Memory leak when using Google Test on Windows

Question

When I run the following code:

#include "gmock/gmock.h"
#include "gtest/gtest.h"

#define _CRTDBG_MAP_ALLOC
#include <crtdbg.h>

int main(int argc, char **argv) 
{
    ::testing::InitGoogleTest(&argc, argv);
    _CrtDumpMemoryLeaks();
    return 0;
}

I get the following output:

Detected memory leaks!
Dumping objects ->
{652} normal block at 0x00074CE0, 4 bytes long.
 Data: < L  > 98 4C 07 00 
{651} normal block at 0x00074C98, 12 bytes long.
 Data: <,           > 2C 03 1B 01 00 00 00 00 00 00 00 00 
{650} normal block at 0x00074C50, 8 bytes long.
 Data: <hI      > 68 49 07 00 00 00 00 00 
{649} normal block at 0x00074C10, 4 bytes long.
 Data: <t   > 74 03 1B 01 
{648} normal block at 0x00074BC8, 8 bytes long.
 Data: <xK      > 78 4B 07 00 00 00 00 00 
{647} normal block at 0x00074B70, 28 bytes long.
 Data: <         K   L  > BC 01 1B 01 01 CD CD CD C8 4B 07 00 E0 4C 07 00 
{646} normal block at 0x00074B28, 8 bytes long.
 Data: < I      > 18 49 07 00 00 00 00 00 
{645} normal block at 0x00074AE0, 8 bytes long.
 Data: < I      > 04 49 07 00 00 00 00 00 
{644} normal block at 0x00074A98, 8 bytes long.
 Data: < H      > DC 48 07 00 00 00 00 00 
{643} normal block at 0x00074A50, 8 bytes long.
 Data: < H      > C8 48 07 00 00 00 00 00 
{642} normal block at 0x00074A08, 8 bytes long.
 Data: < H      > B4 48 07 00 00 00 00 00 
{641} normal block at 0x000749C0, 8 bytes long.
 Data: < H      > A0 48 07 00 00 00 00 00 
{640} normal block at 0x00074E90, 1 bytes long.
 Data: < > 00 
{639} normal block at 0x00074870, 272 bytes long.
 Data: <        t    N  > 20 03 1B 01 CD CD CD CD 74 FA 1B 01 90 4E 07 00 
{638} normal block at 0x00074F68, 72 bytes long.
 Data: <C:\Users\Baz> 43 3A 5C 55 73 65 72 73 5C 45 42 41 52 47 52 49 
{637} normal block at 0x00074E48, 8 bytes long.
 Data: <hO  G   > 68 4F 07 00 47 00 00 00 
{616} normal block at 0x00074EE0, 72 bytes long.
 Data: <C:\Users\Baz> 43 3A 5C 55 73 65 72 73 5C 45 42 41 52 47 52 49 
{595} normal block at 0x00074828, 8 bytes long.
 Data: <        > F0 F9 1B 01 00 00 00 00 
{594} normal block at 0x000747E8, 1 bytes long.
 Data: < > 00 
{561} normal block at 0x000747A0, 5 bytes long.
 Data: <fast > 66 61 73 74 00 
{496} normal block at 0x00074760, 1 bytes long.
 Data: < > 00 
{311} normal block at 0x00074720, 1 bytes long.
 Data: < > 00 
{282} normal block at 0x000746E0, 2 bytes long.
 Data: <* > 2A 00 
{253} normal block at 0x00074698, 5 bytes long.
 Data: <auto > 61 75 74 6F 00 
Object dump complete.

What am I doing wrong?

Answer 1

Adding to the accepted answer, the Google documentation states:

Since the statically initialized Google Test singleton requires allocations on the heap, the Visual C++ memory leak detector will report memory leaks at the end of the program run. The easiest way to avoid this is to use the _CrtMemCheckpoint and _CrtMemDumpAllObjectsSince calls to not report any statically initialized heap objects. See MSDN for more details and additional heap check/debug routines.

This involves calling _CrtMemCheckPoint just after ::testing::InitGoogleTest and then calling _CrtMemDumpAllObjectsSince after RUN_ALL_TESTS(). The main function looks a bit like this:

::testing::InitGoogleTest(&argc, &argv);
// Get a checkpoint of the memory after Google Test has been initialized.
_CrtMemState memoryState = {0};
_CrtMemCheckpoint( &memoryState );
int retval = RUN_ALL_TESTS();

// Check for leaks after tests have run
_CrtMemDumpAllObjectsSince( &memoryState );
return retval;

Unfortunately, if a test fails Google test causes a memory leak, which means this isn't a perfect solution.

Answer 2

You're not doing anything wrong. The 'memory leaks' come from heap allocations of the statically initialized google test singleton class.

Here's the answer from google tests FAQ: How do I suppress the memory leak messages on Windows?