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## General
`register_format()` allows you to add support for your custom file formats, such as the following `Array` type.
<!-- inline-snapshot-lib: my_array.py -->
``` python title="my_array.py"
from dataclasses import dataclass
from typing import List
@dataclass
class Array:
numbers: List[int]
```
[](){#array-example}
<!-- inline-snapshot-lib: conftest.py -->
``` python title="conftest.py"
from pathlib import Path
from inline_snapshot import register_format, TextDiff, Format
from my_array import Array
@register_format
class ArrayFormat(TextDiff, Format[Array]):
suffix = ".arr"
@staticmethod
def is_format_for(data: object):
return isinstance(data, Array)
@staticmethod
def encode(value: Array, path: Path):
with path.open("w", encoding="utf-8", newline="\n") as f:
f.write("\n".join(map(str, value.numbers)))
@staticmethod
def decode(path: Path) -> Array:
with path.open("r", encoding="utf-8", newline="\n") as f:
return Array(list(map(int, f.read().splitlines())))
```
You can then use `external()` to save this type into an external file.
<!-- inline-snapshot: first_block outcome-failed=1 outcome-errors=1 -->
``` python
from my_array import Array
from inline_snapshot import external
def test_array():
assert Array([1, 2, 3]) == external()
```
inline-snapshot will check if the type matches by using `is_format_for()` and create a file with the given suffix.
<!-- inline-snapshot: create outcome-passed=1 outcome-errors=1 -->
``` python hl_lines="6 7 8"
from my_array import Array
from inline_snapshot import external
def test_array():
assert Array([1, 2, 3]) == external(
"uuid:e3e70682-c209-4cac-a29f-6fbed82c07cd.arr"
)
```
### Report
inline-snapshot needs to know how changes in your external files should be displayed. `TextDiff` and `BinaryDiff` can be used as mixin classes (see the `Array` example (above)[#array-example]) to provide generic representations for text or binary formats, but you can also define custom functions for your files.
* `rich_diff()` is used every time the external snapshot value is changed and should show the difference between the original and new versions in a human-readable form.
* `rich_show()` is used every time an external snapshot is created and should show a human-readable form of the initial value.
<!-- inline-snapshot-lib-set: conftest.py -->
``` python title="conftest.py"
from pathlib import Path
from inline_snapshot import register_format, Format, external
from number_set import NumberSet
@register_format
class NumberSetFormat(Format[NumberSet]):
suffix = ".numberset"
def rich_diff(self, original: Path, new: Path):
original_numbers = set(self.decode(original).numbers)
new_numbers = set(self.decode(new).numbers)
return (
f"new numbers: [green]{new_numbers-original_numbers}[/]\n"
f"removed numbers: [red]{original_numbers-new_numbers}[/]"
)
def rich_show(self, path: Path):
return " ".join(f"[blue]{n}[/]" for n in self.decode(path).numbers)
def is_format_for(self, data: object):
return isinstance(data, NumberSet)
def encode(self, value: NumberSet, path: Path):
with path.open("w", encoding="utf-8", newline="\n") as f:
f.write("\n".join(sorted(map(str, value.numbers))))
def decode(self, path: Path) -> NumberSet:
with path.open("r", encoding="utf-8", newline="\n") as f:
return NumberSet(set(map(int, f.read().splitlines())))
```
<!-- inline-snapshot-lib: number_set.py -->
``` python title="number_set.py"
from dataclasses import dataclass
from typing import Set
@dataclass
class NumberSet:
numbers: Set[int]
```
The custom format is then used every time a `NumberSet` is compared with an empty external.
=== "example pytest output"
=== "example"
<!-- inline-snapshot: create first_block outcome-failed=1 -->
``` python
from inline_snapshot import external
from number_set import NumberSet
def test():
assert NumberSet([1, 2, 5]) == external("hash:b85198032326*.numberset")
assert NumberSet([1, 2, 8]) == external("hash:f8a68eb0c510*.numberset")
```
## Reference
::: inline_snapshot
options:
heading_level: 3
members: [register_format, register_format_alias, Format]
show_root_heading: false
show_bases: false
show_source: false
|
