diagnostics for EditorHistoryManagerTest.testSavingStateForNotOpenedEditors

platform/platform-tests/testSrc/com/intellij/openapi/fileEditor/impl/EditorHistoryManagerTest.java

@@ -1,6 +1,7 @@
 // Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package com.intellij.openapi.fileEditor.impl;
 
+import com.intellij.diagnostic.ThreadDumper;
 import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.application.ex.ApplicationManagerEx;
 import com.intellij.openapi.components.impl.ComponentManagerImpl;
@@ -22,6 +23,7 @@ import com.intellij.util.ui.UIUtil;
 import org.jetbrains.annotations.NotNull;
 
 import java.io.File;
+import java.lang.ref.WeakReference;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.util.Arrays;
@@ -45,11 +47,22 @@ public class EditorHistoryManagerTest extends PlatformTestCase {
       FileEditorManager.getInstance(project).closeFile(virtualFile);
     });
 
+    String threadDumpBefore = ThreadDumper.dumpThreadsToString();
+
     GCUtil.tryGcSoftlyReachableObjects();
+
+    WeakReference<Object> weakReference = new WeakReference<>(new Object());
+    do {
+      //noinspection CallToSystemGC
+      System.gc();
+    }
+    while (weakReference.get() != null);
+
     Document document = FileDocumentManager.getInstance().getCachedDocument(virtualFile);
     if (document != null) {
       fail("Document wasn't collected, see heap dump at " + publishHeapDump(EditorHistoryManagerTest.class.getName()));
-      System.out.println("Keeping a reference to the document: " + document);
+      System.err.println("Keeping a reference to the document: " + document);
+      System.err.println(threadDumpBefore);
     }
 
     openProjectPerformTaskCloseProject(dir, project -> {});