Add --diff option ruff format

crates/ruff_cli/resources/test/fixtures/formatted.py

@@ -0,0 +1 @@
+print("All formatted!")

crates/ruff_cli/resources/test/fixtures/unformatted.ipynb

@@ -0,0 +1,37 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "98e1dd71-14a2-454d-9be0-061dde560b07",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import numpy\n",
+    "maths = (numpy.arange(100)**2).sum()\n",
+    "stats= numpy.asarray([1,2,3,4]).median()"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3 (ipykernel)",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.10.12"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}

crates/ruff_cli/resources/test/fixtures/unformatted.py

@@ -0,0 +1,3 @@
+x = 1
+y=2
+z = 3

crates/ruff_cli/src/args.rs

@@ -353,6 +353,10 @@ pub struct FormatCommand {
     /// files would have been modified, and zero otherwise.
     #[arg(long)]
     pub check: bool,
+    /// Avoid writing any formatted files back; instead, exit with a non-zero status code and the
+    /// difference between the current file and how the formatted file would look like.
+    #[arg(long)]
+    pub diff: bool,
     /// Path to the `pyproject.toml` or `ruff.toml` file to use for configuration.
     #[arg(long, conflicts_with = "isolated")]
     pub config: Option<PathBuf>,
@@ -520,6 +524,7 @@ impl FormatCommand {
         (
             FormatArguments {
                 check: self.check,
+                diff: self.diff,
                 config: self.config,
                 files: self.files,
                 isolated: self.isolated,
@@ -577,6 +582,7 @@ pub struct CheckArguments {
 #[allow(clippy::struct_excessive_bools)]
 pub struct FormatArguments {
     pub check: bool,
+    pub diff: bool,
     pub config: Option<PathBuf>,
     pub files: Vec<PathBuf>,
     pub isolated: bool,