LCOV Tooling

Finding Coverage Gaps

# Run coverage first
make check-coverage

# Uncovered lines
grep "^DA:" reports/coverage/coverage.info | grep ",0$"

# Uncovered branches
grep "^BRDA:" reports/coverage/coverage.info | grep ",0$"

# Uncovered functions
grep "^FNDA:0," reports/coverage/coverage.info

coverage.info Format

SF:/path/to/file.c          # Source file
FN:42,function_name         # Function at line 42
FNDA:5,function_name        # Function called 5 times
DA:45,3                     # Line 45 executed 3 times
DA:46,0                     # Line 46 never executed (GAP!)
BRDA:50,0,0,2               # Line 50, block 0, branch 0, taken 2 times
BRDA:50,0,1,0               # Line 50, block 0, branch 1, never taken (GAP!)
end_of_record

Key patterns:

• DA:line,0

  = uncovered line

• BRDA:line,block,branch,0

  = uncovered branch

• FNDA:0,name

  = uncovered function

Coverage Files

make check-coverage

reports/coverage/coverage.info

reports/coverage/summary.txt

make check-coverage TEST=unit/foo

reports/coverage/unit/foo.coverage.info

.coverage.txt

Exclusion Markers

LCOV_EXCL_LINE

LCOV_EXCL_BR_LINE

LCOV_EXCL_START

LCOV_EXCL_STOP

Usage:

assert(ptr != NULL);                    // LCOV_EXCL_BR_LINE
if (!ptr) PANIC("Invariant violated");  // LCOV_EXCL_BR_LINE

Note: Markers are NOT reliably honored inside

static

See

coverage

Quick Workflow

# 1. Run coverage
make check-coverage

# 2. Check summary
cat reports/coverage/summary.txt

# 3. Find gaps in specific file
grep -A 1000 "SF:.*myfile.c" reports/coverage/coverage.info | \
  grep -m 1 -B 1000 "end_of_record" | grep ",0$"

Related Skills

• coverage

  - Policy (90% requirement, exclusion rules)

• testability

  - Refactoring patterns for gaps