Refactoring: extract resetApplicationToNull to separate file

compiler/tests-common/tests/org/jetbrains/kotlin/test/testFramework/KtUsefulTestCase.java

@@ -51,7 +51,6 @@ import org.jetbrains.kotlin.test.IdeaSystemPropertiesForParallelRunConfigurator;
 import org.jetbrains.kotlin.testFramework.MockComponentManagerCreationTracer;
 import org.jetbrains.kotlin.types.AbstractTypeChecker;
 import org.jetbrains.kotlin.types.FlexibleTypeImpl;
-import org.jetbrains.kotlin.utils.ExceptionUtilsKt;
 import org.junit.Assert;
 
 import java.io.File;
@@ -165,28 +164,11 @@ public abstract class KtUsefulTestCase extends TestCase {
         }
         finally {
             super.tearDown();
-            resetApplicationToNull(application);
+            TestApplicationUtilKt.resetApplicationToNull(application);
             application = null;
         }
     }
 
-    public static void resetApplicationToNull(Application old) {
-        if (old != null) return;
-        resetApplicationToNull();
-    }
-
-    public static void resetApplicationToNull() {
-        try {
-            Field ourApplicationField = ApplicationManager.class.getDeclaredField("ourApplication");
-            ourApplicationField.setAccessible(true);
-            ourApplicationField.set(null, null);
-        }
-        catch (Exception e) {
-            throw ExceptionUtilsKt.rethrow(e);
-        }
-    }
-
-
     protected final void disposeRootDisposable() {
         Disposer.dispose(getTestRootDisposable());
     }

compiler/tests-common/tests/org/jetbrains/kotlin/test/testFramework/TestApplicationUtil.kt

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.test.testFramework
+
+import com.intellij.openapi.application.Application
+import com.intellij.openapi.application.ApplicationManager
+import org.jetbrains.kotlin.utils.rethrow
+import java.lang.reflect.Field
+
+fun resetApplicationToNull(old: Application?) {
+    if (old != null) return
+    resetApplicationToNull()
+}
+
+fun resetApplicationToNull() {
+    try {
+        val ourApplicationField: Field = ApplicationManager::class.java.getDeclaredField("ourApplication")
+        ourApplicationField.setAccessible(true)
+        ourApplicationField.set(null, null)
+    } catch (e: Exception) {
+        throw rethrow(e)
+    }
+}

compiler/tests-common/tests/org/jetbrains/kotlin/testFramework/MockComponentManagerCreationTracer.kt

@@ -19,7 +19,7 @@ package org.jetbrains.kotlin.testFramework
 import com.intellij.mock.MockComponentManager
 import com.intellij.openapi.application.Application
 import com.intellij.util.containers.ContainerUtil
-import org.jetbrains.kotlin.test.testFramework.KtUsefulTestCase
+import org.jetbrains.kotlin.test.testFramework.resetApplicationToNull
 
 object MockComponentManagerCreationTracer {
 
@@ -41,7 +41,7 @@ object MockComponentManagerCreationTracer {
     @JvmStatic
     fun diagnoseDisposedButNotClearedApplication(app: Application) {
         if (app is MockComponentManager) {
-            KtUsefulTestCase.resetApplicationToNull()
+            resetApplicationToNull()
             throw IllegalStateException("Some test disposed, but forgot to clear MockApplication", creationTraceMap[app])
         }
     }