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28 //
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
39 using ::testing::EmptyTestEventListener;
40 using ::testing::InitGoogleTest;
41 using ::testing::Test;
42 using ::testing::TestCase;
43 using ::testing::TestEventListeners;
44 using ::testing::TestInfo;
45 using ::testing::TestPartResult;
46 using ::testing::UnitTest;
47
48 namespace {
49
50 // We will track memory used by this class.
51 class Water {
52 public:
53 // Normal Water declarations go here.
54
55 // operator new and operator delete help us control water allocation.
operator new(size_t allocation_size)56 void* operator new(size_t allocation_size) {
57 allocated_++;
58 return malloc(allocation_size);
59 }
60
operator delete(void * block,size_t)61 void operator delete(void* block, size_t /* allocation_size */) {
62 allocated_--;
63 free(block);
64 }
65
allocated()66 static int allocated() { return allocated_; }
67
68 private:
69 static int allocated_;
70 };
71
72 int 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.
78 class LeakChecker : public EmptyTestEventListener {
79 private:
80 // Called before a test starts.
OnTestStart(const TestInfo &)81 virtual void OnTestStart(const TestInfo& /* test_info */) {
82 initially_allocated_ = Water::allocated();
83 }
84
85 // Called after a test ends.
OnTestEnd(const TestInfo &)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
TEST(ListenersTest,DoesNotLeak)98 TEST(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.
TEST(ListenersTest,LeaksWater)105 TEST(ListenersTest, LeaksWater) {
106 Water* water = new Water;
107 EXPECT_TRUE(water != NULL);
108 }
109
110 } // namespace
111
main(int argc,char ** argv)112 int 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