pytest Cheatsheet¶

• Installation

Platform	Command
pip (All platforms)	INLINE_CODE_8
Ubuntu/Debian	INLINE_CODE_9
Fedora/RHEL	INLINE_CODE_10
Arch Linux	INLINE_CODE_11
macOS (Homebrew)	INLINE_CODE_12
Windows (Chocolatey)	INLINE_CODE_13
Virtual Environment	INLINE_CODE_14
With Common Plugins	INLINE_CODE_15
Verify Installation	INLINE_CODE_16

oder Grundlegende Befehle

Command	Description
INLINE_CODE_17	Run all tests in current directory and subdirectories
INLINE_CODE_18	Run tests in a specific file
INLINE_CODE_19	Run all tests in a specific directory
INLINE_CODE_20	Run a specific test function
INLINE_CODE_21	Run all tests in a specific class
INLINE_CODE_22	Run a specific test method in a class
INLINE_CODE_23	Run tests with verbose output (show test names)
INLINE_CODE_24	Run tests with very verbose output (show full details)
INLINE_CODE_25	Run tests in quiet mode (minimal output)
INLINE_CODE_26	Show print statements and stdout during test execution
INLINE_CODE_27	Stop after first test failure
INLINE_CODE_28	Stop after N test failures
INLINE_CODE_29	Run tests matching keyword expression
INLINE_CODE_30	Run tests matching multiple keywords (AND/NOT logic)
INLINE_CODE_31	Run tests marked with specific marker
INLINE_CODE_32	Run tests excluding specific marker
INLINE_CODE_33	Show which tests would be run without executing them
INLINE_CODE_34	Run only tests that failed in last run (last failed)
INLINE_CODE_35	Run failed tests first, then others (failed first)
INLINE_CODE_36	Show local variables in tracebacks on failure

/ Fortgeschrittene Nutzung

Command	Description
INLINE_CODE_37	Run tests in parallel using all available CPU cores (requires pytest-xdist)
INLINE_CODE_38	Run tests in parallel with 4 worker processes
INLINE_CODE_39	Show the 10 slowest test durations
INLINE_CODE_40	Show slowest tests taking at least 1 second
INLINE_CODE_41	Run tests with code coverage report (requires pytest-cov)
INLINE_CODE_42	Generate HTML coverage report in htmlcov/ directory
INLINE_CODE_43	Show coverage with missing line numbers in terminal
INLINE_CODE_44	Fail if coverage is below 80%
INLINE_CODE_45	Include branch coverage analysis
INLINE_CODE_46	Generate JUnit XML report for CI/CD integration
INLINE_CODE_47	Generate HTML test report (requires pytest-html)
INLINE_CODE_48	Drop into Python debugger (PDB) on test failures
INLINE_CODE_49	Drop into PDB at the start of each test
INLINE_CODE_50	Show setup and teardown of fixtures during execution
INLINE_CODE_51	List all available fixtures and their docstrings
INLINE_CODE_52	List all registered markers
INLINE_CODE_53	Use shorter traceback format
INLINE_CODE_54	Show one line per failure in traceback
INLINE_CODE_55	Disable traceback output
INLINE_CODE_56	Treat deprecation warnings as errors
INLINE_CODE_57	Disable output capturing (same as -s)
INLINE_CODE_58	Set timeout of 300 seconds per test (requires pytest-timeout)
INLINE_CODE_59	Repeat each test 3 times (requires pytest-repeat)
INLINE_CODE_60	Run tests in random order (requires pytest-random-order)
INLINE_CODE_61	Show short test summary for all tests (passed, failed, skipped, etc.)

Konfiguration

pytest.ini Datei konfigurieren¶

Ort im Projekt root-Verzeichnis:

[pytest]
# Minimum pytest version required
minversion = 7.0

# Directories to search for tests
testpaths = tests

# Test file patterns
python_files = test_*.py *_test.py

# Test class patterns
python_classes = Test* *Tests

# Test function patterns
python_functions = test_*

# Default command line options
addopts = 
    -ra
    --strict-markers
    --strict-config
    --verbose
    --cov=myproject
    --cov-report=html
    --cov-report=term-missing

# Custom markers
markers =
    slow: marks tests as slow (deselect with '-m "not slow"')
    integration: marks tests as integration tests
    unit: marks tests as unit tests
    smoke: marks tests as smoke tests
    database: marks tests requiring database connection
    api: marks tests for API testing

# Directories to ignore
norecursedirs = .git .tox dist build *.egg venv node_modules

# Warning filters
filterwarnings =
    error
    ignore::UserWarning
    ignore::DeprecationWarning

# Logging configuration
log_cli = true
log_cli_level = INFO
log_cli_format = %(asctime)s [%(levelname)s] %(message)s
log_cli_date_format = %Y-%m-%d %H:%M:%S

pyproject.toml Konfiguration¶

Moderne Python-Projekte mit pyproject.toml:

[tool.pytest.ini_options]
minversion = "7.0"
testpaths = ["tests"]
python_files = ["test_*.py", "*_test.py"]
python_classes = ["Test*"]
python_functions = ["test_*"]

addopts = [
    "-ra",
    "--strict-markers",
    "--cov=myproject",
    "--cov-branch",
    "--cov-report=html",
    "--cov-report=term-missing:skip-covered",
    "--cov-fail-under=80",
]

markers = [
    "slow: marks tests as slow",
    "integration: integration tests",
    "unit: unit tests",
    "smoke: smoke tests",
]

filterwarnings = [
    "error",
    "ignore::UserWarning",
]

conftest. py - Geteilte Reparaturen¶

Ort in Testverzeichnis Wurzel für freigegebene Geräte:

import pytest

# Session-scoped fixture (runs once per test session)
@pytest.fixture(scope="session")
def database():
    """Provide database connection for entire test session"""
    db = create_database_connection()
    yield db
    db.close()

# Module-scoped fixture (runs once per test module)
@pytest.fixture(scope="module")
def api_client():
    """Provide API client for test module"""
    client = APIClient()
    yield client
    client.cleanup()

# Function-scoped fixture (default, runs for each test)
@pytest.fixture
def sample_data():
    """Provide sample data for testing"""
    return {"id": 1, "name": "Test User"}

# Autouse fixture (automatically used by all tests)
@pytest.fixture(autouse=True)
def reset_state():
    """Reset application state before each test"""
    clear_cache()
    yield
    cleanup_resources()

# Parametrized fixture
@pytest.fixture(params=["sqlite", "postgres", "mysql"])
def db_type(request):
    """Test with multiple database types"""
    return request.param

# Configure pytest hooks
def pytest_configure(config):
    """Add custom configuration"""
    config.addinivalue_line(
        "markers", "custom: custom marker description"
    )

Häufige Anwendungsfälle

Use Case 1: Basic Unit Testing¶

# Create test file
cat > test_calculator.py << 'EOF'
def add(a, b):
    return a + b

def test_add():
    assert add(2, 3) == 5
    assert add(-1, 1) == 0
    assert add(0, 0) == 0
EOF

# Run the tests
pytest test_calculator.py -v

Use Case 2: Testen mit Fixtures¶

# Create test with fixtures
cat > test_user.py << 'EOF'
import pytest

@pytest.fixture
def user_data():
    return {"username": "testuser", "email": "test@example.com"}

def test_user_creation(user_data):
    assert user_data["username"] == "testuser"
    assert "@" in user_data["email"]
EOF

# Run tests with fixture details
pytest test_user.py -v --setup-show

Use Case 3: Parametrized Testing¶

# Create parametrized tests
cat > test_math.py << 'EOF'
import pytest

@pytest.mark.parametrize("input,expected", [
    (2, 4),
    (3, 9),
    (4, 16),
    (5, 25),
])
def test_square(input, expected):
    assert input ** 2 == expected
EOF

# Run parametrized tests
pytest test_math.py -v

Use Case 4: Integrationstest mit Markern¶

# Create tests with markers
cat > test_api.py << 'EOF'
import pytest

@pytest.mark.unit
def test_data_validation():
    assert True

@pytest.mark.integration
def test_api_endpoint():
    # Simulated API test
    assert True

@pytest.mark.slow
@pytest.mark.integration
def test_full_workflow():
    # Long-running test
    assert True
EOF

# Run only unit tests
pytest test_api.py -m unit -v

# Run integration tests excluding slow ones
pytest test_api.py -m "integration and not slow" -v

Use Case 5: Coverage Report Generation¶

# Run tests with coverage and generate reports
pytest --cov=myproject --cov-report=html --cov-report=term-missing

# View coverage report
# HTML report will be in htmlcov/index.html

# Run with coverage threshold
pytest --cov=myproject --cov-fail-under=80

# Generate coverage badge
pytest --cov=myproject --cov-report=term --cov-report=html

oder Best Practices

**Benutze beschreibende Testnamen*: Namenstests mit test_ Präfix und beschreiben, was sie testen (z.B. test_user_registration_with_valid_email)
**Folge AAA Muster*: Strukturtests mit Arrange (Setup), Act (execute), Assert (verify) Abschnitte für Klarheit
Benutze Geräte für Setup/Teardown: Leverage Pytests statt Setup/Teardown Methoden für bessere Wiederverwendbarkeit und Abhängigkeitsinjektion
Mark-Tests entsprechend: Verwenden Sie Marker (@pytest.mark.slow, @pytest.mark.integration_), um Tests zu kategorisieren und eine selektive Ausführung zu ermöglichen
**Keep-Tests isoliert* Jeder Test sollte unabhängig sein und sich nicht auf den Zustand von anderen Tests verlassen; Geräte mit entsprechenden Bereichen verwenden
**Benutze Parametrize für ähnliche Tests*: Anstatt mehrere ähnliche Tests zu schreiben, verwenden Sie @pytest.mark.parametrize, um mehrere Eingänge zu testen
Configure pytest.ini oder pyproject. toml: Legen Sie projektweite Standardeinstellungen für Testentdeckung, Marker und Befehlszeilenoptionen in Konfigurationsdateien fest
**Writ fokussierte Behauptungen*: Verwenden Sie einfache, klare Behauptungen; pytests Introspektion zeigt detaillierte Fehlerinformationen automatisch
**Benutze conftest.py für geteilte Geräte*: Platzieren Sie wiederverwendbare Geräte in conftest.py Dateien auf entsprechenden Verzeichnisebenen
**Lauftests häufig* Testen Sie während der Entwicklung mit pytest -x, um den ersten Ausfall für schnelleres Feedback zu stoppen
Monitor Testabdeckung: Regelmäßige Überprüfung der Berichterstattungsberichte und Ziel 80%+ Berichterstattung, aber Fokus auf sinnvolle Tests über Prozent

Fehlerbehebung

Issue	Solution
Tests not discovered	Ensure files match patterns: INLINE_CODE_69 or INLINE_CODE_70, functions start with INLINE_CODE_71, classes start with INLINE_CODE_72
Import errors in tests	Add empty INLINE_CODE_73 files in test directories, or install package in editable mode: INLINE_CODE_74
Fixture not found	Check fixture is defined in same file or INLINE_CODE_75, verify correct scope, ensure fixture name matches parameter
Tests pass locally but fail in CI	Check for environment-specific dependencies, ensure consistent Python versions, verify all dependencies in INLINE_CODE_76
Slow test execution	Use INLINE_CODE_77 to identify slow tests, consider parallel execution with INLINE_CODE_78, mark slow tests with INLINE_CODE_79
Coverage not working	Install pytest-cov: INLINE_CODE_80, ensure source path is correct: INLINE_CODE_81, check INLINE_CODE_82 configuration
Markers not recognized	Register markers in INLINE_CODE_83 or INLINE_CODE_84 under INLINE_CODE_85, use INLINE_CODE_86 to catch typos
PDB not working with capture	Use INLINE_CODE_87 to disable output capturing, or use INLINE_CODE_88 instead of INLINE_CODE_89
Fixtures running in wrong order	Check fixture scope (session > module > class > function), use INLINE_CODE_90 carefully, review dependency chain
Parallel tests failing	Ensure tests are isolated and don't share state, check for race conditions, use proper locking for shared resources
Memory leaks in tests	Use INLINE_CODE_91 for proper cleanup, ensure fixtures yield and cleanup properly, check for circular references
Warnings cluttering output	Konfigurieren Sie Warnfilter in `pytest.ini`: __INLINE_CODE_93_, oder verwenden Sie `-W`