**Summary** `ruff format --diff` is similar to `ruff format --check`,
but we don't only error with the list of file that would be formatted,
but also show a diff between the unformatted input and the formatted
output.
```console
$ ruff format --diff scratch.py scratch.pyi scratch.ipynb
warning: `ruff format` is not yet stable, and subject to change in future versions.
--- scratch.ipynb
+++ scratch.ipynb
@@ -1,3 +1,4 @@
import numpy
-maths = (numpy.arange(100)**2).sum()
-stats= numpy.asarray([1,2,3,4]).median()
+
+maths = (numpy.arange(100) ** 2).sum()
+stats = numpy.asarray([1, 2, 3, 4]).median()
--- scratch.py
+++ scratch.py
@@ -1,3 +1,3 @@
x = 1
-y=2
+y = 2
z = 3
2 files would be reformatted, 1 file left unchanged
```
With `--diff`, the summary message gets printed to stderr to allow e.g.
`ruff format --diff . > format.patch`.
At the moment, jupyter notebooks are formatted as code diffs, while
everything else is a real diff that could be applied. This means that
the diffs containing jupyter notebooks are not real diffs and can't be
applied. We could change this to json diffs, but they are hard to read.
We could also split the diff option into a human diff option, where we
deviate from the machine readable diff constraints, and a proper machine
readable, appliable diff output that you can pipe into other tools.
To make the tests work, the results (and errors, if any) are sorted
before printing them. Previously, the print order was random, i.e. two
identical runs could have different output.
Open question: Should this go into the markdown docs? Or will this be
subsumed by the integration of the formatter into `ruff check`?
**Test plan** Fixtures for the change and no change cases, including a
jupyter notebook and for file input and stdin.
Fixes#7231
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
See the provided breaking changes note for details.
Removes support for the deprecated `--format`option in the `ruff check`
CLI, `format` inference as `output-format` in the configuration file,
and the `RUFF_FORMAT` environment variable.
The error message for use of `format` in the configuration file could be
better, but would require some awkward serde wrappers and it seems hard
to present the correct schema to the user still.
## Summary
This PR adds a new `cell` field to the JSON output format which
indicates the Notebook cell this diagnostic (and fix) belongs to. It
also updates the location for the diagnostic and fixes as per the
`NotebookIndex`. It will be used in the VSCode extension to display the
diagnostic in the correct cell.
The diagnostic and edit start and end source locations are translated
for the notebook as per the `NotebookIndex`. The end source location for
an edit needs some special handling.
### Edit end location
To understand this, the following context is required:
1. Visible lines in Jupyter Notebook vs JSON array strings: The newline
is part of the string in the JSON format. This means that if there are 3
visible lines in a cell where the last line is empty then the JSON would
contain 2 strings in the source array, both ending with a newline:
**JSON format:**
```json
[
"# first line\n",
"# second line\n",
]
```
**Notebook view:**
```python
1 # first line
2 # second line
3
```
2. If an edit needs to remove an entire line including the newline, then
the end location would be the start of the next row.
To remove a statement in the following code:
```python
import os
```
The edit would be:
```
start: row 1, col 1
end: row 2, col 1
```
Now, here's where the problem lies. The notebook index doesn't have any
information for row 2 because it doesn't exists in the actual notebook.
The newline was added by Ruff to concatenate the source code and it's
removed before writing back. But, the edit is computed looking at that
newline.
This means that while translating the end location for an edit belong to
a Notebook, we need to check if both the start and end location belongs
to the same cell. If not, then the end location should be the first
character of the next row and if so, translate that back to the last
character of the previous row. Taking the above example, the translated
location for Notebook would be:
```
start: row 1, col 1
end: row 1, col 10
```
## Test Plan
Add test cases for notebook output in the JSON format and update
existing snapshots.
After working with the previous change in
https://github.com/astral-sh/ruff/pull/7821 I found the names a bit
unclear and their relationship with the user-facing API muddied. Since
the applicability is exposed to the user directly in our JSON output, I
think it's important that these names align with our configuration
options. I've replaced `Manual` or `Never` with `Display` which captures
our intent for these fixes (only for display). Here, we create room for
future levels, such as `HasPlaceholders`, which wouldn't fit into the
`Always`/`Sometimes`/`Never` levels.
Unlike https://github.com/astral-sh/ruff/pull/7819, this retains the
flat enum structure which is easier to work with.
