Google Test and Code Coverage

Nailing down the fundamentals:

Compile testapp

$ make testapp
g++ -isystem include -g -Wall -Wextra -pthread -c sample1.cc
g++ -isystem include -Igooglemock -Igooglemock/include -g -Wall -Wextra -pthread -c googlemock/src/gmock-all.cc
g++ -isystem include -I. -g -Wall -Wextra -pthread -c src/gtest-all.cc
ar rv gmock.a gmock-all.o gtest-all.o
ar: creating gmock.a
a - gmock-all.o
a - gtest-all.o
g++ -isystem include -g -Wall -Wextra -pthread sample1.o testapp.cc gmock.a -o testapp

Run testapp

$ ./testapp
Running main() from testapp.cc
[==========] Running 6 tests from 2 test cases.
[----------] Global test environment set-up.
[----------] 3 tests from FactorialTest
[ RUN      ] FactorialTest.Negative
[       OK ] FactorialTest.Negative (0 ms)
[ RUN      ] FactorialTest.Zero
[       OK ] FactorialTest.Zero (0 ms)
[ RUN      ] FactorialTest.Positive
[       OK ] FactorialTest.Positive (0 ms)
[----------] 3 tests from FactorialTest (0 ms total)

[----------] 3 tests from IsPrimeTest
[ RUN      ] IsPrimeTest.Negative
[       OK ] IsPrimeTest.Negative (0 ms)
[ RUN      ] IsPrimeTest.Trivial
[       OK ] IsPrimeTest.Trivial (0 ms)
[ RUN      ] IsPrimeTest.Positive
[       OK ] IsPrimeTest.Positive (0 ms)
[----------] 3 tests from IsPrimeTest (0 ms total)

[----------] Global test environment tear-down
[==========] 6 tests from 2 test cases ran. (0 ms total)
[  PASSED  ] 6 tests.

Some Explanations

The testapp.cc has the main() entry point and the sample1.cc contains the critical algorithms to be tested. Therefore, the executable testapp is the stopshop opportunity to statically link gmock.a into itself as well as the sample1.o binary to be tested. In summary, testapp has the following core meat ingredients:

- testapp.cc
- sample1.cc
- gmock.a (has all of the Google Test stuff)

In the Makefile, the gmock.a is the static binary artifact that has all (gmock and gtest) of the Google Test stuff. Here is why:

# combines both gtest and gmock into one static library. gmock.a is the entire Google Test stuff
gmock.a : gmock-all.o gtest-all.o
    $(AR) $(ARFLAGS) $@ $^

gtest-all.o : src/*.cc src/*.h include/gtest/*.h include/gtest/internal/*.h
    $(CXX) $(CPPFLAGS) -I. $(CXXFLAGS) -c src/gtest-all.cc

gmock-all.o : googlemock/src/*.cc googlemock/include/gmock/*.h googlemock/include/gmock/internal/*.h
    $(CXX) $(CPPFLAGS) -Igooglemock -Igooglemock/include $(CXXFLAGS) -c googlemock/src/gmock-all.cc

How to Get Code Coverage

This line in Makefile is for code coverage:

-lgcov -fprofile-arcs -ftest-coverage

To get code coverage steps:

- make testapp
- ./getcoverage.sh
- cd CODE_COVERAGE/ && python -m SimpleHTTPServer

Points to Ponder

Compilation step only produces *.gcno. Running the testapp executable producest *.gcda. Running gcov testapp.gcno produces *.gcov files. Then running lcov --capture --directory . --output-file gcov_result.info produces the gcov_result.info file. Finally, genhtml gcov_result.info --output-directory outputdir/ produces html files showing the coverage result percentage.

Nix Way

With the provided shell.nix, the gcov, lcov and python 2.7 will be accessible by:

nix-shell