Claude-skill-registry Bun Test Coverage

Use for test coverage with Bun, --coverage flag, lcov reports, thresholds, and CI integration.

install

source · Clone the upstream repo

git clone https://github.com/majiayu000/claude-skill-registry

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/majiayu000/claude-skill-registry "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/data/bun-test-coverage" ~/.claude/skills/majiayu000-claude-skill-registry-bun-test-coverage && rm -rf "$T"

manifest: skills/data/bun-test-coverage/SKILL.md

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 < 80%
bun test --coverage --coverage-threshold 80

# Per-metric thresholds in bunfig.toml

[test]
coverage = true
coverageThreshold = {
  lines = 80,
  functions = 75,
  branches = 70
}

Excluding Files

[test]
coverage = true

# Skip test files from coverage
coverageSkipTestFiles = true

# Patterns to exclude
coverageIgnore = [
  "**/*.test.ts",
  "**/fixtures/**",
  "**/mocks/**"
]

CI Integration

GitHub Actions

- name: Run tests with coverage
  run: bun test --coverage --coverage-reporter=lcov

- name: Upload coverage to Codecov
  uses: codecov/codecov-action@v5
  with:
    files: ./coverage/lcov.info

Output Directory

# Custom output directory
bun test --coverage --coverage-dir=./reports/coverage

Programmatic Coverage

import { test, expect } from "bun:test";

// Get coverage data programmatically
const coverage = Bun.coverage;

// Access after tests complete
process.on("exit", () => {
  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

Set realistic thresholds - Start at 60%, increase gradually
Exclude generated files - Mock files, type definitions
Focus on critical paths - Business logic over boilerplate
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