How to get Bazel code coverage summary for C++?

Question

I have a small setup using of a static library and executable doing unit tests. when running bazel coverage it creates a coverage.dat file inside the test log folder of the unit test binary. The result is either lcov file or llvm profdata file. The coverage data generator from Bazel seems to be able to distinguish between Clang and GCC, but there seems to be no way the generate a report.

Is there an way to get some statistics from the coverage generator?

Answer 1

I do bazel coverage this way:

  bazel coverage -s \                                         
    --instrument_test_targets \
    --experimental_cc_coverage \
    --combined_report=lcov \
    --coverage_report_generator=@bazel_tools//tools/test/CoverageOutputGenerator/java/com/google/devtools/coverageoutputgenerator:Main \
    //...

And then I generate an HTML Output this way.

  genhtml /home/user1/.cache/bazel/_bazel_user1/e74a825d0eb0c2db4b6f8afd819b274c/execroot/__main__/bazel-out/k8-fastbuild/testlogs/foo_test/coverage.dat --output-directory coverage

Answer 2

bazel version: 3.7.0

bazelisk coverage  -s  \
                   --combined_report=lcov  \
                   --experimental_cc_coverage \
                   --instrumentation_filter="//Src[/:]"  \
                   --local_test_jobs=1  \
                   --nocache_test_results 
                   //tests:all

then run cmd:

genhtml bazel-out/_coverage/_coverage_report.dat  \
        --highlight \
        --legend \
        --output-directory coverage

the result got as below:

  ......
  Overall coverage rate:
  lines......: 68.7% (3076 of 4480 lines)
  functions..: 61.5% (638 of 1037 functions)