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28
29
30// This sample shows how to use Google Test listener API to implement
31// a primitive leak checker.
32
33#include <stdio.h>
34#include <stdlib.h>
35
36#include "gtest/gtest.h"
37using ::testing::EmptyTestEventListener;
38using ::testing::InitGoogleTest;
39using ::testing::Test;
40using ::testing::TestEventListeners;
41using ::testing::TestInfo;
42using ::testing::TestPartResult;
43using ::testing::UnitTest;
44
45namespace {
46// We will track memory used by this class.
47class Water {
48 public:
49  // Normal Water declarations go here.
50
51  // operator new and operator delete help us control water allocation.
52  void* operator new(size_t allocation_size) {
53    allocated_++;
54    return malloc(allocation_size);
55  }
56
57  void operator delete(void* block, size_t /* allocation_size */) {
58    allocated_--;
59    free(block);
60  }
61
62  static int allocated() { return allocated_; }
63
64 private:
65  static int allocated_;
66};
67
68int Water::allocated_ = 0;
69
70// This event listener monitors how many Water objects are created and
71// destroyed by each test, and reports a failure if a test leaks some Water
72// objects. It does this by comparing the number of live Water objects at
73// the beginning of a test and at the end of a test.
74class LeakChecker : public EmptyTestEventListener {
75 private:
76  // Called before a test starts.
77  virtual void OnTestStart(const TestInfo& /* test_info */) {
78    initially_allocated_ = Water::allocated();
79  }
80
81  // Called after a test ends.
82  virtual void OnTestEnd(const TestInfo& /* test_info */) {
83    int difference = Water::allocated() - initially_allocated_;
84
85    // You can generate a failure in any event handler except
86    // OnTestPartResult. Just use an appropriate Google Test assertion to do
87    // it.
88    EXPECT_LE(difference, 0) << "Leaked " << difference << " unit(s) of Water!";
89  }
90
91  int initially_allocated_;
92};
93
94TEST(ListenersTest, DoesNotLeak) {
95  Water* water = new Water;
96  delete water;
97}
98
99// This should fail when the --check_for_leaks command line flag is
100// specified.
101TEST(ListenersTest, LeaksWater) {
102  Water* water = new Water;
103  EXPECT_TRUE(water != NULL);
104}
105}  // namespace
106
107int main(int argc, char **argv) {
108  InitGoogleTest(&argc, argv);
109
110  bool check_for_leaks = false;
111  if (argc > 1 && strcmp(argv[1], "--check_for_leaks") == 0 )
112    check_for_leaks = true;
113  else
114    printf("%s\n", "Run this program with --check_for_leaks to enable "
115           "custom leak checking in the tests.");
116
117  // If we are given the --check_for_leaks command line flag, installs the
118  // leak checker.
119  if (check_for_leaks) {
120    TestEventListeners& listeners = UnitTest::GetInstance()->listeners();
121
122    // Adds the leak checker to the end of the test event listener list,
123    // after the default text output printer and the default XML report
124    // generator.
125    //
126    // The order is important - it ensures that failures generated in the
127    // leak checker's OnTestEnd() method are processed by the text and XML
128    // printers *before* their OnTestEnd() methods are called, such that
129    // they are attributed to the right test. Remember that a listener
130    // receives an OnXyzStart event *after* listeners preceding it in the
131    // list received that event, and receives an OnXyzEnd event *before*
132    // listeners preceding it.
133    //
134    // We don't need to worry about deleting the new listener later, as
135    // Google Test will do it.
136    listeners.Append(new LeakChecker);
137  }
138  return RUN_ALL_TESTS();
139}
140