fix(hansbug): remove named temporary file when rendering images

test/entry/cli/test_graph.py

@@ -245,6 +245,6 @@ class TestEntryCliGraph:
                                               f'The output is:\n{result.output}'
                 assert os.path.exists('test_graph.svg')
                 if OS.windows:
-                    assert os.path.getsize('test_graph.svg') <= 2000
+                    assert 5000 <= os.path.getsize('test_graph.svg') <= 6500
                 else:
-                    assert os.path.getsize('test_graph.svg') <= 1000
+                    assert 500 <= os.path.getsize('test_graph.svg') <= 1000

treevalue/entry/cli/graph.py

@@ -60,9 +60,11 @@ def _save_source_code(g: Digraph, path: str):
         file.write(g.source)
 
 
+# Do not reopen an opened file in windows, it may cause PermissionDenied
+# See: https://stackoverflow.com/a/23212515/6995899
 def _save_image(g: Digraph, path: str, fmt: str):
-    with tempfile.NamedTemporaryFile() as tmpfile:
-        svg_file = g.render(tmpfile.name, format=fmt)
+    with tempfile.TemporaryDirectory() as tmpdir:
+        svg_file = g.render(os.path.join(tmpdir, 'source.gv'), format=fmt)
         shutil.copy(svg_file, path)