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name: test-coverage-analyst description: "Guides on analyzing and improving test coverage for Python (pytest-cov) and JavaScript (c8) projects. Use when a user asks to set up test coverage, generate coverage reports, understand why coverage is low, or improve their test coverage."

Test Coverage Analyst

Overview

This skill provides a structured workflow for analyzing and improving test coverage in Python and JavaScript projects. It covers configuration, report generation, and strategies for increasing coverage.

Workflow

Follow these steps to help a user with test coverage.

1. Identify Project Type and Tools

First, determine the project's language and package manager.

• Python: Look for requirements.txt, pyproject.toml, or a venv directory. The primary coverage tool is pytest-cov.
• JavaScript: Look for package.json. The recommended coverage tool is c8.

2. Check for Existing Configuration

Before adding new configurations, inspect existing files for coverage setup.

• For Python, check pyproject.toml, setup.cfg, or .coveragerc.
• For JavaScript, check the "c8" key or scripts in package.json, or a .nycrc.json file.

3. Configure and Install Tools

If coverage tools are not set up, guide the user through installation and configuration.

• For Python (pytest-cov):

  • Install pytest-cov.
  • Create or update the configuration, usually in pyproject.toml.
  • For detailed instructions, see Python Test Coverage with pytest-cov.

• For JavaScript (c8):

  • Install c8 as a dev dependency.
  • Create or update the configuration, usually in package.json.
  • For detailed instructions, see JavaScript Test Coverage with c8.

4. Run Coverage and Generate Reports

Execute the coverage tool to run tests and generate a report. The most useful reports are the terminal summary and the interactive HTML report.

• Terminal Report: Provides a quick summary of coverage percentages.
• HTML Report: Provides a detailed, line-by-line view of code coverage, which is essential for identifying untested code.
• XML/LCOV Report: These are for integrating with third-party CI services like Codecov.

Refer to the language-specific guides for exact commands.

5. Analyze the Report and Formulate a Strategy

• Interpret the results: Explain the difference between line and branch coverage. Use the HTML report to pinpoint exactly which lines and branches are not covered.
• Develop an improvement plan: Based on the report, create a plan to improve coverage.
• For a deep dive into analysis and strategies, consult the Test Coverage Improvement Strategies guide.

6. Continuous Integration (CI)

For ongoing coverage monitoring, help the user integrate coverage checks into their CI pipeline.

• This usually involves generating a report (XML or LCOV) and uploading it to a service like Codecov.
• For example configurations, see the CI Integration for Coverage guide.

Resources

This skill includes the following reference guides:

• references/python-pytest-cov.md: Detailed guide for pytest-cov.
• references/js-c8.md: Detailed guide for c8.
• references/ci-integration.md: Examples for integrating coverage in CI.
• references/improvement-strategies.md: In-depth strategies for improving test coverage.