Categories

Each snapshot change is assigned to a different category. This is done because inline-snapshot supports more than just == checks.

There are changes which:

create new snapshot values
fix your tests
update only the syntax to a new representation
trim unused pieces from your snapshots

Create and fix are mainly used, but it is good to know what type of change you are approving, because it helps with the decision if this changes should be applied.

Categories¶

Create¶

These changes are made when new snapshots are created.

The result of each comparison is True, which allows to run the whole test to fill all new snapshots with values.

Example:

def test_something():
    assert 5 == snapshot()

    assert 5 <= snapshot()

    assert 5 in snapshot()

    s = snapshot()
    assert 5 == s["key"]

def test_something():
    assert 5 == snapshot(5)

    assert 5 <= snapshot(5)

    assert 5 in snapshot([5])

    s = snapshot({"key": 5})
    assert 5 == s["key"]

Fix¶

These changes are made when the snapshots comparison does not return True any more (depending on the operation ==, <=, in). The result of each comparison is True if you change something from this category, which allows to run the whole test and to fix other snapshots.

def test_something():
    assert 8 == snapshot(5)

    assert 8 <= snapshot(5)

    assert 8 in snapshot([5])

    s = snapshot({"key": 5})
    assert 8 == s["key"]

def test_something():
    assert 8 == snapshot(8)

    assert 8 <= snapshot(8)

    assert 8 in snapshot([5, 8])

    s = snapshot({"key": 8})
    assert 8 == s["key"]

Info

The main reason for the different categories is to make the number of changes in the fix category as small as possible. The changes in the fix category are the only changes which change the value of the snapshots and should be reviewed carefully.

Trim¶

These changes are made when parts of the snapshots are removed which are no longer needed, or if limits can be reduced.

def test_something():
    assert 2 <= snapshot(8)

    assert 8 in snapshot([5, 8])

    s = snapshot({"key1": 1, "key2": 2})
    assert 2 == s["key2"]

def test_something():
    assert 2 <= snapshot(2)

    assert 8 in snapshot([8])

    s = snapshot({"key2": 2})
    assert 2 == s["key2"]

There might be problems in cases where you use the same snapshot in different tests, run only one test and trim the snapshot with pytest -k test_a --inline-snapshot=trim in this case:

s = snapshot(5)


def test_a():
    assert 2 <= s


def test_b():
    assert 5 <= s

s = snapshot(2)


def test_a():
    assert 2 <= s


def test_b():
    assert 5 <= s

The value of the snapshot is reduced to 2, because test_a() was the only test running and inline-snapshot does not know about 5 <= s. It is recommended to use trim only if you run your complete test suite.

Update¶

Changes in the update category do not change the value in the code, just the representation. The reason might be that repr() of the object has changed or that inline-snapshot provides some new logic which changes the representation. Like with the strings in the following example:

original--inline-snapshot=update

class Vector:
    def __init__(self, x, y):
        self.x = x
        self.y = y

    def __eq__(self, other):
        if not isinstance(other, Vector):
            return NotImplemented
        return self.x == other.x and self.y == other.y

    def __repr__(self):
        # return f"Vector(x={self.x}, y={self.y})"
        return f"Vector({self.x}, {self.y})"


def test_something():
    assert "a\nb\nc\n" == snapshot("a\nb\nc\n")

    assert 5 == snapshot(4 + 1)

    assert Vector(1, 2) == snapshot(Vector(x=1, y=2))

class Vector:
    def __init__(self, x, y):
        self.x = x
        self.y = y

    def __eq__(self, other):
        if not isinstance(other, Vector):
            return NotImplemented
        return self.x == other.x and self.y == other.y

    def __repr__(self):
        # return f"Vector(x={self.x}, y={self.y})"
        return f"Vector({self.x}, {self.y})"


def test_something():
    assert "a\nb\nc\n" == snapshot(
        """\
a
b
c
"""
    )

    assert 5 == snapshot(5)

    assert Vector(1, 2) == snapshot(Vector(1, 2))

The approval of this type of changes is easier, because inline-snapshot assures that the value has not changed.