Bun Test Coverage

Bun Test Coverage

Bun has built-in code coverage reporting without additional dependencies.

Enabling Coverage

# Enable coverage
bun test --coverage

# With threshold (fail if below)
bun test --coverage --coverage-threshold 80

Configuration in bunfig.toml

[test]
coverage = true
coverageThreshold = 0.8  # 80% minimum
coverageDir = "./coverage"

# Patterns to ignore
coverageSkipTestFiles = true

Coverage Output

------------------|---------|---------|-------------------
File              | % Funcs | % Lines | Uncovered Line #s
------------------|---------|---------|-------------------
All files         |   85.71 |   89.23 |
 src/index.ts     |  100.00 |  100.00 |
 src/utils.ts     |   75.00 |   82.35 | 23-25, 41-43
 src/api.ts       |   80.00 |   85.00 | 67, 89-92
------------------|---------|---------|-------------------

Coverage Reporters

# Default console output
bun test --coverage

# Generate lcov report
bun test --coverage --coverage-reporter=lcov

# Multiple reporters
bun test --coverage --coverage-reporter=text --coverage-reporter=lcov

Available Reporters

| Reporter | Output | |----------|--------| | text | Console table (default) | | lcov | coverage/lcov.info for CI tools | | json | coverage/coverage.json |

Coverage Thresholds

Set minimum coverage requirements:

# Fail if coverage  {
  console.log(coverage.getCoverageData());
});

Common Errors

| Error | Cause | Fix | |-------|-------|-----| | Coverage threshold not met | Coverage below threshold | Increase test coverage | | No coverage data | Files not executed | Check test includes file | | lcov not found | Missing reporter | Add --coverage-reporter=lcov |

Best Practices

1. Set realistic thresholds - Start at 60%, increase gradually
2. Exclude generated files - Mock files, type definitions
3. Focus on critical paths - Business logic over boilerplate
4. Run in CI - Prevent coverage regression

When to Load References

Load references/reporters.md when:

• Custom reporter configuration
• CI/CD integration details
• Codecov/Coveralls setup

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: secondsky
• Source: secondsky/claude-skills
• License: MIT

Install and usage instructions live in the source repository linked above.