Fix decorator parsing for async functions

docs/release_notes.rst

@@ -25,6 +25,8 @@ New Features
 Bug Fixes
 
 * Fix ``--match`` option to only consider filename when matching full paths (#550).
+* Fix decorator parsing for async function. Resolves some false positives
+  with async functions and ``overload``. (#577)
 
 6.1.1 - May 17th, 2021
 ---------------------------

src/pydocstyle/parser.py

@@ -492,6 +492,7 @@ def parse_decorators(self):
                 self.current.value,
             )
             if self.current.kind == tk.NAME and self.current.value in [
+                'async',
                 'def',
                 'class',
             ]:

src/tests/test_decorators.py

@@ -130,6 +130,21 @@ def some_method(self):
         assert 'first_decorator' == decorators[0].name
         assert '' == decorators[0].arguments
 
+    def test_parse_async_function_decorator(self):
+        """Decorators for async functions are also accumulated."""
+        code = textwrap.dedent("""\
+            @first_decorator
+            async def some_method(self):
+                pass
+        """)
+
+        module = checker.parse(io.StringIO(code), 'dummy.py')
+        decorators = module.children[0].decorators
+
+        assert 1 == len(decorators)
+        assert 'first_decorator' == decorators[0].name
+        assert '' == decorators[0].arguments
+
     def test_parse_method_nested_decorator(self):
         """Method decorators are accumulated for nested methods."""
         code = textwrap.dedent("""\

src/tests/test_integration.py

@@ -621,6 +621,36 @@ def overloaded_func(a):
     assert 'D103' not in out
 
 
+def test_overload_async_function(env):
+    """Async functions decorated with @overload trigger D418 error."""
+    with env.open('example.py', 'wt') as example:
+        example.write(textwrap.dedent('''\
+        from typing import overload
+
+
+        @overload
+        async def overloaded_func(a: int) -> str:
+            ...
+
+
+        @overload
+        async def overloaded_func(a: str) -> str:
+            """Foo bar documentation."""
+            ...
+
+
+        async def overloaded_func(a):
+            """Foo bar documentation."""
+            return str(a)
+
+        '''))
+    env.write_config(ignore="D100")
+    out, err, code = env.invoke()
+    assert code == 1
+    assert 'D418' in out
+    assert 'D103' not in out
+
+
 def test_overload_method(env):
     """Methods decorated with @overload trigger D418 error."""
     with env.open('example.py', 'wt') as example:
@@ -714,6 +744,36 @@ def overloaded_func(a):
     assert code == 0
 
 
+def test_overload_async_function_valid(env):
+    """Valid case for overload decorated async functions.
+
+    This shouldn't throw any errors.
+    """
+    with env.open('example.py', 'wt') as example:
+        example.write(textwrap.dedent('''\
+        from typing import overload
+
+
+        @overload
+        async def overloaded_func(a: int) -> str:
+            ...
+
+
+        @overload
+        async def overloaded_func(a: str) -> str:
+            ...
+
+
+        def overloaded_func(a):
+            """Foo bar documentation."""
+            return str(a)
+
+        '''))
+    env.write_config(ignore="D100")
+    out, err, code = env.invoke()
+    assert code == 0
+
+
 def test_overload_nested_function(env):
     """Nested functions decorated with @overload trigger D418 error."""
     with env.open('example.py', 'wt') as example: