Add RUF010

.pre-commit-config.yaml

@@ -11,7 +11,7 @@ repos:
       - id: end-of-file-fixer
       - id: trailing-whitespace
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.2.1
+    rev: v0.2.2
     hooks:
       - id: ruff-format
       - id: ruff

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## 0.3.0 (2024-02-18)
+
+- Add `RUF010` check.
+
 ## 0.2.0 (2024-02-17)
 
 - Add `RUF018` check.

README.md

@@ -24,6 +24,31 @@ to enable the plugin.
 
 ## Checks
 
+### RUF010 Use explicit conversion flag
+
+Checks for `str()`, `repr()`, and `ascii()` as explicit conversions within
+f-strings.
+
+For example, replace
+
+```python
+f"{ascii(foo)}, {repr(bar)}, {str(baz)}"
+```
+
+with
+
+```python
+f"{foo!a}, {bar!r}, {baz!s}"
+```
+
+or, often (such as where `__str__` and `__format__` are equivalent),
+
+```python
+f"{foo!a}, {bar!r}, {baz}"
+```
+
+Derived from [explicit-f-string-type-conversion (RUF010)](https://docs.astral.sh/ruff/rules/explicit-f-string-type-conversion/).
+
 ### RUF018 Avoid assignment expressions in `assert` statements
 
 Checks for named assignment expressions in `assert` statements. When Python is

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "flake8-ruff"
-version = "0.2.0"
+version = "0.3.0"
 description = "A Flake8 plugin that implements miscellaneous checks from Ruff."
 license = "MIT"
 authors = ["Tom Kuson <[email protected]>"]

src/flake8_ruff/__init__.py

@@ -3,6 +3,7 @@
 import ast
 import typing
 
+RUF010 = "RUF010 Use explicit conversion flag"
 RUF018 = "RUF018 Avoid assignment expressions in assert statements"
 RUF020 = "RUF020 {} | T is equivalent to T"
 RUF025 = "RUF025 Unnecessary dict comprehension for iterable; use dict.fromkeys instead"
@@ -37,6 +38,24 @@ def visit(self, node: ast.AST) -> None:
         super().visit(node)
         self._stack.pop()
 
+    def visit_FormattedValue(self, node: ast.FormattedValue) -> None:
+        if (
+            node.conversion == -1
+            and isinstance(node.value, ast.Call)
+            and not node.value.keywords
+            and len(node.value.args) == 1
+            and not isinstance(
+                node.value.args[0], (ast.Dict, ast.DictComp, ast.Set, ast.SetComp)
+            )
+            and isinstance(node.value.func, ast.Name)
+            and node.value.func.id in {"ascii", "repr", "str"}
+        ):
+            self.errors.append((
+                node.lineno,
+                node.col_offset,
+                RUF010,
+            ))
+
     def visit_DictComp(self, node: ast.DictComp) -> None:
         if (
             len(node.generators) == 1
@@ -79,6 +98,7 @@ def visit_Subscript(self, node: ast.Subscript) -> None:
 
     def visit_Assert(self, node: ast.Assert) -> None:
         if isinstance(node.test, ast.NamedExpr):
+            # TODO(tom): Determine why col_offset is different on Python 3.12
             self.errors.append((
                 node.lineno,
                 node.col_offset,

tests/test_flake8_ruff.py

@@ -11,6 +11,46 @@ def run(source: str) -> list[tuple[int, int, str]]:
     return [(line, col, msg) for (line, col, msg, type_) in Plugin(tree).run()]
 
 
+def test_ruf010_ascii() -> None:
+    src = """\
+    f"abc {ascii(bar)} xyz"
+    """
+    expected_msg = "RUF010 Use explicit conversion flag"
+    assert expected_msg == run(src)[0][2]
+
+
+def test_ruf010_repr() -> None:
+    src = """\
+    f"abc {repr(123)} xyz"
+    """
+    expected_msg = "RUF010 Use explicit conversion flag"
+    assert expected_msg == run(src)[0][2]
+
+
+def test_ruf010_str() -> None:
+    src = """\
+    f"abc {(str(123))} xyz"
+    """
+    expected_msg = "RUF010 Use explicit conversion flag"
+    assert expected_msg == run(src)[0][2]
+
+
+def test_ruf010_set() -> None:
+    src = """\
+    f"abc {str({})} xyz"
+    """
+    expected: list[tuple[int, int, str]] = []
+    assert expected == run(src)
+
+
+def test_ruf010_dict() -> None:
+    src = """\
+    f"abc {str({k: v for k, v in enumerate(foo)})} xyz"
+    """
+    expected: list[tuple[int, int, str]] = []
+    assert expected == run(src)
+
+
 def test_ruf018() -> None:
     src = """\
     assert (x := 1), "message"