How can I check the constructur arguments of a mockk Mock? - kotlin

Question

I have the following code (in Kotlin):
class X {
fun foo() {
val A(1, true, "three")
val b = B()
b.bar(A)
}
}
What I want to to is find out what A has been instantiated with.
My test code looks like so:
// Needed for something else
every { anyConstructed<A>().go() } returns "testString"
// What I'm using to extract A
val barSlot = slot<A>()
verify { anyConstructed<B>().bar(capture(barSlot)) }
val a = barSlot.captured
How can I check what values A has been instantiated with now I've managed to capture the mock that was created when it was constructed (thanks to the every statement)?
Thanks!

Answer 1

You can do it in two ways:
Using slot to capture the parameter:
#Test
fun shouldCheckValuesAtConstruct() {
val a = A(1, true, "s")
val b = mockk<B>()
val aSlot = slot<A>()
every { b.bar(a = capture(aSlot)) } returns Unit
b.bar(a)
val captured = aSlot.captured
assertEquals(1, captured.a)
assertEquals(true, captured.b)
assertEquals("s", captured.s)
}
Or using withArg function and inline assertions
#Test
fun shouldCheckValuesAtConstructInlineAssertion() {
val a = A(1, true, "s")
val b = mockk<B>()
every { b.bar(a) } returns Unit
b.bar(a)
verify {
b.bar(withArg {
assertEquals(1, it.a)
assertEquals(true, it.b)
assertEquals("s", it.s)
})
}
}