Is it possible to mock a suspend inline extension function? If so, how?

# mockk

[Joram Visser]

Is it possible to mock a suspend inline extension function? If so, how?

[oleksiyp]

Believe inline is not supported in any way

[Joram Visser]

Does that mean I can not unit test a function like:

suspend inline fun <reified T : Any> MongoCollection<T>.getOneById(id: ObjectId): Either<MongoError, T> {
    val filter = idFilterQuery(id)
    return try {
        val resultEntity = this.find(filter).awaitFirstOrNull()
        when {
            resultEntity != null -> right(resultEntity)
            else -> left(ENTITY_NOT_FOUND)
        }
    } catch (e: Exception) {
        left(ERROR)
    }
}

Does it mean that I can not call the above function from another class/function and reply with a mocked version.
Does it also mean I won’t be able to call this function in a test case and mock the calls that are made within this inline function?

[LeoColman]

Inline functions are replaced in compilation time. It can't be mocked because technically it doesn't exist when you're executing code, because it was inline

[LeoColman]

You'll have to mock the internals of the function, such as mocking what it calls

[Joram Visser]

I guess inlining a function has its trade offs.
I did manage to mock the internal calls of this inline function. Thanks for the help. 👍