Mockito - how to verify that a mock was never invoked

Question

I'm looking for a way to verify with Mockito, that there wasn't any interaction with a given mock during a test. It's easy to achieve that for a given method with verification mode never(), but I haven't found a solution for the complete mock yet.

What I actually want to achieve: verify in tests, that nothing get's printed to the console. The general idea with jUnit goes like that:

private PrintStream systemOut;  @Before public void setUp() {     // spy on System.out     systemOut = spy(System.out); }  @After public void tearDown() {     verify(systemOut, never());  // <-- that doesn't work, just shows the intention } 

A PrintStream has tons of methods and I really don't want to verify each and every one with separate verify - and the same for System.err...

So I hope, if there's an easy solution, that I can, given that I have a good test coverage, force the software engineers (and myself) to remove their (my) debug code like System.out.println("Breakpoint#1"); or e.printStacktrace(); prior to committing changes.

Answer 1

Use this :

import static org.mockito.Mockito.verifyZeroInteractions;  // ...  private PrintStream backup = System.out;  @Before public void setUp() {     System.setOut(mock(PrintStream.class)); }  @After public void tearDown() {     verifyZeroInteractions(System.out);     System.setOut(backup); } 

Answer 2

verifyZeroInteractions(systemOut); 

As noted in comments, this doesn't work with a spy.

For a roughly equivalent but more complete answer, see the answer by gontard to this question.