Mocking extension function in Kotlin

Question

How to mock Kotlin extension function using Mockito or PowerMock in tests? Since they are resolved statically should they be tested as static method calls or as non static?

Answer 1

I use mockk library.

For extension file write java name, like this:

@file:JvmName(name = "ExtensionUtils")

package myproject.extension

...

And for fast codding I created file with different extension mocks:

object FastMock {

    fun extension() = mockkStatic("myproject.extension.ExtensionUtils")

    fun listExtension() = mockkStatic("myproject.extension.ListExtensionUtils")

}

In test call this:

FastMock.listExtension()
every { itemList.move(from, to) } returns Unit