How to use nullPassedToVerifyNoMoreInteractions method of org.mockito.internal.exceptions.Reporter class

Try adding servlet-api dependency

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>3.1.0</version>
    <scope>provided</scope>
</dependency>

It is because of Java/Mockito compatibility. For example, if you are using Java 11 with Mockito 2.17.0, it will throw the same error (Upgrading to Mockito 2.22.0 or later will solve it). Aside from digging into their release artifact on Github, I am yet to see a comprehensive document that spells out the compatibility matrix. Here is a helpful compatibility Matrix (based on quick test)

• Mockito * - 2.17.0 => Java 8

(footnote: * - dont know how far back)

• Mockito 2.18.0 - 3.2.4 => Java 11

If isSkipped() is not a final method, this problem probably indicates that you try to stub a method while stubbing of another method is in progress. It's not supported because Mockito relies on order of method invocations (when(), etc) in its stubbing API.

I guess you have something like this in your test method:

when(...).thenReturn(getSkippedBuild());

If so, you need to rewrite it as follows:

DynamicBuild build = getSkippedBuild();
when(...).thenReturn(build);

For the future I would recommend Eran Harel's answer (refactoring moving new to factory that can be mocked). But if you don't want to change the original source code, use very handy and unique feature: spies. From the documentation:

You can create spies of real objects. When you use the spy then the real methods are called (unless a method was stubbed).

Real spies should be used carefully and occasionally, for example when dealing with legacy code.

In your case you should write:

TestedClass tc = spy(new TestedClass());
LoginContext lcMock = mock(LoginContext.class);
when(tc.login(anyString(), anyString())).thenReturn(lcMock);

The mocks that Mockito creates are generated class files; however, Mockito is designed for use in a JVM, so out of the box it generates .class files using cglib. Android Instrumentation test cases run on devices or emulators, so they need Dalvik .dex files.

You'll need to ensure you're including DexMaker on your classpath. The dexmaker-mockito Maven project seems to be right, though it depends on Mockito 1.10.5, which is a few versions behind at this point.

As a side note, unless you use the Android Testing Support Library, you will need to use JUnit3 semantics. You will not be able to use @Rule fields or custom test runners; you will also need to override setUp and tearDown (as opposed to @Before and @After annotations) and name your tests as testFooBar (as opposed to @Test annotations).

After doing a bit more research, it seems that PowerMockito.spy() and PowerMockito.doReturn() are what is required here:

package com.richashworth.powermockexample;

import org.junit.Before;
import org.junit.BeforeClass;
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;

import java.util.ArrayList;
import java.util.List;

import static org.junit.Assert.assertEquals;


@RunWith(PowerMockRunner.class)
@PrepareForTest({DataProvider.class})
public class ResultsWriterTest {

    private static List<String> mockData = new ArrayList<String>();
    private ResultsWriter resultsWriter;

    @BeforeClass
    public static void setUpOnce() {
        final String firstLine = "Line 1";
        final String secondLine = "Line 2";
        mockData.add(firstLine);
        mockData.add(secondLine);
    }

    @Before
    public void setUp() {
        resultsWriter = new ResultsWriter();
    }

    @Test
    public void testGetDataAsString() throws Exception {
        PowerMockito.spy(DataProvider.class);
        PowerMockito.doReturn(mockData).when(DataProvider.class, "readFile");

        final String expectedData = "Line 1\nLine 2\n";
        final String returnedString = resultsWriter.getDataAsString();

        assertEquals(expectedData, returnedString);
    }

}

For further details and the complete code listing, check out my blog post here: https://richashworth.com/post/turbocharge-your-mocking-framework-with-powermock/

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).

Since Mockito 1.9.5+ and Java 8+

You can use a lambda expression, like:

when(myMock.myFunction(anyString())).thenAnswer(i -> i.getArguments()[0]);

Where i is an instance of InvocationOnMock.

For older versions

You can create an Answer in Mockito. Let's assume, we have an interface named MyInterface with a method myFunction.

public interface MyInterface {
    public String myFunction(String abc);
}

Here is the test method with a Mockito answer:

public void testMyFunction() throws Exception {
    MyInterface mock = mock(MyInterface.class);
    when(mock.myFunction(anyString())).thenAnswer(new Answer<String>() {
    @Override
    public String answer(InvocationOnMock invocation) throws Throwable {
        Object[] args = invocation.getArguments();
        return (String) args[0];
    }
    });

    assertEquals("someString",mock.myFunction("someString"));
    assertEquals("anotherString",mock.myFunction("anotherString"));
}

I've had good success using Mockito.

When I tried learning about JMock and EasyMock, I found the learning curve to be a bit steep (though maybe that's just me).

I like Mockito because of its simple and clean syntax that I was able to grasp pretty quickly. The minimal syntax is designed to support the common cases very well, although the few times I needed to do something more complicated I found what I wanted was supported and easy to grasp.

Here's an (abridged) example from the Mockito homepage:

import static org.mockito.Mockito.*;

List mockedList = mock(List.class);
mockedList.clear();
verify(mockedList).clear();

It doesn't get much simpler than that.

The only major downside I can think of is that it won't mock static methods.