toContainKey

infix fun <K, T : Map<out K, *>> Expect<T>.toContainKey(key: K): Expect<T>(source)

Expects that the subject of this expectation (a Map) contains the given key.

an Expect for the subject of this expectation.

expect(mapOf(1 to "a")) toContainKey 1

fails { // because the map does not contain a key that equals 2
    expect(mapOf(1 to "a")) toContainKey 2
}