ensure project leak hunter is started (when first test which init the app is UsefulTestCase, then initial val of ourDebugMode is false and it would be restored in tearDown, afterwards only explicit setting to true would help)

platform/platform-impl/src/com/intellij/openapi/application/impl/ApplicationImpl.java

@@ -163,8 +163,7 @@ public class ApplicationImpl extends PlatformComponentManagerImpl implements App
 
     AWTExceptionHandler.register(); // do not crash AWT on exceptions
 
-    String debugDisposer = System.getProperty("idea.disposer.debug");
-    Disposer.setDebugMode((isInternal || isUnitTestMode || "on".equals(debugDisposer)) && !"off".equals(debugDisposer));
+    Disposer.setDebugMode((isInternal || isUnitTestMode || Disposer.isDebugDisposerOn()));
 
     myStartTime = System.currentTimeMillis();
     mySplash = splash;

platform/smRunner/testSrc/com/intellij/execution/testframework/sm/runner/BaseSMTRunnerTestCase.java

@@ -18,6 +18,7 @@ package com.intellij.execution.testframework.sm.runner;
 import com.intellij.execution.configurations.ModuleRunConfiguration;
 import com.intellij.execution.executors.DefaultDebugExecutor;
 import com.intellij.execution.testframework.TestConsoleProperties;
+import com.intellij.openapi.util.Disposer;
 import com.intellij.testFramework.LightPlatformTestCase;
 
 /**
@@ -35,6 +36,13 @@ public abstract class BaseSMTRunnerTestCase extends LightPlatformTestCase {
     mySimpleTest = createTestProxy();
   }
 
+  @Override
+  protected void tearDown() throws Exception {
+    if (mySuite != null) Disposer.dispose(mySuite);
+    if (mySimpleTest != null) Disposer.dispose(mySimpleTest);
+    super.tearDown();
+  }
+
   protected SMTestProxy createTestProxy() {
     return createTestProxy("test");
   }

platform/testFramework/src/_LastInSuiteTest.java

@@ -42,6 +42,12 @@ import java.util.concurrent.TimeUnit;
  */
 @SuppressWarnings("JUnitTestClassNamingConvention")
 public class _LastInSuiteTest extends TestCase {
+  @Override
+  protected void setUp() throws Exception {
+    super.setUp();
+    Disposer.setDebugMode(true);
+  }
+
   public void testProjectLeak() throws Exception {
     boolean guiTestMode = Boolean.getBoolean("idea.test.guimode");
     if (guiTestMode) {

platform/testFramework/src/com/intellij/testFramework/UsefulTestCase.java

@@ -147,7 +147,7 @@ public abstract class UsefulTestCase extends TestCase {
     boolean isStressTest = isStressTest();
     ApplicationInfoImpl.setInStressTest(isStressTest);
     // turn off Disposer debugging for performance tests
-    oldDisposerDebug = Disposer.setDebugMode(Disposer.isDebugMode() && !isStressTest);
+    Disposer.setDebugMode(!isStressTest);
   }
 
   @Override
@@ -158,7 +158,6 @@ public abstract class UsefulTestCase extends TestCase {
       cleanupDeleteOnExitHookList();
     }
     finally {
-      Disposer.setDebugMode(oldDisposerDebug);
       if (shouldContainTempFiles()) {
         FileUtil.resetCanonicalTempPathCache(ORIGINAL_TEMP_DIR);
         if (hasTmpFilesToKeep()) {

platform/util/src/com/intellij/openapi/util/Disposer.java

@@ -56,6 +56,11 @@ public class Disposer {
     }
   };
 
+  private static String debugDisposer = System.getProperty("idea.disposer.debug");
+  public static boolean isDebugDisposerOn() {
+    return "on".equals(debugDisposer);
+  }
+
   private static boolean ourDebugMode;
 
   private Disposer() {
@@ -144,7 +149,10 @@ public class Disposer {
   /**
    * @return old value
    */
-  public static boolean setDebugMode(final boolean debugMode) {
+  public static boolean setDebugMode(boolean debugMode) {
+    if (debugMode) {
+      debugMode = !"off".equals(debugDisposer);
+    }
     boolean oldValue = ourDebugMode;
     ourDebugMode = debugMode;
     return oldValue;