Better handling of large files.

dart/tests/try/cursor_position_test.dart

Index: dart/tests/try/cursor_position_test.dart
diff --git a/dart/tests/try/cursor_position_test.dart b/dart/tests/try/cursor_position_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..fc59691e22fb1c660dad5b1571c3aa54d68974ed
--- /dev/null
+++ b/dart/tests/try/cursor_position_test.dart
@@ -0,0 +1,144 @@
+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// SharedOptions=--package-root=sdk/lib/_internal/
+
+// Test that cursor positions are correctly updated after adding new content.
+
+library trydart.cursor_position_test;
+
+import 'dart:html';
+import 'dart:async';
+
+import '../../site/try/src/interaction_manager.dart' show
+    InteractionManager;
+
+import '../../site/try/src/ui.dart' show
+    hackDiv,
+    mainEditorPane,
+    observer;
+
+import '../../site/try/src/user_option.dart' show
+    UserOption;
+
+import '../../pkg/expect/lib/expect.dart';
+
+import '../../pkg/async_helper/lib/async_helper.dart';
+
+void main() {
+  InteractionManager interaction = mockTryDartInteraction();
+
+  List<TestCase> tests = <TestCase>[
+
+    new TestCase('Test adding two lines programmatically.', () {
+      clearEditorPaneWithoutNotifications();
+      mainEditorPane.appendText('\n\n');
+      Text text = mainEditorPane.firstChild;
+      window.getSelection().collapse(text, 1);
+      checkSelectionIsCollapsed(text, 1);
+    }, checkAtBeginningOfSecondLine),
+
+    new TestCase('Test adding a new line with mock key event.', () {
+      clearEditorPaneWithoutNotifications();
+      checkSelectionIsCollapsed(mainEditorPane, 0);
+      simulateEnterKeyDown(interaction);
+    }, checkAtBeginningOfSecondLine),
+
+  ];
+
+  runTests(tests.iterator, completerForAsyncTest());
+}
+
+void simulateEnterKeyDown(Interaction interaction) {
+  interaction.onKeyUp(
+      new MockKeyboardEvent('keydown', keyCode: KeyCode.ENTER));
+}
+
+void clearEditorPaneWithoutNotifications() {
+  mainEditorPane.nodes.clear();
+  observer.takeRecords();
+}
+
+void checkSelectionIsCollapsed(Node node, int offset) {
+  var selection = window.getSelection();
+  Expect.isTrue(selection.isCollapsed, 'selection.isCollapsed');
+  Expect.equals(node, selection.anchorNode, 'selection.anchorNode');
+  Expect.equals(offset, selection.anchorOffset, 'selection.anchorOffset');
+}
+
+void checkLineCount(int expectedLineCount) {
+  Expect.equals(
+      expectedLineCount, mainEditorPane.nodes.length,
+      'mainEditorPane.nodes.length');
+}
+
+void checkAtBeginningOfSecondLine() {
+  checkLineCount(2);
+  checkSelectionIsCollapsed(mainEditorPane.nodes[1].firstChild, 0);
+}
+
+runTests(Iterator<TestCase> iterator, Completer completer) {
+  if (iterator.moveNext()) {
+    TestCase test = iterator.current;
+    new Future(() {
+      print('${test.description}\nSetup.');
+      test.setup();
+      new Future(() {
+        test.validate();
+        print('${test.description}\nDone.');
+        runTests(iterator, completer);
+      });
+    });
+  } else {
+    completer.complete(null);
+  }
+}
+
+Completer completerForAsyncTest() {
+  Completer completer = new Completer();
+  asyncTest(() => completer.future.then((_) {
+    // Clear the DOM to work around a bug in test.dart.
+    document.body.nodes.clear();
+  }));
+  return completer;
+}
+
+InteractionManager mockTryDartInteraction() {
+  UserOption.storage = {};
+
+  InteractionManager interaction = new InteractionManager();
+
+  hackDiv = new DivElement();
+  mainEditorPane = new DivElement()
+      ..style.whiteSpace = 'pre'
+      ..contentEditable = 'true';
+
+  observer = new MutationObserver(interaction.onMutation);
+  observer.observe(
+      mainEditorPane, childList: true, characterData: true, subtree: true);
+
+  document.body.nodes.addAll([mainEditorPane, hackDiv]);
+
+  return interaction;
+}
+
+class MockKeyboardEvent extends KeyEvent {
+  final int keyCode;
+
+  MockKeyboardEvent(String type, {int keyCode})
+      : this.keyCode = keyCode,
+        super.wrap(new KeyEvent(type, keyCode: keyCode));
+
+  bool getModifierState(String keyArgument) => false;
+}
+
+typedef void VoidFunction();
+
+class TestCase {
+  final String description;
+  final VoidFunction setup;
+  final VoidFunction validate;
+
+  TestCase(this.description, this.setup, this.validate);
+}