Coverage

Pytest · Reference cheat sheet

📋 Overview

pytest-cov integrates coverage.py: measure line/branch coverage, fail under thresholds, and emit terminal/HTML/XML reports for CI.

🔧 Core concepts

Run from project root so paths resolve correctly.

💡 Examples

CLI:

pytest --cov=myapp --cov-report=term-missing
pytest --cov=myapp --cov-report=html --cov-report=xml
pytest --cov=myapp --cov-fail-under=85 --cov-branch

pyproject.toml:

[tool.coverage.run]
source = ["myapp"]
branch = true
omit = ["*/tests/*", "*/migrations/*"]

[tool.coverage.report]
show_missing = true
skip_covered = false
fail_under = 85

[tool.pytest.ini_options]
addopts = "--cov=myapp --cov-report=term-missing"

HTML: open htmlcov/index.html.

CI: publish coverage.xml to Codecov/Sonar; keep thresholds realistic for new projects.

⚠️ Pitfalls

• Measuring tests or virtualenv paths — set source/omit.
• 100% line coverage with zero meaningful assertions.
• Combining xdist without pytest-cov concurrency support configured.
• Dynamic imports / # pragma: no cover abused to hide gaps.
• Different coverage between local and CI due to optional extras.

🔗 Related

• Install
• CLI
• Configuration
• xdist
• Plugins
• Asserts