Update `F841` autofix to not remove line magic expr (#6141)

## Summary

Update `F841` autofix to not remove line magic expr

## Test Plan

Added test case for assignment statement with and without type
annotation

fixes: #6116

crates/ruff/resources/test/fixtures/jupyter/unused_variable.ipynb

@@ -0,0 +1,49 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "a0efffbc-85f1-4513-bf49-5387ec3a2a4e",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "def f():\n",
+    "    foo1 = %matplotlib --list\n",
+    "    foo2: list[str] = %matplotlib --list"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "6e0b2b50-43f2-4f59-951d-9404dd560ae4",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "def f():\n",
+    "    bar1 = !pwd\n",
+    "    bar2: str = !pwd"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python (ruff)",
+   "language": "python",
+   "name": "ruff"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.11.3"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}

crates/ruff/resources/test/fixtures/jupyter/unused_variable_expected.ipynb

@@ -0,0 +1,49 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "24426ef2-046c-453e-b809-05b56e7355e0",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "def f():\n",
+    "    %matplotlib --list\n",
+    "    %matplotlib --list"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "3d98fdae-b86b-476e-b4db-9d3ce5562682",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "def f():\n",
+    "    !pwd\n",
+    "    !pwd"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python (ruff)",
+   "language": "python",
+   "name": "ruff"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.11.3"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}

crates/ruff/src/jupyter/notebook.rs

@@ -582,6 +582,18 @@ print("after empty cells")
         Ok(())
     }
 
+    #[test]
+    fn test_unused_variable() -> Result<()> {
+        let path = "unused_variable.ipynb".to_string();
+        let (diagnostics, source_kind, _) = test_notebook_path(
+            &path,
+            Path::new("unused_variable_expected.ipynb"),
+            &settings::Settings::for_rule(Rule::UnusedVariable),
+        )?;
+        assert_messages!(diagnostics, path, source_kind);
+        Ok(())
+    }
+
     #[test]
     fn test_json_consistency() -> Result<()> {
         let path = "before_fix.ipynb".to_string();

crates/ruff/src/jupyter/snapshots/ruff__jupyter__notebook__tests__unused_variable.snap

@@ -0,0 +1,72 @@
+---
+source: crates/ruff/src/jupyter/notebook.rs
+---
+unused_variable.ipynb:cell 1:2:5: F841 [*] Local variable `foo1` is assigned to but never used
+  |
+1 | def f():
+2 |     foo1 = %matplotlib --list
+  |     ^^^^ F841
+3 |     foo2: list[str] = %matplotlib --list
+  |
+  = help: Remove assignment to unused variable `foo1`
+
+ℹ Suggested fix
+1 1 | def f():
+2   |-    foo1 = %matplotlib --list
+  2 |+    %matplotlib --list
+3 3 |     foo2: list[str] = %matplotlib --list
+4 4 | def f():
+5 5 |     bar1 = !pwd
+
+unused_variable.ipynb:cell 1:3:5: F841 [*] Local variable `foo2` is assigned to but never used
+  |
+1 | def f():
+2 |     foo1 = %matplotlib --list
+3 |     foo2: list[str] = %matplotlib --list
+  |     ^^^^ F841
+  |
+  = help: Remove assignment to unused variable `foo2`
+
+ℹ Suggested fix
+1 1 | def f():
+2 2 |     foo1 = %matplotlib --list
+3   |-    foo2: list[str] = %matplotlib --list
+  3 |+    %matplotlib --list
+4 4 | def f():
+5 5 |     bar1 = !pwd
+6 6 |     bar2: str = !pwd
+
+unused_variable.ipynb:cell 2:2:5: F841 [*] Local variable `bar1` is assigned to but never used
+  |
+1 | def f():
+2 |     bar1 = !pwd
+  |     ^^^^ F841
+3 |     bar2: str = !pwd
+  |
+  = help: Remove assignment to unused variable `bar1`
+
+ℹ Suggested fix
+2 2 |     foo1 = %matplotlib --list
+3 3 |     foo2: list[str] = %matplotlib --list
+4 4 | def f():
+5   |-    bar1 = !pwd
+  5 |+    !pwd
+6 6 |     bar2: str = !pwd
+
+unused_variable.ipynb:cell 2:3:5: F841 [*] Local variable `bar2` is assigned to but never used
+  |
+1 | def f():
+2 |     bar1 = !pwd
+3 |     bar2: str = !pwd
+  |     ^^^^ F841
+  |
+  = help: Remove assignment to unused variable `bar2`
+
+ℹ Suggested fix
+3 3 |     foo2: list[str] = %matplotlib --list
+4 4 | def f():
+5 5 |     bar1 = !pwd
+6   |-    bar2: str = !pwd
+  6 |+    !pwd
+
+

crates/ruff_python_ast/src/helpers.rs

@@ -111,6 +111,7 @@ where
                 | Expr::Subscript(_)
                 | Expr::Yield(_)
                 | Expr::YieldFrom(_)
+                | Expr::LineMagic(_)
         )
     })
 }