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29// Author: vladl@google.com (Vlad Losev)
30
31// This sample shows how to use Google Test listener API to implement
32// a primitive leak checker.
33
34#include <stdio.h>
35#include <stdlib.h>
36
37#include "gtest/gtest.h"
38
39using ::testing::EmptyTestEventListener;
40using ::testing::InitGoogleTest;
41using ::testing::Test;
42using ::testing::TestCase;
43using ::testing::TestEventListeners;
44using ::testing::TestInfo;
45using ::testing::TestPartResult;
46using ::testing::UnitTest;
47
48namespace {
49
50// We will track memory used by this class.
51class Water {
52 public:
53  // Normal Water declarations go here.
54
55  // operator new and operator delete help us control water allocation.
56  void* operator new(size_t allocation_size) {
57    allocated_++;
58    return malloc(allocation_size);
59  }
60
61  void operator delete(void* block, size_t /* allocation_size */) {
62    allocated_--;
63    free(block);
64  }
65
66  static int allocated() { return allocated_; }
67
68 private:
69  static int allocated_;
70};
71
72int Water::allocated_ = 0;
73
74// This event listener monitors how many Water objects are created and
75// destroyed by each test, and reports a failure if a test leaks some Water
76// objects. It does this by comparing the number of live Water objects at
77// the beginning of a test and at the end of a test.
78class LeakChecker : public EmptyTestEventListener {
79 private:
80  // Called before a test starts.
81  virtual void OnTestStart(const TestInfo& /* test_info */) {
82    initially_allocated_ = Water::allocated();
83  }
84
85  // Called after a test ends.
86  virtual void OnTestEnd(const TestInfo& /* test_info */) {
87    int difference = Water::allocated() - initially_allocated_;
88
89    // You can generate a failure in any event handler except
90    // OnTestPartResult. Just use an appropriate Google Test assertion to do
91    // it.
92    EXPECT_LE(difference, 0) << "Leaked " << difference << " unit(s) of Water!";
93  }
94
95  int initially_allocated_;
96};
97
98TEST(ListenersTest, DoesNotLeak) {
99  Water* water = new Water;
100  delete water;
101}
102
103// This should fail when the --check_for_leaks command line flag is
104// specified.
105TEST(ListenersTest, LeaksWater) {
106  Water* water = new Water;
107  EXPECT_TRUE(water != NULL);
108}
109
110}  // namespace
111
112int main(int argc, char **argv) {
113  InitGoogleTest(&argc, argv);
114
115  bool check_for_leaks = false;
116  if (argc > 1 && strcmp(argv[1], "--check_for_leaks") == 0 )
117    check_for_leaks = true;
118  else
119    printf("%s\n", "Run this program with --check_for_leaks to enable "
120           "custom leak checking in the tests.");
121
122  // If we are given the --check_for_leaks command line flag, installs the
123  // leak checker.
124  if (check_for_leaks) {
125    TestEventListeners& listeners = UnitTest::GetInstance()->listeners();
126
127    // Adds the leak checker to the end of the test event listener list,
128    // after the default text output printer and the default XML report
129    // generator.
130    //
131    // The order is important - it ensures that failures generated in the
132    // leak checker's OnTestEnd() method are processed by the text and XML
133    // printers *before* their OnTestEnd() methods are called, such that
134    // they are attributed to the right test. Remember that a listener
135    // receives an OnXyzStart event *after* listeners preceding it in the
136    // list received that event, and receives an OnXyzEnd event *before*
137    // listeners preceding it.
138    //
139    // We don't need to worry about deleting the new listener later, as
140    // Google Test will do it.
141    listeners.Append(new LeakChecker);
142  }
143  return RUN_ALL_TESTS();
144}
145