[ij-light] IJPL-218999 Preserve ProjectViewPane state when the pane is removed from the ProjectView

IJ-light switches "local" project pane to "RD" project pane, and the state should be preserved during this switch.

GitOrigin-RevId: e2105ee23f5b4d10510a74df0ba3cff543a5c6f7

java/java-tests/testSrc/com/intellij/projectView/ProjectViewSwitchingTest.java

@@ -17,37 +17,44 @@ package com.intellij.projectView;
 
 import com.intellij.JavaTestUtil;
 import com.intellij.ide.projectView.ProjectView;
+import com.intellij.ide.projectView.impl.ProjectViewImpl;
 import com.intellij.ide.projectView.impl.ProjectViewPane;
-import com.intellij.testFramework.TestSourceBasedTestCase;
+import com.intellij.openapi.vfs.VirtualFile;
 
-public class ProjectViewSwitchingTest extends TestSourceBasedTestCase {
+public class ProjectViewSwitchingTest extends AbstractProjectViewTest {
   @Override
   protected String getTestPath() {
     return "projectView";
   }
 
-  public void testSelectProject() {
+  public void testRemoveAddProjectPane() {
     ProjectView projectView = ProjectView.getInstance(getProject());
     projectView.changeView(ProjectViewPane.ID);
-
     assertEquals(ProjectViewPane.ID, projectView.getCurrentViewId());
 
-    //FavoritesManager favoritesManager = FavoritesManager.getInstance(getProject());
-    //favoritesManager.createNewList("xxxx");
-    //
-    //AbstractProjectViewPane currentPane = projectView.getCurrentProjectViewPane();
-    //assertEquals(FavoritesProjectViewPane.ID, currentPane.getId());
-    //assertEquals("xxxx", currentPane.getSubId());
-    //
-    //favoritesManager.createNewList("yyyy");
-    //currentPane = projectView.getCurrentProjectViewPane();
-    //assertEquals(FavoritesProjectViewPane.ID, currentPane.getId());
-    //assertEquals("yyyy", currentPane.getSubId());
-    //
-    //favoritesManager.removeFavoritesList("xxxx");
-    //currentPane = projectView.getCurrentProjectViewPane();
-    //assertEquals(FavoritesProjectViewPane.ID, currentPane.getId());
-    //assertEquals("yyyy", currentPane.getSubId());
+    VirtualFile class1 = getContentRoot().findFileByRelativePath("src/com/package1/Class1.java");
+    selectFile(class1);
+    String expectedTreeStructure = """
+       -PsiDirectory: removeAddProjectPane
+        -PsiDirectory: src
+         -PsiDirectory: com
+          -PsiDirectory: package1
+           Class1
+           +Class2.java
+           Class4.java
+           Form1
+       +External Libraries
+      """;
+
+    createTreeTest().assertStructure(expectedTreeStructure);
+
+    projectView.removeProjectPane(projectView.getProjectViewPaneById(ProjectViewPane.ID));
+    ((ProjectViewImpl)projectView).addProjectPane(new ProjectViewPane(getProject()), true);
+    projectView.changeView(ProjectViewPane.ID);
+
+    // it is important that we create a new instance of the TreeTestUtil (createTreeTest()) here,
+    // because the old one has captured a reference to the old project view tree
+    createTreeTest().assertStructure(expectedTreeStructure); // addProjectPane should restore state
   }
 
   @Override

platform/lang-impl/src/com/intellij/ide/projectView/impl/ProjectViewImpl.java

@@ -743,6 +743,11 @@ public class ProjectViewImpl extends ProjectView implements PersistentStateCompo
   @ApiStatus.Internal
   @CalledInAny
   public synchronized void addProjectPane(final @NotNull AbstractProjectViewPane pane, boolean restoreState) {
+    if (idToPane.containsKey(pane.getId())) {
+      LOG.error("Pane with ID=" + pane.getId() + " already exists. Please remove it first with removeProjectPane(pane).");
+      removeProjectPane(idToPane.get(pane.getId()));
+    }
+
     uninitializedPanes.add(pane);
     if (restoreState) {
       applyUninitializedPaneState(pane);
@@ -771,10 +776,15 @@ public class ProjectViewImpl extends ProjectView implements PersistentStateCompo
   @Override
   public synchronized void removeProjectPane(@NotNull AbstractProjectViewPane pane) {
     ThreadingAssertions.assertEventDispatchThread();
-    uninitializedPanes.remove(pane);
     //assume we are completely initialized here
     @NotNull String idToRemove = pane.getId();
 
+    var oldPaneState = getPaneState(pane);
+    if (oldPaneState != null) {
+      myUninitializedPaneState.put(idToRemove, oldPaneState);
+    }
+    uninitializedPanes.remove(pane);
+
     if (!idToPane.containsKey(idToRemove)) return;
     for (int i = getContentManager().getContentCount() - 1; i >= 0; i--) {
       Content content = getContentManager().getContent(i);
@@ -1523,14 +1533,8 @@ public class ProjectViewImpl extends ProjectView implements PersistentStateCompo
 
   private void writePaneState(@NotNull Element panesElement) {
     for (AbstractProjectViewPane pane : idToPane.values()) {
-      Element paneElement = new Element(ELEMENT_PANE);
-      paneElement.setAttribute(ATTRIBUTE_ID, pane.getId());
-      try {
-        pane.writeExternal(paneElement);
-      }
-      catch (WriteExternalException e) {
-        continue;
-      }
+      Element paneElement = getPaneState(pane);
+      if (paneElement == null) continue;
       panesElement.addContent(paneElement);
     }
     for (Element element : myUninitializedPaneState.values()) {
@@ -1538,6 +1542,18 @@ public class ProjectViewImpl extends ProjectView implements PersistentStateCompo
     }
   }
 
+  private static @Nullable Element getPaneState(AbstractProjectViewPane pane) {
+    Element paneElement = new Element(ELEMENT_PANE);
+    paneElement.setAttribute(ATTRIBUTE_ID, pane.getId());
+    try {
+      pane.writeExternal(paneElement);
+    }
+    catch (WriteExternalException e) {
+      return null;
+    }
+    return paneElement;
+  }
+
   private static ProjectViewSharedSettings getGlobalOptions() {
     return ProjectViewSharedSettings.Companion.getInstance();
   }