Fix default base classloader initialization for scripting hosts

also refactor runner functions
#KT-37823 fixed

libraries/scripting/jvm/src/kotlin/script/experimental/jvm/jvmScriptingHostConfiguration.kt

@@ -30,7 +30,7 @@ val JvmScriptingHostConfigurationKeys.jdkHome by PropertiesCollection.key<File>(
 val JvmScriptingHostConfigurationKeys.baseClassLoader by PropertiesCollection.key<ClassLoader>(
     {
         get(ScriptingHostConfiguration.configurationDependencies)?.let {
-            URLClassLoader(it.toClassPathOrEmpty().map { f -> f.toURI().toURL() }.toTypedArray())
+            URLClassLoader(it.toClassPathOrEmpty().map { f -> f.toURI().toURL() }.toTypedArray(), null)
         }
     },
     isTransient = true

libraries/tools/kotlin-main-kts-test/test/org/jetbrains/kotlin/mainKts/test/mainKtsIT.kt

@@ -9,6 +9,7 @@ import junit.framework.Assert
 import org.jetbrains.kotlin.mainKts.COMPILED_SCRIPTS_CACHE_DIR_ENV_VAR
 import org.jetbrains.kotlin.mainKts.COMPILED_SCRIPTS_CACHE_DIR_PROPERTY
 import org.jetbrains.kotlin.scripting.compiler.plugin.runWithK2JVMCompiler
+import org.jetbrains.kotlin.scripting.compiler.plugin.runWithKotlinLauncherScript
 import org.jetbrains.kotlin.scripting.compiler.plugin.runWithKotlinc
 import org.junit.Ignore
 import org.junit.Test
@@ -46,6 +47,19 @@ class MainKtsIT {
     fun testThreadContextClassLoader() {
         runWithKotlincAndMainKts("$TEST_DATA_ROOT/context-classloader.main.kts", listOf("MainKtsConfigurator"))
     }
+
+    @Test
+    fun testCachedReflection() {
+        val cache = createTempDir("main.kts.test")
+
+        try {
+            runWithKotlinRunner("$TEST_DATA_ROOT/use-reflect.main.kts", listOf("false"), cacheDir = cache)
+            // second run uses the cached script
+            runWithKotlinRunner("$TEST_DATA_ROOT/use-reflect.main.kts", listOf("false"), cacheDir = cache)
+        } finally {
+            cache.deleteRecursively()
+        }
+    }
 }
 
 fun runWithKotlincAndMainKts(
@@ -65,6 +79,18 @@ fun runWithKotlincAndMainKts(
     )
 }
 
+fun runWithKotlinRunner(
+    scriptPath: String,
+    expectedOutPatterns: List<String> = emptyList(),
+    expectedExitCode: Int = 0,
+    cacheDir: File? = null
+) {
+    runWithKotlinLauncherScript(
+        "kotlin", listOf(scriptPath), expectedOutPatterns, expectedExitCode,
+        additionalEnvVars = listOf(COMPILED_SCRIPTS_CACHE_DIR_ENV_VAR to (cacheDir?.absolutePath ?: ""))
+    )
+}
+
 fun runWithK2JVMCompilerAndMainKts(
     scriptPath: String,
     expectedOutPatterns: List<String> = emptyList(),

libraries/tools/kotlin-main-kts-test/testData/use-reflect.main.kts

@@ -0,0 +1,2 @@
+
+println(""::class.isOpen)

plugins/scripting/scripting-compiler/tests/org/jetbrains/kotlin/scripting/compiler/plugin/testUtil.kt

@@ -33,18 +33,17 @@ fun runWithKotlinc(
     )
 }
 
-fun runWithKotlinc(
-    compilerArgs: Array<String>,
+fun runWithKotlinLauncherScript(
+    launcherScriptName: String,
+    compilerArgs: Iterable<String>,
     expectedOutPatterns: List<String> = emptyList(),
     expectedExitCode: Int = 0,
     workDirectory: File? = null,
     classpath: List<File> = emptyList(),
     additionalEnvVars: Iterable<Pair<String, String>>? = null
 ) {
-    val executableName = "kotlinc"
-    // TODO:
     val executableFileName =
-        if (System.getProperty("os.name").contains("windows", ignoreCase = true)) "$executableName.bat" else executableName
+        if (System.getProperty("os.name").contains("windows", ignoreCase = true)) "$launcherScriptName.bat" else launcherScriptName
     val launcherFile = File("dist/kotlinc/bin/$executableFileName")
     Assert.assertTrue("Launcher script not found, run dist task: ${launcherFile.absolutePath}", launcherFile.exists())
 
@@ -55,6 +54,30 @@ fun runWithKotlinc(
         }
         addAll(compilerArgs)
     }
+
+    runAndCheckResults(args, expectedOutPatterns, expectedExitCode, workDirectory, additionalEnvVars)
+}
+
+fun runWithKotlinc(
+    compilerArgs: Array<String>,
+    expectedOutPatterns: List<String> = emptyList(),
+    expectedExitCode: Int = 0,
+    workDirectory: File? = null,
+    classpath: List<File> = emptyList(),
+    additionalEnvVars: Iterable<Pair<String, String>>? = null
+) {
+    runWithKotlinLauncherScript(
+        "kotlinc", compilerArgs.asIterable(), expectedOutPatterns, expectedExitCode, workDirectory, classpath, additionalEnvVars
+    )
+}
+
+fun runAndCheckResults(
+    args: List<String>,
+    expectedOutPatterns: List<String> = emptyList(),
+    expectedExitCode: Int = 0,
+    workDirectory: File? = null,
+    additionalEnvVars: Iterable<Pair<String, String>>? = null
+) {
     val processBuilder = ProcessBuilder(args)
     if (workDirectory != null) {
         processBuilder.directory(workDirectory)