Our system under test will be a TaxTransferer class that will transfer tax for a non-null person as follows:

public class TaxTransferer {

    private final TaxService taxService;

    public TaxTransferer(TaxService taxService) {
        this.taxService = taxService;
    }

    public void transferTaxFor(Person person) {
        if (person == null) {
            return;
        }
        taxService.transferTaxFor(person);
    }

}

To verify whether the mock's method was not invoked, call Mockito.verify(mock, VerificationMode.never()).methodToVerify(...).

Let's check the JUnit test that verifies whether the web service's method has been called at most twice (see Chapter 1, Getting Started with Mockito, for the TestNG configuration):

@RunWith(MockitoJUnitRunner.class)
public class TaxTransfererTest {

    @Mock TaxService taxService;

    @InjectMocks TaxTransferer systemUnderTest;

    @Test
    public void should_not_call_web_service_method_if_person_is_null() {
        // when
        systemUnderTest.transferTaxFor(null);

        // then
        verify(taxService, never()).transferTaxFor(any(Person.class));
    }

}

Since the never() verification works in the same way as the times(0) verification, please refer to the How it works... section of the Verifying the method invocation count with times() recipe for more details.

You can use the Mockito.verifyZeroInteractions(...) method to specify that you do not wish interactions to take place with a mock.

However, it will involve all the existing calls on the mock (even those from the setup phase of your test). So, we could rewrite the aforementioned test in another, less user friendly and readable way; for example, for JUnit, you can use the following code:

@RunWith(MockitoJUnitRunner.class)
public class TaxTransfererTest {

    @Mock TaxService taxService;

    @InjectMocks TaxTransferer systemUnderTest;

    @Test
    public void should_not_interact_with_web_service_in_any_way_if_person_is_null() {
        // when
        systemUnderTest.transferTaxFor(null);

        // then
        verifyZeroInteractions(taxService);
    }
}

You can call either the verifyZeroInteractions(...) or verifyNoMoreInteractions(...) method and get the same result since both do the same task (they call the same methods under the hood).