How to mock an array containing objects using mockito?

Question

In my Mockito unit test I am trying to mock an array containing instances of the object Message. To do this I try to mock it like normal objects so like:

private var messagesMock = mock(Array<Message>::class.java)

This gives the following error/exception:

org.mockito.exceptions.base.MockitoException: 
Cannot mock/spy class [Lrobot.fsrt.robotguest.common.data.Message;
Mockito cannot mock/spy because :
 - VM does not not support modification of given type

How to mock an array the right way using Mockito?

Also note: your question isn't really clear. Is Message a variable, or is it a generic type. Do you want to have ONE array with the object Message within it, or do you want to create some generic Array<Message> instance? So a real minimal reproducible example with additional context would definitely help here. — GhostCat
– GhostCat, Commented May 20, 2019 at 6:42

GhostCat · Accepted Answer · 2019-05-20 06:40:33Z

3

A distinct non-answer: you (almost) never mock objects that represent containers!

An array is just that: a container.

You create the container with the size you need, and then you put your mocked objects into that ordinary container, and make sure that container with your prepared content gets used by your production code.

It is as simple as that: you don't mock arrays, or lists, or maps: you create them as is, and manipulate their content!

answered May 20, 2019 at 6:40

GhostCat

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2 Comments

Pedro Paulo Amorim Over a year ago

What if I want to test the iterator?

GhostCat Over a year ago

What do you mean? Testing your own implementation of some interface like iterable is a different story.

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