Mockito: List Matchers with generics

Question

For Java 8 and above, it's easy:

when(mock.process(Matchers.anyList()));

For Java 7 and below, the compiler needs a bit of help. Use anyListOf(Class<T> clazz):

when(mock.process(Matchers.anyListOf(Bar.class)));

In addition to anyListOf above, you can always specify generics explicitly using this syntax:

when(mock.process(Matchers.<List<Bar>>any(List.class)));

Java 8 newly allows type inference based on parameters, so if you're using Java 8, this may work as well:

when(mock.process(Matchers.any()));

Remember that neither any() nor anyList() will apply any checks, including type or null checks. In Mockito 2.x, any(Foo.class) was changed to mean "any instanceof Foo", but any() still means "any value including null".

NOTE: The above has switched to ArgumentMatchers in newer versions of Mockito, to avoid a name collision with org.hamcrest.Matchers. Older versions of Mockito will need to keep using org.mockito.Matchers as above.

Before Java 8 (versions 7 or 6) I use the new method ArgumentMatchers.anyList:

import static org.mockito.Mockito.*;
import org.mockito.ArgumentMatchers;

verify(mock, atLeastOnce()).process(ArgumentMatchers.<Bar>anyList());