Mocking

Mocking start with one call, the mockk function. This function takes in a class and returns a fake version of it, where all functions are present but will throw when called.

import io.mockk.mockk
val mockedFile = mockk<File>()

Stub out behaviour

Using every and returns to define behaviour.

Verify that functions were called

Using verify to check that a function was used.

Automatically stub by relaxing

How to change the default mockk result with relaxed.

Spy on existing classes

Using spyk to mix mocks and real classes.

Coroutines and suspend functions

Using coEvery, coVerify, and more to mock coroutines.

Mock constructors in code you don’t own

Advanced mocking with mockkConstructor.

Mock singleton objects and static methods

Advanced static mocking with mockkStatic and mockkObject.

Mock top-level and extension functions

Mocking top-level functions with mockkStatic.

Clear state

(TODO) Clearing the state of a mock.

Create many mocks quickly with annotations

The @MockK and @SpyK shortcuts.

Chain mocks into hierarchies

(TODO) Building a mock with less code using lambdas.

Create more complicated answers for stubs

Using answers when returns just isn’t enough.