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+// Copyright 2005, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// A sample program demonstrating using Google C++ testing framework.
+//
+// Author: wan@google.com (Zhanyong Wan)
+
+
+// In this example, we use a more advanced feature of Google Test called
+// test fixture.
+//
+// A test fixture is a place to hold objects and functions shared by
+// all tests in a test case.  Using a test fixture avoids duplicating
+// the test code necessary to initialize and cleanup those common
+// objects for each test.  It is also useful for defining sub-routines
+// that your tests need to invoke a lot.
+//
+// <TechnicalDetails>
+//
+// The tests share the test fixture in the sense of code sharing, not
+// data sharing.  Each test is given its own fresh copy of the
+// fixture.  You cannot expect the data modified by one test to be
+// passed on to another test, which is a bad idea.
+//
+// The reason for this design is that tests should be independent and
+// repeatable.  In particular, a test should not fail as the result of
+// another test's failure.  If one test depends on info produced by
+// another test, then the two tests should really be one big test.
+//
+// The macros for indicating the success/failure of a test
+// (EXPECT_TRUE, FAIL, etc) need to know what the current test is
+// (when Google Test prints the test result, it tells you which test
+// each failure belongs to).  Technically, these macros invoke a
+// member function of the Test class.  Therefore, you cannot use them
+// in a global function.  That's why you should put test sub-routines
+// in a test fixture.
+//
+// </TechnicalDetails>
+
+#include "sample3-inl.h"
+#include "gtest/gtest.h"
+
+// To use a test fixture, derive a class from testing::Test.
+class QueueTest : public testing::Test {
+ protected:  // You should make the members protected s.t. they can be
+             // accessed from sub-classes.
+
+  // virtual void SetUp() will be called before each test is run.  You
+  // should define it if you need to initialize the varaibles.
+  // Otherwise, this can be skipped.
+  virtual void SetUp() {
+    q1_.Enqueue(1);
+    q2_.Enqueue(2);
+    q2_.Enqueue(3);
+  }
+
+  // virtual void TearDown() will be called after each test is run.
+  // You should define it if there is cleanup work to do.  Otherwise,
+  // you don't have to provide it.
+  //
+  // virtual void TearDown() {
+  // }
+
+  // A helper function that some test uses.
+  static int Double(int n) {
+    return 2*n;
+  }
+
+  // A helper function for testing Queue::Map().
+  void MapTester(const Queue<int> * q) {
+    // Creates a new queue, where each element is twice as big as the
+    // corresponding one in q.
+    const Queue<int> * const new_q = q->Map(Double);
+
+    // Verifies that the new queue has the same size as q.
+    ASSERT_EQ(q->Size(), new_q->Size());
+
+    // Verifies the relationship between the elements of the two queues.
+    for ( const QueueNode<int> * n1 = q->Head(), * n2 = new_q->Head();
+          n1 != NULL; n1 = n1->next(), n2 = n2->next() ) {
+      EXPECT_EQ(2 * n1->element(), n2->element());
+    }
+
+    delete new_q;
+  }
+
+  // Declares the variables your tests want to use.
+  Queue<int> q0_;
+  Queue<int> q1_;
+  Queue<int> q2_;
+};
+
+// When you have a test fixture, you define a test using TEST_F
+// instead of TEST.
+
+// Tests the default c'tor.
+TEST_F(QueueTest, DefaultConstructor) {
+  // You can access data in the test fixture here.
+  EXPECT_EQ(0u, q0_.Size());
+}
+
+// Tests Dequeue().
+TEST_F(QueueTest, Dequeue) {
+  int * n = q0_.Dequeue();
+  EXPECT_TRUE(n == NULL);
+
+  n = q1_.Dequeue();
+  ASSERT_TRUE(n != NULL);
+  EXPECT_EQ(1, *n);
+  EXPECT_EQ(0u, q1_.Size());
+  delete n;
+
+  n = q2_.Dequeue();
+  ASSERT_TRUE(n != NULL);
+  EXPECT_EQ(2, *n);
+  EXPECT_EQ(1u, q2_.Size());
+  delete n;
+}
+
+// Tests the Queue::Map() function.
+TEST_F(QueueTest, Map) {
+  MapTester(&q0_);
+  MapTester(&q1_);
+  MapTester(&q2_);
+}