Installation

You can install "inline-snapshot" via pip:

pip install inline-snapshot

Key Features

• Intuitive Semantics: snapshot(x) mirrors x for easy understanding.
• Versatile Comparison Support: Equipped with x == snapshot(...), x <= snapshot(...), x in snapshot(...), and snapshot(...)[key].
• Enhanced Control Flags: Utilize various flags for precise control of which snapshots you want to change.
• Preserved Black Formatting: Retains formatting consistency with Black formatting.
• External File Storage: Store snapshots externally using outsource(data).
• Seamless Pytest Integration: Integrated seamlessly with pytest for effortless testing.
• Customizable: code generation can be customized with @customize_repr
• Nested Snapshot Support: snapshots can contain other snapshots
• Fuzzy Matching: Incorporate dirty-equals for flexible comparisons within snapshots.
• Dynamic Snapshot Content: snashots can contain non-constant values
• Comprehensive Documentation: Access detailed documentation for complete guidance.

Usage

You can use snapshot() instead of the value which you want to compare with.

from inline_snapshot import snapshot


def test_something():
    assert 1548 * 18489 == snapshot()

You can now run the tests and record the correct values.

$ pytest --inline-snapshot=review

from inline_snapshot import snapshot


def test_something():
    assert 1548 * 18489 == snapshot(28620972)

The following examples show how you can use inline-snapshot in your tests. Take a look at the documentation if you want to know more.

from inline_snapshot import snapshot, outsource, external


def test_something():
    for number in range(5):
        # testing for numeric limits
        assert number <= snapshot(4)
        assert number >= snapshot(0)

    for c in "hello world":
        # test if something is part of a set
        assert c in snapshot(["h", "e", "l", "o", " ", "w", "r", "d"])

    s = snapshot(
        {
            0: {"square": 0, "pow_of_two": False},
            1: {"square": 1, "pow_of_two": True},
            2: {"square": 4, "pow_of_two": True},
            3: {"square": 9, "pow_of_two": False},
            4: {"square": 16, "pow_of_two": True},
        }
    )

    for number in range(5):
        # create sub-snapshots at runtime
        assert s[number]["square"] == number**2
        assert s[number]["pow_of_two"] == (
            (number & (number - 1) == 0) and number != 0
        )

    assert outsource("large string\n" * 1000) == snapshot(
        external("8bf10bdf2c30*.txt")
    )

    assert "generates\nmultiline\nstrings" == snapshot(
        """\
generates
multiline
strings\
"""
    )

snapshot() can also be used as parameter for functions:

from inline_snapshot import snapshot
import subprocess as sp
import sys


def run_python(cmd, stdout=None, stderr=None):
    result = sp.run([sys.executable, "-c", cmd], capture_output=True)
    if stdout is not None:
        assert result.stdout.decode() == stdout
    if stderr is not None:
        assert result.stderr.decode() == stderr


def test_cmd():
    run_python(
        "print('hello world')",
        stdout=snapshot(
            """\
hello world
"""
        ),
        stderr=snapshot(""),
    )

    run_python(
        "1/0",
        stdout=snapshot(""),
        stderr=snapshot(
            """\
Traceback (most recent call last):
  File "<string>", line 1, in <module>
ZeroDivisionError: division by zero
"""
        ),
    )

Feedback

inline-snapshot provides some advanced ways to work with snapshots.

I would like to know how these features are used to further improve this small library. Let me know if you've found interesting use cases for this library via twitter, fosstodon or in the github discussions.

Sponsors

I would like to thank my sponsors. Without them, I would not be able to invest so much time in my projects.

Bronze sponsor 🥉

Issues

If you encounter any problems, please report an issue along with a detailed description.

License

Distributed under the terms of the MIT license, "inline-snapshot" is free and open source software.