inline-snapshot · Python Simple Repository Browser

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Author: Frank Hoffmann

Requires Python: >=3.9

Classifiers

Development Status

4 - Beta

Framework

Pytest

Intended Audience

Developers

License

OSI Approved :: MIT License

Operating System

OS Independent

Programming Language

Python
Python :: 3.9
Python :: 3.10
Python :: 3.11
Python :: 3.12
Python :: 3.13
Python :: 3.14
Python :: Implementation :: CPython
Python :: Implementation :: PyPy

Topic

Software Development :: Testing

Python Versions

Installation

You can install "inline-snapshot" via pip:

pip install inline-snapshot

Key Features

support for normal assertions: inline-snapshot can now also fix normal assertions which do not use snapshot() like:
```
assert 1 + 1 == 3
```
You can learn here more about this feature.
Intuitive Semantics: snapshot(x) mirrors x for easy understanding.
Versatile Comparison Support: Equipped with x == snapshot(...), x <= snapshot(...), x in snapshot(...), and snapshot(...)[key].
No CLI arguments required: you will get a nice report where you can review the snapshot changes when you run pytest (only for CPython > 3.11, you have to use --inline-snapshot=review on older versions).
Enhanced Control Flags: Utilize various flags for precise control of which snapshots you want to change.
Preserved Formatting: Retains formatting consistency with Black formatting or a custom format-command.
External File Storage: Store snapshots externally using external("uuid:eb1167b3-67a9-4378-bc65-c1e582e2e662.json") with support for custom file formats.
Seamless Pytest Integration: Integrated seamlessly with pytest for effortless testing.
Integration into normal functions: use snapshot_arg() to convert the arguments of your function into snapshots.
Customizable: code generation can be customized with @customize
Nested Snapshot Support: snapshots can contain other snapshots
Fuzzy Matching: Incorporate dirty-equals for flexible comparisons within snapshots.
Dynamic Snapshot Content: snapshots 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 external, outsource, snapshot


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("hash:8bf10bdf2c30*.txt")
    )

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

snapshot_arg() can also be used for function parameters:

import subprocess as sp
import sys
from inline_snapshot import snapshot_arg


def run_python(cmd, stdout="", stderr=""):
    result = sp.run([sys.executable, "-c", cmd], capture_output=True)
    assert result.stdout.decode() == snapshot_arg(stdout)
    assert result.stderr.decode() == snapshot_arg(stderr)


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

    run_python(
        "1/0",
        stderr="""\
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.