shouldExist-more-info (#62)

kotest · Apr 26, 2024 · a47ad80 · a47ad80
1 parent b612160
commit a47ad80
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Showing 2 changed files with 16 additions and 5 deletions.
diff --git a/...s/kotest-assertions-core/src/commonMain/kotlin/io/kotest/matchers/collections/matchers.kt b/...s/kotest-assertions-core/src/commonMain/kotlin/io/kotest/matchers/collections/matchers.kt
@@ -27,11 +27,16 @@ infix fun <T> Iterable<T>.shouldExist(p: (T) -> Boolean) = toList().shouldExist(
 infix fun <T> Array<T>.shouldExist(p: (T) -> Boolean) = asList().shouldExist(p)
 infix fun <T> Collection<T>.shouldExist(p: (T) -> Boolean) = this should exist(p)
 fun <T> exist(p: (T) -> Boolean) = object : Matcher<Collection<T>> {
-   override fun test(value: Collection<T>) = MatcherResult(
-      value.any { p(it) },
-      { "Collection ${value.print().value} should contain an element that matches the predicate $p" },
-      { "Collection ${value.print().value} should not contain an element that matches the predicate $p" }
-   )
+   override fun test(value: Collection<T>): MatcherResult {
+      val matchingElementsIndexes = value.mapIndexedNotNull { index, element ->
+         if(p(element)) index else null
+      }
+      return MatcherResult(
+         matchingElementsIndexes.isNotEmpty(),
+         { "Collection ${value.print().value} should contain an element that matches the predicate $p" },
+         { "Collection ${value.print().value} should not contain an element that matches the predicate $p, but elements with the following indexes matched: ${matchingElementsIndexes.print().value}" }
+      )
+   }
 }
 
 fun <T> Iterable<T>.shouldMatchInOrder(vararg assertions: (T) -> Unit) = toList().shouldMatchInOrder(assertions.toList())

diff --git a/...ore/src/jvmTest/kotlin/com/sksamuel/kotest/matchers/collections/CollectionMatchersTest.kt b/...ore/src/jvmTest/kotlin/com/sksamuel/kotest/matchers/collections/CollectionMatchersTest.kt
@@ -18,6 +18,7 @@ import io.kotest.matchers.collections.containDuplicates
 import io.kotest.matchers.collections.containNoNulls
 import io.kotest.matchers.collections.containNull
 import io.kotest.matchers.collections.containOnlyNulls
+import io.kotest.matchers.collections.exist
 import io.kotest.matchers.collections.existInOrder
 import io.kotest.matchers.collections.haveElementAt
 import io.kotest.matchers.collections.haveSize
@@ -490,6 +491,11 @@ class CollectionMatchersTest : WordSpec() {
             val list = listOf(1, 2, 3)
             list.shouldExist { it == 2 }
          }
+         "give descriptive message when predicate should not match" {
+            shouldThrowAny {
+               listOf(1, 2, 3, 2) shouldNot exist { it == 2}
+            }.message shouldBe "Collection [1, 2, 3, 2] should not contain an element that matches the predicate (kotlin.Int) -> kotlin.Boolean, but elements with the following indexes matched: [1, 3]"
+         }
       }
 
       "shouldHaveAtLeastSize" should {