qa-pytest-writer

name	qa-pytest-writer
description	Generate pytest unit and integration tests for Python with fixtures, parametrize, markers, conftest patterns, and plugin ecosystem support.
output_dir	tests/unit

QA Pytest Writer

Purpose

Write pytest unit and integration tests from test case specifications. Transform structured test cases (from qa-testcase-from-docs, qa-manual-test-designer, or specs) into executable pytest code with fixtures, parametrization, markers, and conftest patterns.

Trigger Phrases

• "Write pytest tests for [module/function]"
• "Generate pytest unit tests from test cases"
• "Create pytest integration tests"
• "Add pytest tests with fixtures for [feature]"
• "Pytest parametrized tests for [function]"
• "Pytest tests with conftest fixtures"
• "Pytest async tests for [API handler]"
• "Pytest tests with mocking (monkeypatch/patch)"

Key Features

Feature	Description
Fixtures	Scope: function, class, module, session; autouse, yield for teardown
@pytest.mark.parametrize	Data-driven tests with multiple input/output sets
Markers	skip, skipif, xfail, custom markers for categorization
conftest.py	Shared fixtures across test modules/directories
Plugin ecosystem	pytest-cov, pytest-xdist, pytest-asyncio, pytest-html, pytest-factoryboy
Assertion introspection	Rich failure output; plain assert statements

Workflow

1. Read test cases — From specs, requirements, or manual test designs
2. Analyze Python code — Inspect module under test: functions, classes, dependencies
3. Generate test files — Produce test_{module}.py with test functions
4. Add fixtures/conftest — Shared setup, teardown, parametrization
5. Run — User runs pytest to execute tests

Context7 MCP

Use Context7 MCP for current pytest documentation when:

• Fixture scope or parametrize syntax is uncertain
• Plugin APIs (pytest-asyncio, pytest-cov) need verification
• Marker or configuration options require up-to-date reference

Key Patterns

Pattern	Usage
test_ prefix	Test functions: def test_something():
assert	Plain assertions; no special API needed
Fixtures	def fixture_name(): with scope, autouse, yield
@pytest.mark.parametrize	Data-driven tests
Markers	@pytest.mark.skip, @pytest.mark.skipif, @pytest.mark.xfail
conftest.py	Shared fixtures in package/directory
monkeypatch	Built-in for patching attributes/env
tmp_path	Built-in temporary directory fixture
unittest.mock	patch, MagicMock for mocking

Mocking

Approach	Use Case
unittest.mock.patch	Patch modules, classes, functions
unittest.mock.MagicMock	Create mock objects with configurable behavior
pytest-mock (mocker)	mocker fixture wraps patch; cleaner syntax
monkeypatch	Built-in; patch attributes, env vars, sys.path

Configuration

• pytest.ini — Legacy config (markers, addopts, testpaths)
• pyproject.toml — Modern config under [tool.pytest.ini_options]
• conftest.py — Fixtures, hooks, plugin config

See references/config.md for configuration patterns.

Plugin Recommendations

Plugin	Purpose
pytest-cov	Code coverage reporting
pytest-xdist	Parallel test execution
pytest-asyncio	Async test support
pytest-html	HTML test reports
pytest-factoryboy	Factory fixtures for models

File Naming

• test_{module}.py — Preferred (e.g., test_calculator.py)
• Place in tests/ or colocated with source per project convention

Scope

Can do (autonomous):

• Generate pytest unit and integration tests from test case specs
• Add fixtures (function/class/module/session scope), conftest.py
• Use @pytest.mark.parametrize for data-driven tests
• Apply markers (skip, skipif, xfail, custom)
• Mock with patch, MagicMock, monkeypatch, pytest-mock
• Configure pytest.ini / pyproject.toml
• Call qa-diagram-generator for test flow diagrams if needed

Cannot do (requires confirmation):

• Change production code to satisfy tests
• Add tests for requirements not in source documents
• Override project-level pytest config without approval

Will not do (out of scope):

• Execute tests (user runs pytest)
• Write Playwright/Selenium E2E tests (use qa-playwright-ts-writer or Python E2E skills)
• Modify CI/CD pipelines

References

• references/patterns.md — Fixtures, parametrize, conftest, async testing, mocking
• references/assertions.md — Assertion patterns: comparison, exceptions, warnings, approximate
• references/config.md — pyproject.toml, pytest.ini, conftest.py, markers, plugins
• references/best-practices.md — Fixture scope, naming, organization, test isolation, coverage

Quality Checklist

• Tests match test case steps and expected results
• Fixtures are properly scoped (function vs session)
• No hardcoded secrets or sensitive data
• Assertions are specific (avoid only truthiness where value matters)
• Teardown via yield in fixtures where resources need cleanup
• File naming follows test_{module}.py convention
• Parametrize used for data-driven cases; markers for categorization
• Coverage targets considered if specified in requirements

Troubleshooting

Symptom	Likely Cause	Fix
Fixture not found	Scope or conftest location	Ensure conftest.py in same dir or parent; check fixture scope
Parametrize id collision	Duplicate ids	Use ids parameter for unique test names
Tests pass individually, fail together	Shared mutable state	Use function-scoped fixtures; avoid module/session for mutable data
monkeypatch not persisting	Wrong target path	Patch where object is used (e.g., mymodule.func not builtins.func)
Async tests fail	Missing pytest-asyncio	Add @pytest.mark.asyncio; install pytest-asyncio
Coverage not collected	Plugin not configured	Add pytest-cov; run pytest --cov=src
Import errors in tests	Path/sys.path	Add conftest.py with sys.path or use pyproject.toml pythonpath