Add unittest for CircularLinkedList + bugfix

dart/runtime/bin/eventhandler_test.cc

+// Copyright (c) 2012, 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.
+
+#include "platform/assert.h"
+#include "platform/globals.h"
+#include "vm/unit_test.h"
+
+#include "bin/eventhandler.h"
+
+namespace dart {
+namespace bin {
+
+UNIT_TEST_CASE(CircularLinkedList) {
+  CircularLinkedList<int> list;
+
+  EXPECT(!list.HasHead());
+
+  list.Add(1);
+  EXPECT(list.HasHead());
+  EXPECT(list.head() == 1);
+
+
+  // Test: Inserts don't move head.
+  for (int i = 2; i <= 100; i++) {
+    list.Add(i);
+    EXPECT(list.head() == 1);
+  }
+
+
+  // Test: Rotate cycle through all elements in insertion order.
+  for (int i = 1; i <= 100; i++) {
+    EXPECT(list.HasHead());
+    EXPECT(list.head() == i);
+    list.Rotate();
+  }
+
+
+  // Test: Removing head results in next element to be head.
+  for (int i = 1; i <= 100; i++) {
+    list.RemoveHead();
+    for (int j = i + 1; j <= 100; j++) {
+      EXPECT(list.HasHead());
+      EXPECT(list.head() == j);
+      list.Rotate();
+    }
+  }
+
+  // Test: Removing all items individually make list empty.
+  EXPECT(!list.HasHead());
+
+
+  // Test: Removing all items at once makes list empty.
+  for (int i = 1; i <= 100; i++) {
+    list.Add(i);
+  }
+  list.RemoveAll();
+  EXPECT(!list.HasHead());
+
+
+  // Test: Remove individual items just deletes them without modifying head.
+  for (int i = 1; i <= 10; i++) {
+    list.Add(i);
+  }
+  for (int i = 2; i <= 9; i++) {
+    list.Remove(i);
+  }
+  EXPECT(list.head() == 1);
+  list.Rotate();
+  EXPECT(list.head() == 10);
+  list.Rotate();
+  EXPECT(list.head() == 1);
+
+
+  // Test: Remove non-existent element leaves list un-changed.
+  list.Remove(4242);
+  EXPECT(list.head() == 1);
+
+
+  // Test: Remove head element individually moves head to next element.
+  list.Remove(1);
+  EXPECT(list.HasHead());
+  EXPECT(list.head() == 10);
+  list.Remove(10);
+  EXPECT(!list.HasHead());
+
+
+  // Test: Remove non-existent element from empty list works.
+  list.Remove(4242);
+}
+
+}  // namespace bin
+}  // namespace dart