How to use shouldFailVerification method of org.mockitousage.verification.BasicVerificationInOrderTest class

Also, a slightly more terse way to get around this is to use the do syntax instead of when.

doReturn(User.class).when(methodParameter).getParameterType();

You can not force a subclass to override a method. You can only force it to implement a method by making it abstract.

So if you can not make myMotherClass abstract you can only introduce another superclass that extends myMotherClass and delegates to the method that must be implemented:

public abstract class EnforceImplementation extends myMotherClass {

        public final void myMethod(){
             implementMyMethod();
        }

        public abstract void implementMyMethod();
}

EDIT

I found another interessting way of solving the problem in the hemcrest api that is e.g. used by mockito.

public interface Matcher<T> extends SelfDescribing {

    /**
     * Evaluates the matcher for argument <var>item</var>.
     * <p/>
     * This method matches against Object, instead of the generic type T. This is
     * because the caller of the Matcher does not know at runtime what the type is
     * (because of type erasure with Java generics). It is down to the implementations
     * to check the correct type. 
     *
     * @param item the object against which the matcher is evaluated.
     * @return <code>true</code> if <var>item</var> matches, otherwise <code>false</code>.
     *
     * @see BaseMatcher
     */
    boolean matches(Object item);

    /**
     * This method simply acts a friendly reminder not to implement Matcher directly and
     * instead extend BaseMatcher. It's easy to ignore JavaDoc, but a bit harder to ignore
     * compile errors .
     *
     * @see Matcher for reasons why.
     * @see BaseMatcher
     */
    void _dont_implement_Matcher___instead_extend_BaseMatcher_();
}

The interface specifies a method _dont_implement_Matcher___instead_extend_BaseMatcher_. Of course it does not prevent others from implementing the Matcher interface, but it guides the developer in the right direction.

And the BaseMatcher class implements the _dont_implement_Matcher___instead_extend_BaseMatcher_ method as final

public final void _dont_implement_Matcher___instead_extend_BaseMatcher_() {
    // See Matcher interface for an explanation of this method.
}

Finally I think that this is a design problem, because the BaseMatcher obviouosly implements logic that every Matcher should implement. Thus it would have been better to make the Matcher an abstract class and use a template method.

But I guess they did it because it was the best compromise between bytecode compatibility and new features.

There is a type-safe way: use ArgumentMatchers.any() and qualify it with the type:

ArgumentMatchers.<AsyncCallback<ResponseX>>any()

Mockito based solution where code uses plain Instant.now()

import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.mockito.MockedStatic;

import java.time.Clock;
import java.time.Instant;

import static org.assertj.core.api.Assertions.assertThat;
import static org.mockito.Mockito.mockStatic;
import static org.mockito.Mockito.spy;
import static org.mockito.Mockito.when;

public class MockInstantTest {

  private MockedStatic<Clock> clockMock;

  @BeforeEach
  public void setup() {
    mockInstant(1640000000); // set desired return value 2021-12-20T11:33:20Z
  }

  @AfterEach
  public void destroy() {
    clockMock.close();
  }

  private void mockInstant(long expected) {
    Clock spyClock = spy(Clock.class);
    clockMock = mockStatic(Clock.class);
    clockMock.when(Clock::systemUTC).thenReturn(spyClock);
    when(spyClock.instant()).thenReturn(Instant.ofEpochSecond(expected));
  }

  @Test
  void testWithMockedIstant() {
    // invoking Instant.now() will always return the same value
    assertThat(Instant.now().toString()).isEqualTo("2021-12-20T11:33:20Z");
  }
}

Solution Explained

Solution relays on the fact that Instant.now() invokes Clock.systemUTC().instant()

• Clock is abstract so we spy for non static methods
• clock.instant() is mocked to return the desired value
• Clock.systemUTC() is static so we need mockStatic
• using @Before/@After is required to close MockedStatic (alternatively you can use try(MockedStatic<Clock> clockMock = mockStatic(Clock.class)) {...})

I've recently adopted a project that uses JMockit and I think the quality of the code has certainly suffered as a result of the library's ability to mock out static and private methods.

The tests are very brittle because implementation details contained in private methods are being tested (so if I change how the class does something it can break tests, even if what the class does has not been affected).

The code is also littered with calls to static methods - if the developers had not had the ability to mock these out then I think they would have made more effort to de-couple things a little better.

I think you do need to cast it, but it shouldn't be too bad:

Foo<Bar> mockFoo = (Foo<Bar>) mock(Foo.class);
when(mockFoo.getValue()).thenReturn(new Bar());

I had this problem today. It is caused by calls to the mock to set up stubbing actually consuming the stubbing already in place.

In this example, change the first line to

when(mock.call(anyString())).thenReturn("","",string1,string2)

This will give you two blank responses when you set up your other mock returns, leaving string1 as the first useful return value.

Try also the doReturn alternative which I think may not have these issues:

doReturn(string1,string2).when(mock).call(anyString());

This uses the stub differently during setup.

So I did some more research on this. Here's the function I was playing with, based on the OP's question:

    Function<String, String> function = mock(Function.class);
    when(function.apply(anyString())).thenReturn("A","B","C");
    when(function.apply("Jim")).thenReturn("Jim");
    when(function.apply("Bob")).thenReturn("Bob");

    assertThat(function.apply("Jim")).isEqualTo("Jim");
    assertThat(function.apply("Bob")).isEqualTo("Bob");
    assertThat(function.apply("")).isEqualTo("A");
    assertThat(function.apply("")).isEqualTo("B");
    assertThat(function.apply("")).isEqualTo("C");
    assertThat(function.apply("")).isEqualTo("C");

The above fails at isEqualTo("A") because the two calls to set up the mocks for Jim and Bob consume return values from the list provided to anyString().

You might be tempted to reorder the when clauses, but that fails, because the anyString() supersedes the special cases, so that fails too.

The following version of the above DOES work as expected:

    when(function.apply(anyString())).thenReturn("A","B","C");

    doReturn("Jim")
        .when(function)
        .apply("Jim");
    doReturn("Bob")
        .when(function)
        .apply("Bob");

    assertThat(function.apply("Jim")).isEqualTo("Jim");
    assertThat(function.apply("Bob")).isEqualTo("Bob");
    assertThat(function.apply("")).isEqualTo("A");
    assertThat(function.apply("")).isEqualTo("B");
    assertThat(function.apply("")).isEqualTo("C");
    assertThat(function.apply("")).isEqualTo("C");

This is because the doReturn technique, which is intended for modifying pre-existing mocks in flight, doesn't actually involve calling the method on the mock to set up the mocking.

You could use doReturn for all setup, rather than mixing between when...thenReturn and doReturn..when..function(). As it happens, that's a bit uglier:

    doReturn("A").doReturn("B").doReturn("C")
        .when(function)
        .apply(anyString());

There's no convenient varargs function to let you specify multiple returns in sequence. The above has been tested and does work, though.

You don't normally set properties on your mocked objects; instead, you do some specific thing when it's invoked.

when(slingHttpRequest.getAttribute("search")).thenReturn(someObject);

I think the answer is no -- perhaps you could pull it off with some intense reflection wrangling, but if so I don't think it would be worth your time.

But I think (without seeing your method), you can probably still get full coverage on your method:

• If your method takes any action after catching the exception, assert or verify that those actions happened.
  
  
• If no action happens after catching the exception, assert or verify that whatever actions were supposed to happen but were cut off by the exception, didn't happen.
  
  
• Finally, (again, not seeing your method I don't know exactly what you're dealing with) if your method is void, and nothing happens after catching the exception, and the last line of logic is what can throw the exception, then consider making your method return a boolean, have it return false if the exception is caught and true otherwise. Then in your test, make a scenario that should cause the exception to be thrown and caught, and test that the method returns false.