How to use ConditionalStackTraceFilter class of org.mockito.internal.exceptions.stacktrace package

An interface is a contract. It has no logic to test.

You can use a mocking framework like Mockito to create an instance of the interface without having to manually stub the methods. But it will just stub them in the background.

You have to ask yourself what you want to test? Given that the interface methods have no implementation there is no code to test.

Say I have an interface like so

public interface DoesStuff {
    void doStuff();
}

What is there to test? The only thing I have said is that I want a class that implements DoesStuff to doStuff.

There is a couple options:

1. Cast it
2. Use @Mock annotation

Examples:

Set<String> mySet = (Set<String>) mock(Set.class);

--or--

@Mock
private Set<String> mySet;

@Before
public void doBefore() throws Exception {
    MockitoAnnotations.initMocks(this.getClass()); //this should create mocks for your objects...
}

The sample works if you remove the PowerMock dependencies. The issue is that the versions of Mockito and PowerMock used are incompatible with each other. For PowerMock 2.x you need at least Mockito 2.8.9+. PowerMock provides a compatibility list that shows what version of PowerMock is compatible with what version of Mockito. Fix up the versions to be compatible with each other and your sample will start to work.

The need is simple: to verify that the correct number of invocations were made. There are scenarios in which method calls should not happen, and others in which they should happen more or less than the default.

Consider the following modified version of embarkOnQuest:

public void embarkOnQuest() {
    quest.embark(); 
    quest.embarkAgain(); 
}

And suppose you are testing error cases for quest.embark():

@Test 
public void knightShouldEmbarkOnQuest() { 
    Quest mockQuest = mock(Quest.class); 
    Mockito.doThrow(RuntimeException.class).when(mockQuest).embark();
    ...
}

In this case you want to make sure that quest.embarkAgain is NOT invoked (or is invoked 0 times):

verify(mockQuest, times(0)).embarkAgain(); //or verifyZeroInteractions

Of course this is one other simple example. There are many other examples that could be added:

• A database connector that should cache entries on first fetch, one can make multiple calls and verify that the connection to the database was called just once (per test query)
• A singleton object that does initialization on load (or lazily), one can test that initialization-related calls are made just once.

Your target URI is: /api/foo/11 based on this root: /api/foo and this path variable: /{id}.

When using MockMvc you set path variables (aka URI variables) like so:

delete(uri, uriVars)

More details in the Javadocs.

So, your test should read:

@Test
public void testFooDelete() throws Exception {
    this.mockMvc.perform(MockMvcRequestBuilders
            .delete("/api/foo/{id}", "11")
            .contentType(MediaType.APPLICATION_JSON))
            .accept(MediaType.APPLICATION_JSON))
            .andExpect(status().isOk());
}

Or alternatively:

@Test
public void testFooDelete() throws Exception {
    this.mockMvc.perform(MockMvcRequestBuilders
            .delete("/api/foo/11")
            .contentType(MediaType.APPLICATION_JSON))
            .accept(MediaType.APPLICATION_JSON))
            .andExpect(status().isOk());
}

You need to inject the mock into the class which you are testing. You do not need access to Subscriber. The way mockito and other mocking frameworks help is that you do not need access to objects which you are interacting with. You do however need a way to get mock objects into the class you are testing.

public class WebAdaptor {

    public WebAdaptor(Subscriber subscriber) { /* Added a new constructor */
       this.subscriber = subscriber;
    }

    private Subscriber subscriber;

    public void run() {
        subscriber.init();
    }
}

Now you can verify your interactions on the mock, rather than on the real object.

@Test
public void runShouldInvokeSubscriberInit() {

    // Given
    Subscriber mockSubscriber = mock(Subscriber.class);
    WebAdaptor adaptor = new WebAdaptor(mockSubscriber);  // Use the new constructor

    // When
    adaptor.run();

    // Then
    verify(mockSubscriber).init();
}

If adding the Subscriber to the constructor is not the correct approach, you could also consider using a factory to allow WebAdaptor to instantiate new Subscriber objects from a factory which you control. You could then mock the factory to provider mock Subscribers.

By default, Mockito uses cglib to create dynamic proxies, but for Android this will not work, because cglib generates .class files, not .dex. But starting from version 1.9.5 Mockito offers an extension point that allows replacing the proxy generation engine, so all you need is change this engine and I think Dexmaker is the best variant.

So to make it works you should just add dexmaker-mockito-1.0.jar to your project, and Mockito will use it to generate his proxies.

This could be achieved by PowerMockito framework.

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

@RunWith(PowerMockRunner.class)
@PrepareForTest(SomeClass.class)
public class SomeClassTest {

    private SomeClass someInstance;

    @Before
    public void setUp() throws Exception {

        someInstance = PowerMockito.spy(new SomeClass());
    }

    @Test
    public void sendRequest() throws Exception {

        String json = "JSON";
        String text = "Some text";
        int messageId = 1;

        PowerMockito.doReturn(true).when(someInstance, "isMethod");
        PowerMockito.doReturn(messageId).when(someInstance, "getMessageId", json);

        someInstance.sendRequest(json, text);

        PowerMockito.verifyPrivate(someInstance).invoke("isMethod");
        PowerMockito.verifyPrivate(someInstance).invoke("getMessageId", json);
        PowerMockito.verifyPrivate(someInstance).invoke("sendMessage", messageId, text);
    }

}

I think your results are compatible with the result that would happen if dbCollection is not a Mockito-mock (or your method is static or final). That would mean that a matcher is being used where none can be used; hence the "0 matchers expected, 1 recorded".