sample10_unittest.cc revision d0332953cda33fb4f8e24ebff9c49159b69c43d6 
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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_TRUE(difference <= 0)
93        << "Leaked " << difference << " unit(s) of Water!";
94  }
95
96  int initially_allocated_;
97};
98
99TEST(ListenersTest, DoesNotLeak) {
100  Water* water = new Water;
101  delete water;
102}
103
104// This should fail when the --check_for_leaks command line flag is
105// specified.
106TEST(ListenersTest, LeaksWater) {
107  Water* water = new Water;
108  EXPECT_TRUE(water != NULL);
109}
110
111}  // namespace
112
113int main(int argc, char **argv) {
114  InitGoogleTest(&argc, argv);
115
116  bool check_for_leaks = false;
117  if (argc > 1 && strcmp(argv[1], "--check_for_leaks") == 0 )
118    check_for_leaks = true;
119  else
120    printf("%s\n", "Run this program with --check_for_leaks to enable "
121           "custom leak checking in the tests.");
122
123  // If we are given the --check_for_leaks command line flag, installs the
124  // leak checker.
125  if (check_for_leaks) {
126    TestEventListeners& listeners = UnitTest::GetInstance()->listeners();
127
128    // Adds the leak checker to the end of the test event listener list,
129    // after the default text output printer and the default XML report
130    // generator.
131    //
132    // The order is important - it ensures that failures generated in the
133    // leak checker's OnTestEnd() method are processed by the text and XML
134    // printers *before* their OnTestEnd() methods are called, such that
135    // they are attributed to the right test. Remember that a listener
136    // receives an OnXyzStart event *after* listeners preceding it in the
137    // list received that event, and receives an OnXyzEnd event *before*
138    // listeners preceding it.
139    //
140    // We don't need to worry about deleting the new listener later, as
141    // Google Test will do it.
142    listeners.Append(new LeakChecker);
143  }
144  return RUN_ALL_TESTS();
145}
146