Bun Test Coverage

Covers everything you need for test coverage in Bun without pulling in Istanbul or nyc. You get the coverage flag, lcov output for CI tools like Codecov, configurable thresholds that'll fail your builds, and patterns to exclude test files or fixtures. The bunfig.toml setup is straightforward, and the GitHub Actions example shows exactly how to pipe coverage reports where they need to go. Honestly the built-in reporter is clear enough that you might not need external dashboards for smaller projects. Good reference when you're setting coverage requirements or need to debug why certain files aren't showing up in reports.

skills.sh installs: 337
GitHub stars: 248
last updated: Aug 21, 2026

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Install

$ npx -y skills add secondsky/claude-skills --skill bun-test-coverage --agent claude-code

Installs into .claude/skills of the current project.

Files

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