Simplify decorators that are too hard to parse (#284)

Author: jendrikseipp

CHANGELOG.md

@@ -1,5 +1,6 @@
 # 2.9 (unreleased)
 * Use exit code 3 when dead code is found (whosayn, #319).
+* Simplify decorator names that are too hard to parse to "@" (Llandy3d and Jendrik Seipp, #284).
 
 # 2.8 (2023-08-10)
 

README.md

@@ -111,7 +111,9 @@ starting with `foo` and the names `bar` and `baz`. Additionally, the
 `--ignore-decorators` option can be used to ignore functions decorated
 with the given decorator. This is helpful for example in Flask projects,
 where you can use `--ignore-decorators "@app.route"` to ignore all
-functions with the `@app.route` decorator.
+functions with the `@app.route` decorator. Note that Vulture simplifies
+decorators it cannot parse: `@foo.bar(x, y)` becomes "@foo.bar" and
+`@foo.bar(x, y).baz` becomes "@" internally.
 
 We recommend using whitelists instead of `--ignore-names` or
 `--ignore-decorators` whenever possible, since whitelists are

tests/test_utils.py

@@ -1,6 +1,7 @@
 import ast
 import os
 import pathlib
+import sys
 
 import pytest
 
@@ -119,3 +120,40 @@ class Foo:
     pass
 """
     check_decorator_names(code, ["@foo", "@bar.yz"])
+
+
+def test_get_decorator_name_end_function_call():
+    code = """\
+@foo.bar(x, y, z)
+def bar():
+    pass
+"""
+    check_decorator_names(code, ["@foo.bar"])
+
+
+@pytest.mark.skipif(
+    sys.version_info < (3, 9), reason="requires Python 3.9 or higher"
+)
+@pytest.mark.parametrize(
+    "decorated",
+    [
+        ("def foo():"),
+        ("async def foo():"),
+        ("class Foo:"),
+    ],
+)
+def test_get_decorator_name_multiple_callables(decorated):
+    decorated = f"{decorated}\n    pass"
+    code = f"""\
+@foo
+@bar.prop
+@z.func("hi").bar().k.foo
+@k("hello").doo("world").x
+@k.hello("world")
+@foo[2]
+{decorated}
+"""
+    check_decorator_names(
+        code,
+        ["@foo", "@bar.prop", "@", "@", "@k.hello", "@"],
+    )

vulture/utils.py

@@ -64,11 +64,14 @@ def format_path(path):
 def get_decorator_name(decorator):
     if isinstance(decorator, ast.Call):
         decorator = decorator.func
-    parts = []
-    while isinstance(decorator, ast.Attribute):
-        parts.append(decorator.attr)
-        decorator = decorator.value
-    parts.append(decorator.id)
+    try:
+        parts = []
+        while isinstance(decorator, ast.Attribute):
+            parts.append(decorator.attr)
+            decorator = decorator.value
+        parts.append(decorator.id)
+    except AttributeError:
+        parts = []
     return "@" + ".".join(reversed(parts))