Add required space when fixing SIM118 (#7150)

crates/ruff/resources/test/fixtures/flake8_simplify/SIM118.py

@@ -42,3 +42,9 @@ class Foo:
 
     def __contains__(self, key: object) -> bool:
         return key in self.keys()  # OK
+
+
+# Regression test for: https://github.com/astral-sh/ruff/issues/7124
+key in obj.keys()and foo
+(key in obj.keys())and foo
+key in (obj.keys())and foo

crates/ruff/src/rules/flake8_simplify/rules/key_in_dict.rs

@@ -116,8 +116,24 @@ fn key_in_dict(
         TextRange::new(left_range.start(), right_range.end()),
     );
     if checker.patch(diagnostic.kind.rule()) {
+        // If the `.keys()` is followed by (e.g.) a keyword, we need to insert a space,
+        // since we're removing parentheses, which could lead to invalid syntax, as in:
+        // ```python
+        // if key in foo.keys()and bar:
+        // ```
+        let requires_space = checker
+            .locator()
+            .after(right_range.end())
+            .chars()
+            .next()
+            .is_some_and(|char| char.is_ascii_alphabetic());
+
         diagnostic.set_fix(Fix::suggested(Edit::range_replacement(
-            value_content.to_string(),
+            if requires_space {
+                format!("{value_content} ")
+            } else {
+                value_content.to_string()
+            },
             right_range,
         )));
     }

crates/ruff/src/rules/flake8_simplify/snapshots/ruff__rules__flake8_simplify__tests__SIM118_SIM118.py.snap

@@ -309,4 +309,57 @@ SIM118.py:34:1: SIM118 [*] Use `(key) in (obj or {})` instead of `(key) in (obj
 36 36 | from typing import KeysView
 37 37 | 
 
+SIM118.py:48:1: SIM118 [*] Use `key in obj` instead of `key in obj.keys()`
+   |
+47 | # Regression test for: https://github.com/astral-sh/ruff/issues/7124
+48 | key in obj.keys()and foo
+   | ^^^^^^^^^^^^^^^^^ SIM118
+49 | (key in obj.keys())and foo
+50 | key in (obj.keys())and foo
+   |
+   = help: Convert to `key in obj`
+
+ℹ Suggested fix
+45 45 | 
+46 46 | 
+47 47 | # Regression test for: https://github.com/astral-sh/ruff/issues/7124
+48    |-key in obj.keys()and foo
+   48 |+key in obj and foo
+49 49 | (key in obj.keys())and foo
+50 50 | key in (obj.keys())and foo
+
+SIM118.py:49:2: SIM118 [*] Use `key in obj` instead of `key in obj.keys()`
+   |
+47 | # Regression test for: https://github.com/astral-sh/ruff/issues/7124
+48 | key in obj.keys()and foo
+49 | (key in obj.keys())and foo
+   |  ^^^^^^^^^^^^^^^^^ SIM118
+50 | key in (obj.keys())and foo
+   |
+   = help: Convert to `key in obj`
+
+ℹ Suggested fix
+46 46 | 
+47 47 | # Regression test for: https://github.com/astral-sh/ruff/issues/7124
+48 48 | key in obj.keys()and foo
+49    |-(key in obj.keys())and foo
+   49 |+(key in obj)and foo
+50 50 | key in (obj.keys())and foo
+
+SIM118.py:50:1: SIM118 [*] Use `key in obj` instead of `key in obj.keys()`
+   |
+48 | key in obj.keys()and foo
+49 | (key in obj.keys())and foo
+50 | key in (obj.keys())and foo
+   | ^^^^^^^^^^^^^^^^^^^ SIM118
+   |
+   = help: Convert to `key in obj`
+
+ℹ Suggested fix
+47 47 | # Regression test for: https://github.com/astral-sh/ruff/issues/7124
+48 48 | key in obj.keys()and foo
+49 49 | (key in obj.keys())and foo
+50    |-key in (obj.keys())and foo
+   50 |+key in obj and foo
+