i find that i need `single` on a `Map` every once ...

# strikt

[Eric]

i find that i need single on a Map every once in a while, like there is for Collection Might be worth dropping in your std assertions

fun <T : Map<K, V>, K, V> Assertion.Builder<T>.single(): Assertion.Builder<Pair<K, V>> =
    assert("has only one entry") {
        if (it.size == 1) pass(it.size) else fail(it.size)
    }.get("single entry %s") { entries.first().toPair() }

[Eric]

or

fun <T : Map<K, V>, K, V> Assertion.Builder<T>.single(): Assertion.Builder<T> =
    assert("has only one entry") {
        if (it.size == 1) pass(it.size) else fail(it.size)
    }

difference in usage:

get { qux }.single().isEqualTo(" asdf " to "1234")

vs

get { qux }.single().hasEntry(" asdf ", "1234")

[Jakub Gwóźdź]

hmmm. would that be enough?

fun <K, V> DescribeableBuilder<Map<K, V>>.single() = hasSize(1).get { toList() }.single()

(I’m trying to figure out potential problems with such approach)

[Jakub Gwóźdź]

(well, probably too noisy in logs)

[Eric]

or

fun <T : Map<K, V>, K, V> Assertion.Builder<T>.single(): Assertion.Builder<Pair<K, V>> = get { toList() }.single()

[Eric]

or maybe single just isn't needed:

get { qux }.isEqualTo(mapOf(" asdf " to "1234"))

[Jakub Gwóźdź]

The first one would be performance hit on maps with thousands of entries. But it was my first approach too, then I added extra hasSize(1) guard 🙂