Hi, Alan
Thanks for making it clear. But I was more confused now 
I tested on a simple program and used both gcov and lcov to get branch coverage.
The code and build commands as below:
Example simple.cc
#include
// If not comment this line, the branch coverage won’t reach to 100%
// #include
int main(int argc, const char* argv) {
std::string str = “foo”;
str = argv[1];
if (str == “foo” || str == “bar”) {
int a = 5;
a = 7;
} else {
int b = 6;
b = 4;
}
return 0;
}
Coverage build commands
#!/bin/bash
g++ -o simple -fno-exceptions -fno-inline -fprofile-arcs -ftest-coverage simple.cc
./simple “foo”
./simple “bar”
./simple “hello1”
./simple “hello2”
./simple “hello3”
./simple “hello4”
./simple “hello5”
./simple “hello6”
./simple “hello7”
./simple “hello8”
lcov --rc lcov_branch_coverage=1 --capture --directory . --output-file simple.lcov.info
genhtml simple.lcov.info --function-coverage --branch-coverage --output-directory lcov_out/
gcov -b -c simple.gcno
Both gcov and lcov will give a 100% branch coverage report:
My questions:
- What’s the “official” evaluation formula on branch coverage?
Sorry I can’t find any compelling documents to describe the accurate algorithm on this issue.
I just thought gcov/lcov won’t consider how many times the decision evaluated to False.
Please see the gcov file on my example: simple.cc. There are 6 branches in total which are all hit
So the result would be 6/6 * 100% = 100%
- Are there any existing post-processing tools based on clang/llvm source based coverage?
I just saw a clion plugin at github which may generate branch coverage by using region coverage data. But this depends on clion
which is not easy to implement automation test.
- How to disable STL (or other) noise in gcov branch coverage?
Sorry, this is not clang/llvm question. But I am still looking forward to some suggestions. For example, if I add iostream header back to
simple.cc, then we won’t get a 100% branch coverage. This may because iostream will introduce some global destruction branch.
Or if it’s impossible, can we think clang region coverage should be a best practice in C++ testing world??
AFAIK, chromium is using region coverage now.
FYI.
Thanks,
Ted Xie
Phipps, Alan <a-phipps@ti.com> 于2020年5月4日周一 上午12:54写道：