gcov - how to reset the coverage statistics in the C/C++ code - googletest

Question

This question is related to googletest - command line option to execute "the first, the second, etc"
I want to be able to attribute given coverage results to each googletest test case.
QUESTION
In my C++ code, is it possible to reset the statistics?
Every time a test-case is done executing, I would save the accumulated gcov statistics and reset them.

Answer 1

From within your C++ code you could try it with __gcov_dump and __gcov_reset. They are mentioned in the GNU documentation although there is surprisingly limited info on them.
Below is a C++ program main.cpp that calls both.
1 #include <iostream>
2 #include <signal.h>
3
4 extern "C" void __gcov_dump(void);
5 extern "C" void __gcov_reset(void);
6
7
8 static void handler(int signum)
9 {
10 std::cout<<std::endl<<"Signal "<<signum<<" received!"<<std::endl;
11 __gcov_dump(); // Dump coverage upon interupt
12 std::cout<<"Coverage data dumped!"<<std::endl;
13 exit(0);
14 }
15
16
17 int main()
18 {
19 // Initialize signal handling
20 struct sigaction sa;
21
22 sa.sa_handler = handler;
23 sigemptyset(&sa.sa_mask);
24 sa.sa_flags = SA_RESTART;
25
26 if (sigaction(SIGINT, &sa, NULL) == -1)
27 std::cerr<<"ERROR: Could not register handler"<<std::endl;
28
29 // Main loop
30 while(true) {
31 int n;
32 std::cout<<"Type a number: ";
33 std::cin>>n;
34
35 if (n % 2 == 0) {
36 std::cout<<"Your number is even!"<<std::endl;
37 }
38 else {
39 std::cout<<"Your number is odd!"<<std::endl;
40 }
41 __gcov_reset(); // Reset coverage at the end of every iteration
42 }
43 }
If I compile it with g++ main.cpp --coverage -O0 and then run it as follows:
gomfy:gcov$ ./a.out
Type a number: 1
Your number is odd!
Type a number: 2
Your number is even!
Type a number: 3
Your number is odd!
Type a number: 4
Your number is even!
Type a number: ^C
Signal 2 received!
Coverage data dumped!
And then call gcovr in the build directory, I get:
gomfy:gcov$ gcovr
------------------------------------------------------------------------------
GCC Code Coverage Report
Directory: .
------------------------------------------------------------------------------
File Lines Exec Cover Missing
------------------------------------------------------------------------------
main.cpp 18 6 33% 12-13,17,22-24,26-27,35-36,39,41
------------------------------------------------------------------------------
TOTAL 18 6 33%
------------------------------------------------------------------------------
This shows that the coverage has been successfully reset at the end of the while loop.