Parametrize

Pytest · Reference cheat sheet

📋 Overview

@pytest.mark.parametrize runs one test body with many inputs. Combine with fixture params and pytest.param for ids, marks, and expected exceptions.

🔧 Core concepts

Form	Use
`@pytest.mark.parametrize`	Table-driven tests
`ids=`	Readable node ids
`pytest.param(..., marks=)`	Per-row marks
Indirect parametrization	Feed fixtures
Stacked parametrize	Cartesian product

💡 Examples

Simple table:

import pytest

@pytest.mark.parametrize(
    "a,b,expected",
    [
        (1, 1, 2),
        (2, 3, 5),
        (-1, 1, 0),
    ],
)
def test_add(a, b, expected):
    assert a + b == expected

Ids & marks:

@pytest.mark.parametrize(
    "value",
    [
        pytest.param(1, id="one"),
        pytest.param(0, marks=pytest.mark.xfail(reason="zero")),
        pytest.param(-1, marks=pytest.mark.skip(reason="neg")),
    ],
)
def test_value(value):
    assert value > 0

Indirect:

@pytest.fixture
def user(request):
    return User(role=request.param)

@pytest.mark.parametrize("user", ["admin", "guest"], indirect=True)
def test_access(user):
    assert user.role in {"admin", "guest"}

Cartesian:

@pytest.mark.parametrize("x", [1, 2])
@pytest.mark.parametrize("y", ["a", "b"])
def test_grid(x, y):
    assert f"{x}{y}"

⚠️ Pitfalls

Huge cartesian products exploding CI time.
Unhashable / huge objects as params — use factories/ids.
Duplicate ids causing confusion in reports.
Putting setup logic in params instead of fixtures.
Over-parametrizing when a property-based test fits better.

Parametrize

Parametrize

📋 Overview

🔧 Core concepts

💡 Examples

⚠️ Pitfalls

🔗 Related

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