mockk kotlin


MockK supports:


To open classes before Android P you can use DexOpener, example


Implementation is based on dexmaker project. With Android P, instrumentation tests may use full power of inline instrumentation, so object mocks, static mocks and mocking of final classes are supported. Before Android P, only subclassing can be employed, so you will need the ‘all-open’ plugin.

Unfortunately, public CIs such as Travis and Circle are not supporting Android P emulation due to the absence of ARM Android P images. Hopefully, this will change soon.

Supported features

Feature Unit tests Instrumentation test
< Android P ≥ Android P
mocking final classes can use DexOpener
pure Kotlin mocking DSL
matchers partial specification
chained calls
matcher expressions
mocking coroutines
capturing lambdas
object mocks
private function mocking
property backing field access
extension function mocking (static mocks)
constructor mocking


All you need to get started is by adding a dependency to MockK library.

Unit tests

testImplementation "io.mockk:mockk:{version}"

Android instrumented tests

androidTestImplementation "io.mockk:mockk-android:{version}"

current version


Check full documentation here