How to Perform C Code Coverage Testing with gcov and lcov on Ubuntu

Background : In recommendation system testing, code coverage is a key metric for assessing test completeness, especially for C code. This guide shows how to measure C code coverage using gcov and lcov on Ubuntu.

Environment preparation : Install the required tools on Ubuntu:

sudo apt-get install gcov

sudo apt-get install lcov

Verify installation with gcov -v and lcov -v .

Simple example : Write a basic C++ program (shown in the original images) and compile it with coverage flags -ftest-coverage and -fprofile-arcs . After compilation, the presence of test.gcno indicates successful instrumentation.

Generating the executable : Link the object files to produce the binary. Running the binary creates .gcda files, which contain execution counts for each line.

Generating test results : Use lcov to capture coverage data and produce an HTML report:

lcov -c -d . -o coverage.info

genhtml coverage.info -o coverage_report

The HTML report visualizes covered (blue) and uncovered (red) lines, showing execution counts and highlighting missed lines with ##### .

Coverage metrics : The report displays line coverage (e.g., 53.8%) and function coverage (e.g., 40.00%), including the main function.

Conclusion : This tutorial demonstrated basic C code coverage testing with gcov and lcov. Future posts will cover coverage for shared libraries and external parameters. Stay tuned for more testing insights.