From 6669b93c6aec1ad676ad5f6ac6e1cb0119253edc Mon Sep 17 00:00:00 2001
From: Marc Philipp <mail@marcphilipp.de>
Date: Mon, 14 Apr 2025 11:36:21 +0200
Subject: [PATCH 1/2] Relax Kotlin contracts for `Executable` parameters

Since `Executable` is allowed/expected to throw exceptions, the
semantics of being called `EXACTLY_ONCE` are blurry because it might not
be executed entirely when throwing an exception. Since the Kotlin 2.1
compiler emits a warning for these parameters, we're relaxing their
contracts to be called `AT_MOST_ONCE` instead.
---
 .../kotlin/org/junit/jupiter/api/Assertions.kt     | 14 +++++++-------
 .../api/KotlinAssertTimeoutAssertionsTests.kt      | 12 ++++++------
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/junit-jupiter-api/src/main/kotlin/org/junit/jupiter/api/Assertions.kt b/junit-jupiter-api/src/main/kotlin/org/junit/jupiter/api/Assertions.kt
index 44c13138a03d..a3dcbce59eb9 100644
--- a/junit-jupiter-api/src/main/kotlin/org/junit/jupiter/api/Assertions.kt
+++ b/junit-jupiter-api/src/main/kotlin/org/junit/jupiter/api/Assertions.kt
@@ -351,7 +351,7 @@ inline fun <reified T : Throwable> assertThrows(
 @API(status = STABLE, since = "5.11")
 inline fun <R> assertDoesNotThrow(executable: () -> R): R {
     contract {
-        callsInPlace(executable, EXACTLY_ONCE)
+        callsInPlace(executable, AT_MOST_ONCE)
     }
 
     return Assertions.assertDoesNotThrow(evaluateAndWrap(executable))
@@ -374,7 +374,7 @@ inline fun <R> assertDoesNotThrow(
     executable: () -> R
 ): R {
     contract {
-        callsInPlace(executable, EXACTLY_ONCE)
+        callsInPlace(executable, AT_MOST_ONCE)
     }
 
     return assertDoesNotThrow({ message }, executable)
@@ -397,7 +397,7 @@ inline fun <R> assertDoesNotThrow(
     executable: () -> R
 ): R {
     contract {
-        callsInPlace(executable, EXACTLY_ONCE)
+        callsInPlace(executable, AT_MOST_ONCE)
         callsInPlace(message, AT_MOST_ONCE)
     }
 
@@ -411,7 +411,7 @@ inline fun <R> assertDoesNotThrow(
 @PublishedApi
 internal inline fun <R> evaluateAndWrap(executable: () -> R): ThrowingSupplier<R> {
     contract {
-        callsInPlace(executable, EXACTLY_ONCE)
+        callsInPlace(executable, AT_MOST_ONCE)
     }
 
     return try {
@@ -439,7 +439,7 @@ fun <R> assertTimeout(
     executable: () -> R
 ): R {
     contract {
-        callsInPlace(executable, EXACTLY_ONCE)
+        callsInPlace(executable, AT_MOST_ONCE)
     }
 
     return Assertions.assertTimeout(timeout, executable)
@@ -463,7 +463,7 @@ fun <R> assertTimeout(
     executable: () -> R
 ): R {
     contract {
-        callsInPlace(executable, EXACTLY_ONCE)
+        callsInPlace(executable, AT_MOST_ONCE)
     }
 
     return Assertions.assertTimeout(timeout, executable, message)
@@ -487,7 +487,7 @@ fun <R> assertTimeout(
     executable: () -> R
 ): R {
     contract {
-        callsInPlace(executable, EXACTLY_ONCE)
+        callsInPlace(executable, AT_MOST_ONCE)
         callsInPlace(message, AT_MOST_ONCE)
     }
 
diff --git a/jupiter-tests/src/test/kotlin/org/junit/jupiter/api/KotlinAssertTimeoutAssertionsTests.kt b/jupiter-tests/src/test/kotlin/org/junit/jupiter/api/KotlinAssertTimeoutAssertionsTests.kt
index a10d58420c8d..9fad8fd659bb 100644
--- a/jupiter-tests/src/test/kotlin/org/junit/jupiter/api/KotlinAssertTimeoutAssertionsTests.kt
+++ b/jupiter-tests/src/test/kotlin/org/junit/jupiter/api/KotlinAssertTimeoutAssertionsTests.kt
@@ -156,8 +156,8 @@ internal class KotlinAssertTimeoutAssertionsTests {
     }
 
     @Test
-    fun `assertTimeout with value initialization in lambda`() {
-        val value: Int
+    fun `assertTimeout with value assignment in lambda`() {
+        var value = 0
 
         assertTimeout(ofMillis(500)) { value = 10 }
 
@@ -165,8 +165,8 @@ internal class KotlinAssertTimeoutAssertionsTests {
     }
 
     @Test
-    fun `assertTimeout with message and value initialization in lambda`() {
-        val value: Int
+    fun `assertTimeout with message and value assignment in lambda`() {
+        var value = 0
 
         assertTimeout(ofMillis(500), "message") { value = 10 }
 
@@ -174,8 +174,8 @@ internal class KotlinAssertTimeoutAssertionsTests {
     }
 
     @Test
-    fun `assertTimeout with message supplier and value initialization in lambda`() {
-        val value: Int
+    fun `assertTimeout with message supplier and value assignment in lambda`() {
+        var value = 0
 
         @Suppress("ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE")
         val valueInMessageSupplier: Int

From ab26f26dd0000cefbcf83b558b0f8bc8426ecc24 Mon Sep 17 00:00:00 2001
From: Marc Philipp <mail@marcphilipp.de>
Date: Mon, 14 Apr 2025 11:37:03 +0200
Subject: [PATCH 2/2] Treat Kotlin compiler warnings as errors again

Now that #4371 is resolved.
---
 junit-jupiter-api/junit-jupiter-api.gradle.kts | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/junit-jupiter-api/junit-jupiter-api.gradle.kts b/junit-jupiter-api/junit-jupiter-api.gradle.kts
index 7932c998c884..402b5323eb57 100644
--- a/junit-jupiter-api/junit-jupiter-api.gradle.kts
+++ b/junit-jupiter-api/junit-jupiter-api.gradle.kts
@@ -22,10 +22,6 @@ dependencies {
 }
 
 tasks {
-	compileKotlin {
-		// https://github.com/junit-team/junit5/issues/4371
-		compilerOptions.allWarningsAsErrors = false
-	}
 	jar {
 		bundle {
 			val version = project.version