Mockito: List Matchers with generics

Question

Mockito offers:

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

How to avoid warning if process takes a List<Bar> instead?

Solution 1

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)));

Solution 2

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.

Solution 3

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());

Comments

[MBach]

Matchers.any() is very convenient!

[Kip]

Note: this is deprecated in Mockito 2.* and will be removed in Mockito 3. Deprecated because Java 8 compiler can infer the type now.

[oddmeter]

Matchers is now deprecated, here's the info from mockito "Use ArgumentMatchers. This class is now deprecated in order to avoid a name clash with Hamcrest org.hamcrest.Matchers class. This class will likely be removed in version 3.0." static.javadoc.io/org.mockito/mockito-core/2.7.21/org/mockit‌​o/…

[Jeff Bowman]

@oddmeter Changes made.

[Fernando Fradegrada]

@artbristol do you know if with anySet() should work as same as anyList()? I am in Java 8 and a warning is thrown in Eclipse IDE

[balki]

Better to use anyListOf. Even though anyList works, it emits a warning.

[edufinn]

anyListOf is deprecated, so it is better NOT to use it. Example for Java 8 doesn't work in case of method overload, for example if you have a method accepting 2 different lists: List<DBEntity> and List<DTO> I've solved this problem using ArgumentMatchers with generic: when(adapter.adapt(ArgumentMatchers.<DTO>anyList())).thenCal‌​lRealMethod();

[Sharm]

Works perfectly, Thankyou