Support expand/collapsing hideable implementation detail groups with …

…left and right arrow keys (#8275)

packages/devtools_app/lib/src/screens/inspector_v2/inspector_tree_controller.dart

@@ -319,6 +319,11 @@ class InspectorTreeController extends DisposableController
 
   void navigateLeft() {
     final selectionLocal = selection;
+    final diagnostic = selectionLocal?.diagnostic;
+
+    final toggledHideableGroup =
+        _maybeToggleHideableGroup(diagnostic, showGroup: false);
+    if (toggledHideableGroup) return;
 
     // This logic is consistent with how IntelliJ handles tree navigation on
     // on left arrow key press.
@@ -342,11 +347,16 @@ class InspectorTreeController extends DisposableController
   }
 
   void navigateRight() {
+    final selectionLocal = selection;
+    final diagnostic = selectionLocal?.diagnostic;
+
+    final toggledHideableGroup =
+        _maybeToggleHideableGroup(diagnostic, showGroup: true);
+    if (toggledHideableGroup) return;
+
     // This logic is consistent with how IntelliJ handles tree navigation on
     // on right arrow key press.
 
-    final selectionLocal = selection;
-
     if (selectionLocal == null || selectionLocal.isExpanded) {
       _navigateHelper(1);
       return;
@@ -373,6 +383,31 @@ class InspectorTreeController extends DisposableController
     );
   }
 
+  /// Given [shouldShow], toggles the visibility of a hideable group.
+  ///
+  /// Returns a [bool] representing whether or not the group was toggled.
+  bool _maybeToggleHideableGroup(
+    RemoteDiagnosticsNode? diagnostic, {
+    required bool showGroup,
+  }) {
+    final isHideableGroupLeader =
+        diagnostic != null && diagnostic.isHideableGroupLeader;
+    final shouldToggle = isHideableGroupLeader &&
+        (showGroup ? diagnostic.groupIsHidden : !diagnostic.groupIsHidden);
+
+    if (shouldToggle) {
+      refreshTree(
+        updateTreeAction: () {
+          diagnostic.toggleHiddenGroup();
+          return true;
+        },
+      );
+      return true;
+    }
+
+    return false;
+  }
+
   double get horizontalPadding => 10.0;
 
   /// Returns the indentation of a row at the given [depth] in the inspector.