[Build] Add ability to set fixed numbers of JUnit 5 threads via local.properties

buildSrc/src/main/kotlin/BuildPropertiesExt.kt

@@ -35,4 +35,7 @@ val KotlinBuildProperties.isObsoleteJdkOverrideEnabled: Boolean
     get() = getBoolean("kotlin.build.isObsoleteJdkOverrideEnabled", false)
 
 val KotlinBuildProperties.isNativeRuntimeDebugInfoEnabled: Boolean
-    get() = getBoolean("kotlin.native.isNativeRuntimeDebugInfoEnabled", false)
+    get() = getBoolean("kotlin.native.isNativeRuntimeDebugInfoEnabled", false)
+
+val KotlinBuildProperties.junit5NumberOfThreadsForParallelExecution: Int?
+    get() = (getOrNull("kotlin.test.junit5.maxParallelForks") as? String)?.toInt()

buildSrc/src/main/kotlin/tasks.kt

@@ -199,6 +199,10 @@ fun Project.projectTest(
         systemProperty("jps.kotlin.home", project.rootProject.extra["distKotlinHomeDir"]!!)
         systemProperty("kotlin.ni", if (project.rootProject.hasProperty("newInferenceTests")) "true" else "false")
         systemProperty("org.jetbrains.kotlin.skip.muted.tests", if (project.rootProject.hasProperty("skipMutedTests")) "true" else "false")
+        project.kotlinBuildProperties.junit5NumberOfThreadsForParallelExecution?.let { n ->
+            systemProperty("junit.jupiter.execution.parallel.config.strategy", "fixed")
+            systemProperty("junit.jupiter.execution.parallel.config.fixed.parallelism", n)
+        }
 
         systemProperty("idea.ignore.disabled.plugins", "true")
 
@@ -319,4 +323,4 @@ abstract class PublishToMavenLocalSerializable : AbstractPublishToMaven() {
             }
         }.run()
     }
-}
+}