fun <K, T : Map<out K, *>> Expect<T>.containsKey(key: K): Expect<T> (source)
Expects that the subject of this expectation (a Map) contains the given key.
expect(mapOf(1 to "a")).containsKey(1)
fails {
expect(mapOf(1 to "a")).containsKey(2) // fails because the map does not contain a key that equals 2
}Return
an Expect for the subject of this expectation.