text: // Copyright 2009 Google Inc. All Rights Reserved.
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  // notice, this list of conditions and the following disclaimer.
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  // in the documentation and/or other materials provided with the
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  //
  // 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,
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  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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  // (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: vladl@google.com (Vlad Losev)
  
  // This sample shows how to use Google Test listener API to implement
  // a primitive leak checker.
  
  #include <stdio.h>
  #include <stdlib.h>
  
  #include <gtest/gtest.h>
  
  using ::testing::EmptyTestEventListener;
  using ::testing::InitGoogleTest;
  using ::testing::Test;
  using ::testing::TestCase;
  using ::testing::TestEventListeners;
  using ::testing::TestInfo;
  using ::testing::TestPartResult;
  using ::testing::UnitTest;
  
  namespace {
  
  // We will track memory used by this class.
  class Water {
   public:
    // Normal Water declarations go here.
  
    // operator new and operator delete help us control water allocation.
    void* operator new(size_t allocation_size) {
      allocated_++;
      return malloc(allocation_size);
    }
  
    void operator delete(void* block, size_t /* allocation_size */) {
      allocated_--;
      free(block);
    }
  
    static int allocated() { return allocated_; }
  
   private:
    static int allocated_;
  };
  
  int Water::allocated_ = 0;
  
  // This event listener monitors how many Water objects are created and
  // destroyed by each test, and reports a failure if a test leaks some Water
  // objects. It does this by comparing the number of live Water objects at
  // the beginning of a test and at the end of a test.
  class LeakChecker : public EmptyTestEventListener {
   private:
    // Called before a test starts.
    virtual void OnTestStart(const TestInfo& /* test_info */) {
      initially_allocated_ = Water::allocated();
    }
  
    // Called after a test ends.
    virtual void OnTestEnd(const TestInfo& /* test_info */) {
      int difference = Water::allocated() - initially_allocated_;
  
      // You can generate a failure in any event handler except
      // OnTestPartResult. Just use an appropriate Google Test assertion to do
      // it.
      EXPECT_TRUE(difference <= 0)
          << "Leaked " << difference << " unit(s) of Water!";
    }
  
    int initially_allocated_;
  };
  
  TEST(ListenersTest, DoesNotLeak) {
    Water* water = new Water;
    delete water;
  }
  
  // This should fail when the --check_for_leaks command line flag is
  // specified.
  TEST(ListenersTest, LeaksWater) {
    Water* water = new Water;
    EXPECT_TRUE(water != NULL);
  }
  
  }  // namespace
  
  int main(int argc, char **argv) {
    InitGoogleTest(&argc, argv);
  
    bool check_for_leaks = false;
    if (argc > 1 && strcmp(argv[1], "--check_for_leaks") == 0 )
      check_for_leaks = true;
    else
      printf("%s\n", "Run this program with --check_for_leaks to enable "
             "custom leak checking in the tests.");
  
    // If we are given the --check_for_leaks command line flag, installs the
    // leak checker.
    if (check_for_leaks) {
      TestEventListeners& listeners = UnitTest::GetInstance()->listeners();
  
      // Adds the leak checker to the end of the test event listener list,
      // after the default text output printer and the default XML report
      // generator.
      //
      // The order is important - it ensures that failures generated in the
      // leak checker's OnTestEnd() method are processed by the text and XML
      // printers *before* their OnTestEnd() methods are called, such that
      // they are attributed to the right test. Remember that a listener
      // receives an OnXyzStart event *after* listeners preceding it in the
      // list received that event, and receives an OnXyzEnd event *before*
      // listeners preceding it.
      //
      // We don't need to worry about deleting the new listener later, as
      // Google Test will do it.
      listeners.Append(new LeakChecker);
    }
    return RUN_ALL_TESTS();
  }
  