Hands-On: Coverage Gap Analysis

"""Parse lcov coverage report and classify uncovered lines."""
import subprocess
import re
import json

def parse_lcov_gaps(info_file: str) -> list:
    """Extract uncovered lines from lcov .info file."""
    gaps = []
    current_file = None
    with open(info_file) as f:
        for line in f:
            if line.startswith("SF:"):
                current_file = line[3:].strip()
            elif line.startswith("DA:"):
                # DA:line_number,execution_count
                parts = line[3:].strip().split(",")
                line_no = int(parts[0])
                exec_count = int(parts[1])
                if exec_count == 0 and current_file:
                    # Skip stubs/ and test files
                    if "stubs/" not in current_file \
                    and "test" not in current_file:
                        gaps.append({
                            "file": current_file,
                            "line": line_no,
                            "classified": "unclassified",
                            "action": ""
                        })
    return gaps

gaps = parse_lcov_gaps("coverage.info")
print(f"Uncovered lines: {len(gaps)}")

# Save for manual classification
with open("gap_classification.json", "w") as f:
    json.dump(gaps, f, indent=2)
print("Edit gap_classification.json to classify each gap:")
print("  classified: missing_test | justified_exclusion | equivalent_mutant")
print("  action: add_test_TC_xxx | exclusion_rationale")