Fix indentation error while parsing class methods

docs/release_notes.rst

@@ -15,6 +15,8 @@ Bug Fixes
 
 * Update convention support documentation (#386, #393)
 * Detect inner asynchronous functions for D202 (#467)
+* Fix indentation error while parsing class methods (#441).
+
 
 5.0.2 - January 8th, 2020
 ---------------------------

src/pydocstyle/checker.py

@@ -1007,9 +1007,20 @@ def is_def_arg_private(arg_name):
     """Return a boolean indicating if the argument name is private."""
     return arg_name.startswith("_")
 
-def get_function_args(function_string):
+def get_function_args(function_source):
     """Return the function arguments given the source-code string."""
-    function_arg_node = ast.parse(textwrap.dedent(function_string)).body[0].args
+    # We are stripping the whitespace from the left of the
+    # function source.
+    # This is so that if the docstring has incorrectly
+    # indented lines, which are at a lower indent than the
+    # function source, we still dedent the source correctly
+    # and the AST parser doesn't throw an error.
+    try:
+        function_arg_node = ast.parse(function_source.lstrip()).body[0].args
+    except SyntaxError:
+        # If we still get a syntax error, we don't want the
+        # the checker to crash. Instead we just return a blank list.
+        return []
     arg_nodes = function_arg_node.args
     kwonly_arg_nodes = function_arg_node.kwonlyargs
     return [arg_node.arg for arg_node in chain(arg_nodes, kwonly_arg_nodes)]

src/tests/test_cases/expected.py

@@ -4,13 +4,13 @@ class Expectation:
     def __init__(self):
         self.expected = set()
 
-    def expect(self, *args, arg_count=0):
+    def expect(self, *args, arg_count=0, func_name=""):
         """Decorator that expects a certain PEP 257 violation."""
         # The `arg_count` parameter helps the decorator
         # with functions that have positional arguments.
         if len(args) == 1:
             def decorate(f):
-                self.expected.add((f.__name__, args[0]))
+                self.expected.add((func_name or f.__name__, args[0]))
                 f(*[None]*arg_count)
                 return f
             return decorate

src/tests/test_cases/sections.py

@@ -274,6 +274,25 @@ def missing_colon_google_style_section():  # noqa: D406, D407
     """
 
 
+@expect("D417: Missing argument descriptions in the docstring "
+        "(argument(s) y are missing descriptions in "
+        "'bar' docstring)", func_name="bar")
+def _test_nested_functions():
+    x = 1
+
+    def bar(y=2):  # noqa: D207, D213, D406, D407
+        """Nested function test for docstrings.
+
+        Will this work when referencing x?
+
+        Args:
+            x: Test something
+that is broken.
+
+        """
+        print(x)
+
+
 @expect(_D213)
 @expect("D417: Missing argument descriptions in the docstring "
         "(argument(s) y are missing descriptions in "
@@ -340,13 +359,15 @@ def test_missing_args_static_method(a, x, y, _test, z=3):  # noqa: D213, D407
 @expect("D417: Missing argument descriptions in the docstring "
         "(argument(s) y are missing descriptions in "
         "'test_missing_numpy_args' docstring)")
+@expect("D207: Docstring is under-indented")
 def test_missing_numpy_args(_private_arg=0, x=1, y=2):  # noqa: D406, D407
     """Toggle the gizmo.
 
     Parameters
     ----------
     x : int
-        The greatest integer.
+        The greatest integer in the history \
+of the entire world.
 
     """
 
@@ -425,3 +446,20 @@ def test_mixing_numpy_and_google(danger):  # noqa: D213
             Zoneeeeee!
 
         """
+
+
+class TestIncorrectIndent:  # noqa: D203
+    """Test class."""
+
+    @expect("D417: Missing argument descriptions in the docstring "
+            "(argument(s) y are missing descriptions in "
+            "'test_incorrect_indent' docstring)", arg_count=3)
+    def test_incorrect_indent(self, x=1, y=2):  # noqa: D207, D213, D407
+        """Reproducing issue #437.
+
+Testing this incorrectly indented docstring.
+
+        Args:
+            x: Test argument.
+
+        """