feat: Add async property for coroutine functions

Feature request: mkdocstrings/mkdocstrings#151.
Pull request: ghpr-65.

src/pytkdocs/loader.py

@@ -91,6 +91,10 @@ def is_function(self) -> bool:
         """Is this node's object a function?"""
         return inspect.isfunction(self.obj)
 
+    def is_coroutine_function(self) -> bool:
+        """Is this node's object a coroutine?"""
+        return inspect.iscoroutinefunction(self.obj)
+
     def is_property(self) -> bool:
         """Is this node's object a property?"""
         return isinstance(self.obj, property)
@@ -460,13 +464,18 @@ def get_function_documentation(self, node: ObjectNode) -> Function:
             self.errors.append(f"Couldn't read source for '{path}': {error}")
             source = None
 
+        properties: List[str] = []
+        if node.is_coroutine_function():
+            properties.append("async")
+
         return Function(
             name=node.name,
             path=node.dotted_path,
             file_path=node.file_path,
             docstring=inspect.getdoc(function),
             signature=signature,
             source=source,
+            properties=properties,
         )
 
     def get_property_documentation(self, node: ObjectNode) -> Attribute:
@@ -664,6 +673,12 @@ def get_method_documentation(self, node: ObjectNode, properties: Optional[List[s
         except TypeError:
             source = None
 
+        if node.is_coroutine_function():
+            if properties is None:
+                properties = ["async"]
+            else:
+                properties.append("async")
+
         return Method(
             name=node.name,
             path=path,

tests/fixtures/asyncio.py

@@ -0,0 +1,6 @@
+class ClassContainingCoroutineMethod:
+    async def coroutine_method(self) -> None:
+        return
+
+async def coroutine_function() -> None:
+    return

tests/test_loader.py

@@ -409,3 +409,31 @@ def test_unwrap_object_with_getattr_method_raising_exception():
     """Try loading an object that defines a `__getattr__` method which raises an exception."""
     loader = Loader()
     loader.get_object_documentation("tests.fixtures.unwrap_getattr_raises")
+
+
+def test_loading_coroutine():
+    """Load documentation for a coroutine."""
+    loader = Loader()
+    obj = loader.get_object_documentation("tests.fixtures.asyncio.coroutine_function")
+    assert "async" in obj.properties
+
+
+def test_loading_coroutine_method():
+    """Load documentation for a coroutine method."""
+    loader = Loader()
+    obj = loader.get_object_documentation("tests.fixtures.asyncio.ClassContainingCoroutineMethod.coroutine_method")
+    assert "async" in obj.properties
+
+
+def test_loading_function_without_async_property():
+    """Load documentation for a function that is not a coroutine."""
+    loader = Loader()
+    obj = loader.get_object_documentation("tests.fixtures.the_package.the_module.the_function")
+    assert "async" not in obj.properties
+
+
+def test_loading_method_without_async_property():
+    """Load documentation for a method that is not a coroutine."""
+    loader = Loader()
+    obj = loader.get_object_documentation("tests.fixtures.the_package.the_module.TheClass.the_method")
+    assert "async" not in obj.properties