Fixes issue with @Inject and docstring

Beforehand, we broke if there was a docstring in an inject decorated
function. This was due to having a placeholder function name, as it
delegated to `@parameterize`. The best fix would be to not have it
delegate (this is a bit of a hack), but for now we make it not break.

hamilton/function_modifiers/base.py

@@ -605,7 +605,6 @@ def filter_config(config: Dict[str, Any], decorator: NodeTransformLifecycle) ->
     """
     config_required = decorator.required_config()
     config_optional_with_defaults = decorator.optional_config()
-    print(decorator, config_required, config_optional_with_defaults)
     return resolve_config(decorator.name, config, config_required, config_optional_with_defaults)
 
 

hamilton/function_modifiers/expanders.py

@@ -276,7 +276,9 @@ def validate(self, fn: Callable):
         try:
             for output_name, mappings in self.parameterization.items():
                 # TODO -- separate out into the two dependency-types
-                self.format_doc_string(fn.__doc__, output_name)
+                if output_name == self.PLACEHOLDER_PARAM_NAME:
+                    output_name = fn.__name__
+                self.format_doc_string(fn, output_name)
         except KeyError as e:
             raise base.InvalidDecoratorException(
                 f"Function docstring templating is incorrect. "

tests/function_modifiers/test_expanders.py

@@ -706,6 +706,28 @@ def foo(x: Dict) -> int:
         annotation.validate(foo)
 
 
+def test_inject_validate_with_docstring():
+    def foo(x: int) -> int:
+        """Docstring..."""
+        return x
+
+    annotation = function_modifiers.inject(x=value(1))
+    annotation.validate(foo)
+    (node_,) = annotation.expand_node(node.Node.from_fn(foo), {}, foo)
+    assert node_.documentation == "Docstring..."
+
+
+def test_inject_validate_with_docstring_replacement():
+    def foo(x: int) -> int:
+        """Docstring. x={x} is injected."""
+        return x
+
+    annotation = function_modifiers.inject(x=value(1))
+    annotation.validate(foo)
+    (node_,) = annotation.expand_node(node.Node.from_fn(foo), {}, foo)
+    assert node_.documentation == "Docstring. x=1 is injected."
+
+
 def test_parameterize_repeated_sources():
     def foo(x: int, y: int) -> int:
         return x + y