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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.
+//
+// Author: wan@google.com (Zhanyong Wan)
+
+// This sample teaches how to reuse a test fixture in multiple test
+// cases by deriving sub-fixtures from it.
+//
+// When you define a test fixture, you specify the name of the test
+// case that will use this fixture.  Therefore, a test fixture can
+// be used by only one test case.
+//
+// Sometimes, more than one test cases may want to use the same or
+// slightly different test fixtures.  For example, you may want to
+// make sure that all tests for a GUI library don't leak important
+// system resources like fonts and brushes.  In Google Test, you do
+// this by putting the shared logic in a super (as in "super class")
+// test fixture, and then have each test case use a fixture derived
+// from this super fixture.
+
+#include <limits.h>
+#include <time.h>
+#include "sample3-inl.h"
+#include "gtest/gtest.h"
+#include "sample1.h"
+
+// In this sample, we want to ensure that every test finishes within
+// ~5 seconds.  If a test takes longer to run, we consider it a
+// failure.
+//
+// We put the code for timing a test in a test fixture called
+// "QuickTest".  QuickTest is intended to be the super fixture that
+// other fixtures derive from, therefore there is no test case with
+// the name "QuickTest".  This is OK.
+//
+// Later, we will derive multiple test fixtures from QuickTest.
+class QuickTest : public testing::Test {
+ protected:
+  // Remember that SetUp() is run immediately before a test starts.
+  // This is a good place to record the start time.
+  virtual void SetUp() {
+    start_time_ = time(NULL);
+  }
+
+  // TearDown() is invoked immediately after a test finishes.  Here we
+  // check if the test was too slow.
+  virtual void TearDown() {
+    // Gets the time when the test finishes
+    const time_t end_time = time(NULL);
+
+    // Asserts that the test took no more than ~5 seconds.  Did you
+    // know that you can use assertions in SetUp() and TearDown() as
+    // well?
+    EXPECT_TRUE(end_time - start_time_ <= 5) << "The test took too long.";
+  }
+
+  // The UTC time (in seconds) when the test starts
+  time_t start_time_;
+};
+
+
+// We derive a fixture named IntegerFunctionTest from the QuickTest
+// fixture.  All tests using this fixture will be automatically
+// required to be quick.
+class IntegerFunctionTest : public QuickTest {
+  // We don't need any more logic than already in the QuickTest fixture.
+  // Therefore the body is empty.
+};
+
+
+// Now we can write tests in the IntegerFunctionTest test case.
+
+// Tests Factorial()
+TEST_F(IntegerFunctionTest, Factorial) {
+  // Tests factorial of negative numbers.
+  EXPECT_EQ(1, Factorial(-5));
+  EXPECT_EQ(1, Factorial(-1));
+  EXPECT_GT(Factorial(-10), 0);
+
+  // Tests factorial of 0.
+  EXPECT_EQ(1, Factorial(0));
+
+  // Tests factorial of positive numbers.
+  EXPECT_EQ(1, Factorial(1));
+  EXPECT_EQ(2, Factorial(2));
+  EXPECT_EQ(6, Factorial(3));
+  EXPECT_EQ(40320, Factorial(8));
+}
+
+
+// Tests IsPrime()
+TEST_F(IntegerFunctionTest, IsPrime) {
+  // Tests negative input.
+  EXPECT_FALSE(IsPrime(-1));
+  EXPECT_FALSE(IsPrime(-2));
+  EXPECT_FALSE(IsPrime(INT_MIN));
+
+  // Tests some trivial cases.
+  EXPECT_FALSE(IsPrime(0));
+  EXPECT_FALSE(IsPrime(1));
+  EXPECT_TRUE(IsPrime(2));
+  EXPECT_TRUE(IsPrime(3));
+
+  // Tests positive input.
+  EXPECT_FALSE(IsPrime(4));
+  EXPECT_TRUE(IsPrime(5));
+  EXPECT_FALSE(IsPrime(6));
+  EXPECT_TRUE(IsPrime(23));
+}
+
+
+// The next test case (named "QueueTest") also needs to be quick, so
+// we derive another fixture from QuickTest.
+//
+// The QueueTest test fixture has some logic and shared objects in
+// addition to what's in QuickTest already.  We define the additional
+// stuff inside the body of the test fixture, as usual.
+class QueueTest : public QuickTest {
+ protected:
+  virtual void SetUp() {
+    // First, we need to set up the super fixture (QuickTest).
+    QuickTest::SetUp();
+
+    // Second, some additional setup for this fixture.
+    q1_.Enqueue(1);
+    q2_.Enqueue(2);
+    q2_.Enqueue(3);
+  }
+
+  // By default, TearDown() inherits the behavior of
+  // QuickTest::TearDown().  As we have no additional cleaning work
+  // for QueueTest, we omit it here.
+  //
+  // virtual void TearDown() {
+  //   QuickTest::TearDown();
+  // }
+
+  Queue<int> q0_;
+  Queue<int> q1_;
+  Queue<int> q2_;
+};
+
+
+// Now, let's write tests using the QueueTest fixture.
+
+// Tests the default constructor.
+TEST_F(QueueTest, DefaultConstructor) {
+  EXPECT_EQ(0u, q0_.Size());
+}
+
+// Tests Dequeue().
+TEST_F(QueueTest, Dequeue) {
+  int* n = q0_.Dequeue();
+  EXPECT_TRUE(n == NULL);
+
+  n = q1_.Dequeue();
+  EXPECT_TRUE(n != NULL);
+  EXPECT_EQ(1, *n);
+  EXPECT_EQ(0u, q1_.Size());
+  delete n;
+
+  n = q2_.Dequeue();
+  EXPECT_TRUE(n != NULL);
+  EXPECT_EQ(2, *n);
+  EXPECT_EQ(1u, q2_.Size());
+  delete n;
+}
+
+// If necessary, you can derive further test fixtures from a derived
+// fixture itself.  For example, you can derive another fixture from
+// QueueTest.  Google Test imposes no limit on how deep the hierarchy
+// can be.  In practice, however, you probably don't want it to be too
+// deep as to be confusing.