Provides an overview of how to use code coverage tools when running the unit tests in the EC codebase.

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Code coverage is only available for host-based unit tests, as opposed to manual tests that run on target hardware.

To build host-based unit tests for code coverage, invoke make with the coverage target, as follows:

make coverage -j

This target will compile and link the unit tests with --coverage flag (which pulls in the gcov libraries), run the tests, and then process the profiling data into a code coverage report using the lcov and genhtml tools.

The coverage report top-level page is build/coverage/coverage_rpt/index.html.

When building for code coverage, you may see multiple warnings of the form geninfo: WARNING: no data found for /mnt/host/source/src/platform/ec/core/host/cpu.h and genhtml: WARNING: function data mismatch at /mnt/host/source/src/platform/ec/common/math_util.c:134

These warnings can be ignored. (FYI, the "function data mismatch" warnings appear to be caused in part by using relative paths instead of absolute paths.)

To build the Zephyr unit tests for code coverage run:

zmake test --host-tests-only --coverage genhtml -q -o build/zephyr/coverage_rpt/ build/zephyr/all_tests.info

The coverage report top-level page is build/zephyr/coverage_rpt/index.html.

However you probably want to merge that with a single board's coverage report also, so that you can include code that is not part of any test as well.

zmake build --coverage herobrine
zmake test --host-tests-only --coverage
genhtml -q -s --branch-coverage -o build/zephyr/coverage_rpt/ \
  build/zephyr/all_tests.info build/zephyr/herobrine/output/zephyr.info

The coverage report top-level page is build/zephyr/coverage_rpt/index.html.

For coverage report for a single test you can run: zmake test --coverage <TESTNAME>

Example: zmake test --coverage test-drivers genhtml -q -o build/zephyr/test-drivers/output/coverage_rpt/ build/zephyr/test-drivers/output/zephyr.info