question which is very similar (if not an exact duplicate):

How to mock and assert a thrown exception

As Lucas says, JSON is bundled up with the Android SDK, so you are working with a stub.

The current solution is to pull JSON from Maven Central like this:

dependencies {
    ...
    testImplementation 'org.json:json:20210307'
}

You can replace the version 20210307 with the the latest one depending on the Android API. It is not known which version of the maven artefact corresponds exactly/most closely to what ships with Android.

Alternatively, you can download and include the jar:

dependencies {
    ...
    testImplementation files('libs/json.jar')
}

Note that you also need to use Android Studio 1.1 or higher and at least build tools version 22.0.0 or above for this to work.

Related issue: #179461

You should use an argThat wildcard for each of the inputs:

verify(mockService).methodA(argThat((List ids) -> ids.get(0).equals("123"))
          , argThat((int b) -> b < 1);

I would also suggest you use @ArgumentCaptor which is an alternative to argThat and makes that custom matching a bit more clear: javadoc. Especially if you have to use both of the params at the same conditional statement.

I could make your unit test pass by modifying 2 things in your code:

1. Mock mockServerSocket.accept() properly

Up to now, you mock mockServerSocket.accept() too early because mockTestClientSocket has not yet been set so it will return null, you need to set it first so your code should rather be:

mockServerSocket = mock(ServerSocket.class);
// Set it first
mockTestClientSocket = mock(Socket.class);

try {
    // Then mock it
    when(mockServerSocket.accept()).thenReturn(mockTestClientSocket);
} catch (IOException e) {
    fail(e.getMessage());
}
...

2. Synchronize your threads properly

As you launch a dedicated thread to manage your client socket, you need to synchronize your threads in order to make sure that your message will be ready to be read.

To do this you could:

1. Simplify your code by calling reader.readLine() but it is a blocking approach since your current thread will wait as long as it is needed for the other thread to write the line (the message here).

The code could be:

BufferedReader reader = ...

String receivedMessage = reader.readLine();
assertEquals("Hello, world!", receivedMessage);
mockTestClientSocket.close();
connection.closeSocket();

2. Set a value for TIMEOUT_TIME big enough even exaggeratedly big to make sure that the other thread will be ready, so for example as it is a value in nanoseconds, you could set it to 30 seconds so to 30_000_000_000L. If you don't set a value big enough, your test could be unstable in slow and/or overloaded and/or shared system such as server used for continuous integration.

ServletRequest, ServletResponse and FilterChain are all interfaces, so you can easily create test stubs for them, either by hand or using a mocking framework.

Make the mock objects configurable so that you can prepare a canned response to getRequestURI() and so that you can query the ServletResponse to assert that sendRedirect has been invoked.

Inject a mock ModeService.

Invoke doFilter passing the mock ServletRequest, ServletResponse and FilterChain as its parameters.

@Test
public void testSomethingAboutDoFilter() {
    MyFilter filterUnderTest = new MyFilter();
    filterUnderTest.setModeService(new MockModeService(ModeService.ONLINE));
    MockFilterChain mockChain = new MockFilterChain();
    MockServletRequest req = new MockServletRequest("/maintenance.jsp");
    MockServletResponse rsp = new MockServletResponse();

    filterUnderTest.doFilter(req, rsp, mockChain);

    assertEquals("/maintenance.jsp",rsp.getLastRedirect());
}

In practice you'll want to move the setup into an @Before setUp() method, and write more @Test methods to cover every possible execution path.

... and you'd probably use a mocking framework like JMock or Mockito to create mocks, rather than the hypothetical MockModeService etc. I've used here.

This is a unit testing approach, as opposed to an integration test. You are only exercising the unit under test (and the test code).

You could capture the value, e.g.

final ArgumentCaptor<Double> captor = ArgumentCaptor.forClass(Double.class)
...
verify(myManager).method1(captor.capture());

Then assert:

assertEquals(expected, captor.getValue(), delta)

Or, perhaps, use an argument matcher which does the assertion:

verify(myManager).method1(doubleThat(new ArgumentMatcher<Double>() 
{
    @Override 
    public boolean matches(final Object actual)
    {
        return Math.abs(expected - (Double) actual) <= delta;
    }
}));

Update:

Instead of using either of the methods above, you could use AdditionalMatchers.eq(double, double) instead, e.g.:

verify(myManager).method1(AdditionalMatchers.eq(expected, delta));

Although use AdditonalMatchers matchers wisely, as per the documentation:

AdditionalMatchers provides rarely used matchers, kept only for somewhat compatibility with EasyMock. Use additional matchers very judiciously because they may impact readability of a test. It is recommended to use matchers from Matchers and keep stubbing and verification simple.

Take a look at the Mockito API docs. As the linked document mentions (Point # 12) you can use any of the doThrow(),doAnswer(),doNothing(),doReturn() family of methods from Mockito framework to mock void methods.

For example,

Mockito.doThrow(new Exception()).when(instance).methodName();

or if you want to combine it with follow-up behavior,

Mockito.doThrow(new Exception()).doNothing().when(instance).methodName();

Presuming that you are looking at mocking the setter setState(String s) in the class World below is the code uses doAnswer method to mock the setState.

World mockWorld = mock(World.class); 
doAnswer(new Answer<Void>() {
    public Void answer(InvocationOnMock invocation) {
      Object[] args = invocation.getArguments();
      System.out.println("called with arguments: " + Arrays.toString(args));
      return null;
    }
}).when(mockWorld).setState(anyString());