Compatibility¶

rpytest aims to be a drop-in replacement for pytest. This document details compatibility status and known differences.

pytest Compatibility¶

Supported Features¶

Feature	Status	Notes
Test discovery	Full	`test_.py`, `Test` classes
Assertions	Full	Native pytest assertions
Fixtures	Full	All scopes supported
Markers	Full	`@pytest.mark.*`
Parametrization	Full	`@pytest.mark.parametrize`
conftest.py	Full	Hierarchical fixtures
CLI arguments	Partial	Common flags supported
Plugins	Full	Via pytest execution
Hooks	Partial	Common hooks

CLI Compatibility¶

Supported pytest flags:

# Test selection
rpytest tests/                    # Path
rpytest tests/test_api.py         # File
rpytest tests/test_api.py::test_x # Node ID
rpytest -k "auth"                 # Keyword
rpytest -m "not slow"             # Marker

# Output
rpytest -v                        # Verbose
rpytest -vv                       # Very verbose
rpytest -q                        # Quiet
rpytest --tb=short                # Traceback style

# Execution
rpytest -x                        # Stop on first failure
rpytest --lf                      # Last failed
rpytest --ff                      # Failed first
rpytest -n 4                      # Parallel workers

# Collection
rpytest --collect-only            # List tests
rpytest --co                      # Short form

# Configuration
rpytest -c pytest.ini             # Config file
rpytest -o "key=value"            # Override option

Unsupported/Different Flags¶

Flag	Status	Alternative
`--dist`	Not needed	Use `--shard`
`--boxed`	Not supported	Default isolation
`--forked`	Not supported	Use subprocess workers
`--cov`	Plugin-based	Use pytest directly

Python Version Support¶

Version	Status
Python 3.8	Supported
Python 3.9	Supported
Python 3.10	Supported
Python 3.11	Supported
Python 3.12	Supported
Python 3.13	Supported

pytest Version Support¶

Version	Status
pytest 7.0+	Full support
pytest 8.0+	Full support
pytest 9.0+	Full support

Plugin Compatibility¶

Fully Compatible¶

These plugins work without modification:

pytest-mock
pytest-asyncio
pytest-django
pytest-flask
pytest-factoryboy
pytest-freezegun
pytest-timeout
pytest-env

Partially Compatible¶

These plugins work but may have limitations:

Plugin	Notes
pytest-xdist	Use rpytest's native `-n` instead
pytest-cov	Use directly with pytest
pytest-html	Report generation may differ
pytest-sugar	Terminal output different

Not Recommended¶

Plugin	Reason
pytest-parallel	Conflicts with rpytest parallelism
pytest-randomly	Seed handling may differ

Feature Parity¶

Markers¶

# All standard markers work
@pytest.mark.skip
@pytest.mark.skipif
@pytest.mark.xfail
@pytest.mark.parametrize
@pytest.mark.usefixtures

# Custom markers
@pytest.mark.slow
@pytest.mark.integration

Fixtures¶

# All scopes
@pytest.fixture(scope="function")
@pytest.fixture(scope="class")
@pytest.fixture(scope="module")
@pytest.fixture(scope="package")
@pytest.fixture(scope="session")

# Autouse
@pytest.fixture(autouse=True)

# Parametrized fixtures
@pytest.fixture(params=[1, 2, 3])

Parametrization¶

# Simple
@pytest.mark.parametrize("x", [1, 2, 3])

# Multiple parameters
@pytest.mark.parametrize("x,y", [(1, 2), (3, 4)])

# Nested
@pytest.mark.parametrize("x", [1, 2])
@pytest.mark.parametrize("y", ["a", "b"])

# IDs
@pytest.mark.parametrize("x", [1, 2], ids=["one", "two"])

Hooks¶

Supported hooks:

# conftest.py

def pytest_configure(config):
    """Modify configuration."""
    pass

def pytest_collection_modifyitems(items):
    """Modify collected tests."""
    pass

def pytest_runtest_setup(item):
    """Called before test setup."""
    pass

def pytest_runtest_teardown(item):
    """Called after test teardown."""
    pass

Verification¶

Drop-in Verification¶

Verify rpytest matches pytest behavior:

rpytest --verify-dropin tests/

This runs tests with both rpytest and pytest and compares results.

Output Comparison¶

# Generate pytest results
pytest tests/ --junitxml=pytest-results.xml

# Generate rpytest results
rpytest tests/ --junitxml=rpytest-results.xml

# Compare
diff pytest-results.xml rpytest-results.xml

Known Differences¶

Output Format¶

rpytest output differs slightly from pytest:

# pytest
test_api.py::test_login PASSED

# rpytest
tests/test_api.py::test_login ✓

Collection Order¶

Test collection order may differ: - pytest: Import order - rpytest: Filesystem order (faster)

Fixture Timing¶

With --reuse-fixtures, session fixtures persist: - pytest: Recreated each run - rpytest: Reused across runs

Error Messages¶

Stack traces may have slight formatting differences.

Migration Guide¶

From pytest¶

Replace pytest with rpytest:

# Before
pytest tests/ -v

# After
rpytest tests/ -v

Replace pytest-xdist with native parallelism:

# Before
pytest tests/ -n 4

# After
rpytest tests/ -n 4

Verify compatibility:
```
rpytest --verify-dropin tests/
```

CI/CD Migration¶

# Before
- run: pip install pytest pytest-xdist
- run: pytest tests/ -n auto

# After
- run: pip install rpytest
- run: rpytest tests/ -n auto

Mixed Usage¶

Run both for comparison:

# Development: rpytest for speed
rpytest tests/ --watch

# CI: pytest for coverage
pytest tests/ --cov

Reporting Issues¶

If you find compatibility issues:

Check this document for known differences
Try with pytest to confirm different behavior
Report at https://github.com/anthropics/rpytest/issues

Include: - pytest version - rpytest version - Minimal reproduction - Expected vs actual behavior