Code coverage is an important requirement for our unit test project, here we will introduce the step briefly. We will take libaom as an example.

1. compile:

   1. using gcc and g++: cmake ../aom_mod/ -DCMAKE_C_COMPILER=/usr/bin/gcc -DCMAKE_CXX_COMPILER=/usr/bin/g++
   2. add following flags -fprofile-arcs -ftest-coverage
   3. add link flags: -fprofile-arcs -ftest-coverage
   4. build debug mode
   5. total command:

   cmake ../aom_mod/ -DCMAKE_C_COMPILER=/usr/bin/gcc
      -DCMAKE_CXX_COMPILER=/usr/bin/g++ 
      '-DAOM_EXTRA_C_FLAGS=-fprofile-arcs -ftest-coverage' 
      '-DAOM_EXTRA_CXX_FLAGS=-fprofile-arcs -ftest-coverage' 
      '-DAOM_EXTRA_EXE_LINKER_FLAGS=-fprofile-arcs -ftest-coverage' -DCMAKE_BUILD_TYPE=Debug

   7. check the files generated: find name with suffix gcno or gcda, usually they are generated in the same folder with obj files.

2. clean up from previous run

$ lcov --zerocounters --directory .

3. create baseline

$ lcov --no-external --capture --initial --base-directory ../aom_mode --directory . --output-file
   libaom_base.info

4. run test

$ ./test --gtest_filter="test.*"

5. run lcov again after tests

$ lcov --no-external --capture --base-directory ../aom_mode
   --directory . --output-file libaom_test.info

6. combine lcove tracefiles

$ lcov --add-tracefile ./libaom_base.info --add-tracefile
   ./libaom_test.info --output-file ./libaom_total.info

7. remove/filter out remaining unwanted stuff

$ lcov -r libaom_total.info "*third_party*" -o
   libaom_total_reduced.info

8. Generate html

$ genhtml decoder.info --output-directory ./

9. Generate report for jenkins Install lcov_cobertura.py

$ pip install lcov_cobertura.py

Find where is lcov_cobertura, open python console

In [0]: import lcov_cobertura
In [1]: lcov_cobertura.__file__ # will output the location of lcov_cobertura.pyc

create cobertura report:

$ python /home/wenyao/.local/lib/python2.7/site-packages/lcov_cobertura.pyc ./libaom_total_slim.info -b ../aom_mod -o coverage.xml

1. Issue: gcov expect "xxx.o" while cmake produce "xxx.c.o" Fix: add CMake flag, like: cmake -DCMAKE_C_OUTPUT_EXTENSION_REPLACE=1 -DCMAKE_CXX_OUTPUT_EXTENSION_REPLACE=1

1. https://wiki.documentfoundation.org/Development/Lcov
2. https://qiaomuf.wordpress.com/2011/05/26/use-gcov-and-lcov-to-know-your-test-coverage/
3. https://medium.com/@kelvin_sp/generating-code-coverage-with-qt-5-and-gcov-on-mac-os-4999857f4676
4. https://manpages.debian.org/unstable/lcov/lcov.1.en.html