Using Mockito s generic any method

Question

I have an interface with a method that expects an array of Foo   public interface IBar     void doStuff Foo   arr       I am mocking this interface using Mockito  and I d like to assert that doStuff   is called  but I don t want to validate what argument are passed -  don t care    How do I write the following code using any    the generic method  instead of anyObject     IBar bar   mock IBar class       verify bar  doStuff  Foo    anyObject

User · Accepted Answer

Since Java 8 you can use the argument-less any method and the type argument will get inferred by the compiler:

verify(bar).doStuff(any());

Explanation

The new thing in Java 8 is that the target type of an expression will be used to infer type parameters of its sub-expressions. Before Java 8 only arguments to methods where used for type parameter inference (most of the time).

In this case the parameter type of doStuff will be the target type for any(), and the return value type of any() will get chosen to match that argument type.

This mechanism was added in Java 8 mainly to be able to compile lambda expressions, but it improves type inferences generally.

Primitive types

This doesn't work with primitive types, unfortunately:

public interface IBar {
    void doPrimitiveStuff(int i);
}

verify(bar).doPrimitiveStuff(any()); // Compiles but throws NullPointerException
verify(bar).doPrimitiveStuff(anyInt()); // This is what you have to do instead

The problem is that the compiler will infer Integer as the return value type of any(). Mockito will not be aware of this (due to type erasure) and return the default value for reference types, which is null. The runtime will try to unbox the return value by calling the intValue method on it before passing it to doStuff, and the exception gets thrown.

User · Answer

You can use Mockito isA   for that   import static org mockito Matchers isA  import static org mockito Mockito verify   verify bar  doStuff isA Foo   class      http   site mockito org mockito docs current org mockito Matchers html isA java lang Class

User · Answer

As I needed to use this feature for my latest project  at one point we updated from 1 10 19   just to keep the users  that are already using the mockito-core version 2 1 0 or greater  up to date  the static methods from the above answers should be taken from ArgumentMatchers class   import static org mockito ArgumentMatchers isA  import static org mockito ArgumentMatchers any    Please keep this in mind if you are planning to keep your Mockito artefacts up to date as possibly starting from version 3  this class may no longer exist   As per 2 1 0 and above  Javadoc of org mockito Matchers states      Use org mockito 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    I have written a little article on mockito wildcards if you re up for further reading

User · Answer

This should work  import static org mockito ArgumentMatchers any  import static org mockito Mockito verify   verify bar  DoStuff any Foo   class

[java] Using Mockito's generic "any()" method

Explanation

Primitive types

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