Fixes regression for visualization stripping path

Viz would strip paths like `./foo/bar/dag.png` to just `dag.png`.

This fixes that.

examples/hello_world/my_script.py

@@ -33,12 +33,11 @@
 print(df.to_string())
 
 # To visualize do `pip install "sf-hamilton[visualization]"` if you want these to work
-dr.visualize_execution(output_columns, "./my_dag.dot", {"format": "png"})
+dr.visualize_execution(output_columns, "./my_dag.png")
 dr.visualize_path_between(
     "spend_mean",
     "spend_zero_mean_unit_variance",
-    "./a_path.dot",
-    {"format": "png"},
+    "./a_path.png",
     strict_path_visualization=False,
 )
-# dr.display_all_functions("./my_full_dag.dot", {"format": "png"})
+dr.display_all_functions("./my_full_dag.png")

hamilton/graph.py

@@ -8,7 +8,7 @@
 
 import inspect
 import logging
-import pathlib
+import os.path
 import uuid
 from enum import Enum
 from types import ModuleType
@@ -856,12 +856,10 @@ def display(
         )
         kwargs = {"view": False, "format": "png"}  # default format = png
         if output_file_path:  # infer format from path
-            suffix = pathlib.Path(output_file_path).suffix
+            output_file_path, suffix = os.path.splitext(output_file_path)
             if suffix != "":
                 inferred_format = suffix.partition(".")[-1]
                 kwargs.update(format=inferred_format)
-                # remove suffix if exist because dot.render() will append the format
-                output_file_path = str(pathlib.Path(output_file_path).stem)
         if render_kwargs and isinstance(render_kwargs, dict):  # accept explicit format
             kwargs.update(render_kwargs)
         if output_file_path:

tests/test_graph.py

@@ -1,4 +1,5 @@
 import inspect
+import os
 import pathlib
 import uuid
 from itertools import permutations
@@ -815,7 +816,7 @@ def _styling_function(*, node, node_class):
 
 @pytest.mark.parametrize("show_legend", [(True), (False)])
 def test_function_graph_display_legend(show_legend: bool, tmp_path: pathlib.Path):
-    dot_file_path = tmp_path / "dag"
+    dot_file_path = tmp_path / "dag.png"
     fg = graph.FunctionGraph.from_modules(tests.resources.dummy_functions, config={"b": 1, "c": 2})
 
     fg.display(
@@ -824,7 +825,8 @@ def test_function_graph_display_legend(show_legend: bool, tmp_path: pathlib.Path
         render_kwargs={"view": False},
         show_legend=show_legend,
     )
-    dot = dot_file_path.open("r").read()
+    dot_file = pathlib.Path(os.path.splitext(str(dot_file_path))[0])
+    dot = dot_file.open("r").read()
 
     found_legend = "cluster__legend" in dot
     assert found_legend is show_legend