IDEA-61275 Editor: the folded class comment should not be auto-expanded on class declaration editing

1. Corrected fold descriptions construction (specifying the element from java file header at PsiElement  -> Fold region mapping if possible)

java/java-impl/src/com/intellij/codeInsight/folding/impl/JavaFoldingBuilder.java

@@ -77,7 +77,12 @@ public class JavaFoldingBuilder extends FoldingBuilderEx implements DumbAware {
 
     TextRange range = getFileHeader(file);
     if (range != null && range.getLength() > 1 && document.getLineNumber(range.getEndOffset()) > document.getLineNumber(range.getStartOffset())) {
-      result.add(new FoldingDescriptor(file, range));
+      PsiElement anchorElementToUse = file;
+      PsiElement candidate = file.getFirstChild();
+      if (candidate != null && candidate.getTextRange().equals(range)) {
+        anchorElementToUse = candidate;
+      }
+      result.add(new FoldingDescriptor(anchorElementToUse, range));
     }
 
     return result.toArray(new FoldingDescriptor[result.size()]);

platform/platform-impl/testSrc/com/intellij/openapi/editor/impl/AbstractEditorProcessingOnDocumentModificationTest.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2000-2010 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.openapi.editor.impl;
+
+import com.intellij.openapi.editor.FoldRegion;
+import com.intellij.testFramework.LightPlatformCodeInsightTestCase;
+
+import java.io.IOException;
+import java.util.Arrays;
+
+/**
+ * Base super class for tests that check various IJ editor functionality on managed document modification.
+ * <p/>
+ * It's main purpose is to provide utility methods like fold regions addition and setup; typing etc. 
+ * 
+ * @author Denis Zhdanov
+ * @since 11/18/10 7:43 PM
+ */
+public abstract class AbstractEditorProcessingOnDocumentModificationTest extends LightPlatformCodeInsightTestCase {
+  
+  protected void init(String fileText) throws IOException {
+    configureFromFileText(getFileName(), fileText);
+  }
+
+  private String getFileName() {
+    return getTestName(false) + ".txt";
+  }
+
+  protected static void addFoldRegion(final int startOffset, final int endOffset, final String placeholder) {
+    myEditor.getFoldingModel().runBatchFoldingOperation(new Runnable() {
+      @Override
+      public void run() {
+        myEditor.getFoldingModel().addFoldRegion(startOffset, endOffset, placeholder);
+      }
+    });
+  }
+
+  protected static void addCollapsedFoldRegion(final int startOffset, final int endOffset, final String placeholder) {
+    addFoldRegion(startOffset, endOffset, placeholder);
+    toggleFoldRegionState(getFoldRegion(startOffset), false);
+  }
+
+  protected static void toggleFoldRegionState(final FoldRegion foldRegion, final boolean expanded) {
+    myEditor.getFoldingModel().runBatchFoldingOperation(new Runnable() {
+      @Override
+      public void run() {
+        foldRegion.setExpanded(expanded);
+      }
+    });
+  }
+
+  protected static FoldRegion getFoldRegion(int startOffset) {
+    FoldRegion[] foldRegions = myEditor.getFoldingModel().getAllFoldRegions();
+    for (FoldRegion foldRegion : foldRegions) {
+      if (foldRegion.getStartOffset() == startOffset) {
+        return foldRegion;
+      }
+    }
+    throw new IllegalArgumentException(String.format(
+      "Can't find fold region with start offset %d. Registered fold regions: %s. Document text: '%s'",
+      startOffset, Arrays.toString(foldRegions), myEditor.getDocument().getCharsSequence()
+    ));
+  }
+}

platform/platform-impl/testSrc/com/intellij/openapi/editor/impl/FoldingProcessingOnDocumentModificationTest.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2000-2010 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.openapi.editor.impl;
+
+import com.intellij.openapi.editor.CaretModel;
+import com.intellij.openapi.editor.FoldRegion;
+
+import java.io.IOException;
+
+/**
+ * @author Denis Zhdanov
+ * @since 11/18/10 7:42 PM
+ */
+public class FoldingProcessingOnDocumentModificationTest extends AbstractEditorProcessingOnDocumentModificationTest {
+  
+  public void testUnexpectedClassLevelJavadocExpandingOnClassSignatureChange() throws IOException {
+    // Inspired by IDEA-61275
+
+    String text =
+      "/**\n" +
+      " * This is a test comment\n" +
+      " */\n" +
+      "public <caret>class Test {\n" +
+      "}";
+    init(text);
+
+    CaretModel caretModel = myEditor.getCaretModel();
+    int caretOffset = caretModel.getOffset();
+    
+    addCollapsedFoldRegion(0, text.indexOf("public") - 1, "/***/");
+    assertEquals(caretOffset, caretModel.getOffset());
+    
+    type('a');
+
+    assertEquals(caretOffset + 1, caretModel.getOffset());
+    assertEquals(1, myEditor.getFoldingModel().getAllFoldRegions().length);
+    FoldRegion foldRegion = getFoldRegion(0);
+    assertFalse(foldRegion.isExpanded());
+  }
+}

platform/platform-impl/testSrc/com/intellij/openapi/editor/impl/softwrap/mapping/SoftWrapApplianceOnDocumentModificationTest.java

@@ -17,22 +17,19 @@ package com.intellij.openapi.editor.impl.softwrap.mapping;
 
 import com.intellij.openapi.editor.*;
 import com.intellij.openapi.editor.ex.SoftWrapModelEx;
+import com.intellij.openapi.editor.impl.AbstractEditorProcessingOnDocumentModificationTest;
 import com.intellij.openapi.editor.impl.SoftWrapModelImpl;
-import com.intellij.testFramework.LightPlatformCodeInsightTestCase;
 import gnu.trove.TIntHashSet;
 import gnu.trove.TIntProcedure;
 
 import java.awt.*;
 import java.io.IOException;
-import java.util.Arrays;
 
 /**
  * @author Denis Zhdanov
  * @since 09/16/2010
  */
-public class SoftWrapApplianceOnDocumentModificationTest extends LightPlatformCodeInsightTestCase {
-
-  //private static final String PATH = "/codeInsight/softwrap/";
+public class SoftWrapApplianceOnDocumentModificationTest extends AbstractEditorProcessingOnDocumentModificationTest {
 
   @Override
   protected void tearDown() throws Exception {
@@ -243,11 +240,6 @@ public class SoftWrapApplianceOnDocumentModificationTest extends LightPlatformCo
     assertEquals(offset, caretModel.getOffset());
   }
   
-  //private void init(final int visibleWidth) throws Exception {
-  //  configureByFile(PATH + getFileName());
-  //  initCommon(visibleWidth);
-  //}
-
   private static TIntHashSet collectSoftWrapStartOffsets(int documentLine) {
     TIntHashSet result = new TIntHashSet();
     for (SoftWrap softWrap : myEditor.getSoftWrapModel().getSoftWrapsForLine(documentLine)) {
@@ -256,52 +248,8 @@ public class SoftWrapApplianceOnDocumentModificationTest extends LightPlatformCo
     return result;
   }
   
-  private void init(int visibleWidth, String fileText) throws IOException {
-    configureFromFileText(getFileName(), fileText);
-    initCommon(visibleWidth);
-  }
-
-  private String getFileName() {
-    return getTestName(false) + ".txt";
-  }
-
-  private static void addFoldRegion(final int startOffset, final int endOffset, final String placeholder) {
-    myEditor.getFoldingModel().runBatchFoldingOperation(new Runnable() {
-      @Override
-      public void run() {
-        myEditor.getFoldingModel().addFoldRegion(startOffset, endOffset, placeholder);
-      }
-    });
-  }
-
-  private static void addCollapsedFoldRegion(final int startOffset, final int endOffset, final String placeholder) {
-    addFoldRegion(startOffset, endOffset, placeholder);
-    toggleFoldRegionState(getFoldRegion(startOffset), false);
-  }
-
-  private static void toggleFoldRegionState(final FoldRegion foldRegion, final boolean expanded) {
-    myEditor.getFoldingModel().runBatchFoldingOperation(new Runnable() {
-      @Override
-      public void run() {
-        foldRegion.setExpanded(expanded);
-      }
-    });
-  }
-  
-  private static FoldRegion getFoldRegion(int startOffset) {
-    FoldRegion[] foldRegions = myEditor.getFoldingModel().getAllFoldRegions();
-    for (FoldRegion foldRegion : foldRegions) {
-      if (foldRegion.getStartOffset() == startOffset) {
-        return foldRegion;
-      }
-    }
-    throw new IllegalArgumentException(String.format(
-      "Can't find fold region with start offset %d. Registered fold regions: %s. Document text: '%s'",
-      startOffset, Arrays.toString(foldRegions), myEditor.getDocument().getCharsSequence()
-    ));
-  }
-
-  private static void initCommon(final int visibleWidth) {
+  private void init(final int visibleWidth, String fileText) throws IOException {
+    init(fileText);
     myEditor.getSettings().setUseSoftWraps(true);
     SoftWrapModelImpl model = (SoftWrapModelImpl)myEditor.getSoftWrapModel();
     model.refreshSettings();