snappiershot 1.0.0

Snapshot testing library.

SnappierShot

Add snapshot testing to your testing toolkit.

Installation

$ pip install snappiershot

Configuration

SnappierShot is following the trend of packages in performing project-wide configuration through the pyproject.toml file established by PEP 518.

Within the pyproject.toml file, all SnappierShot configuration can be found under the [tool.snappiershot] heading.

Example (with default values):

[tool.snappiershot]
file_format = "json"
float_absolute_tolerance = 1e-6
float_relative_tolerance = 0.001
full_diff = false
json_indentation = 4

Usage

SnappierShot allows you to take a "snapshot" of data the first time that a test is run, and stores it nearby in a .snapshots directory. Then, for all subsequent times that test is run, the data is assert to "match" the original data.

Pytest Example

def test_something(snapshot):
    """ Test that something works as expected"""
    # Arrange
    x = 1
    y = 2

    # Act
    result = x + y

    # Assert
    snapshot.assert_match(result)

No Test Runner Example

from snappiershot import Snapshot

def test_something():
    """ Test that something works as expected"""
    # Arrange
    x = 1
    y = 2

    # Act
    result = x + y

    # Assert
    with Snapshot() as snapshot
        snapshot.assert_match(result)

test_something()

Raises

Snappiershot also allows you to take a "snapshot" errors that are raised during the execution of a code block. This allows you to track how and when errors are reported more easily.

def fallible_function():
    """ A function with an error state. """
    raise RuntimeError("An error occurred!")


def test_fallible_function(snapshot):
    """ Test that errors are being reported as expected"""
    # Arrange

    # Act & Assert
    with snapshot.raises(RuntimeError):
        fallible_function()

Support Types:

• Primitives (bool, int, float, None, str)
• Numerics (complex)
• Collections (lists, tuples, sets)
• Dictionaries
• Classes (with an underlying __dict__)
• Classes with custom encoding (by defining a __snapshot__ method).

Contributing

See CONTRIBUTING.md