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KeySetPresentAssertion

Issue ID KeySetPresentAssertion · Severity Warning · Category Usability · Default on

Flags assertThat(map.keys).contains(k) — checking key presence by materialising the key set. Use Assert<Map<K, V>>.key(k) directly.

Why

assertThat(map.keys).contains(k) produces a generic "expected to contain X" failure on a Set<K>. key(k) is purpose-built for the same intent and gives a message that names the map. It also transforms the subject to the value type, so you can chain further assertions if you want them.

Example

import assertk.assertThat
import assertk.assertions.contains

fun keyExists() {
    val map = mapOf("9A3E6FAC" to "John")
    assertThat(map.keys).contains("9A3E6FAC")
}

import assertk.assertThat
import assertk.assertions.key

fun keyExists() {
    val map = mapOf("9A3E6FAC" to "John")
    assertThat(map).key("9A3E6FAC")
}

Quick fix

Yes — the IDE rewrites the entire assertThat(map.keys).contains(k) expression to assertThat(map).key(k) and adds assertk.assertions.key.

Source

MapAssertionDetector.kt