fix: normalize JS static MIME types on Windows

Refs #802

tests/test_app_static_mime.py

@@ -0,0 +1,37 @@
+import ast
+import mimetypes
+from pathlib import Path
+
+
+def _load_register_static_mime_types():
+    app_path = Path(__file__).resolve().parents[1] / "app.py"
+    tree = ast.parse(app_path.read_text(encoding="utf-8"), filename=str(app_path))
+    fn = next(node for node in tree.body if isinstance(node, ast.FunctionDef) and node.name == "register_static_mime_types")
+    module = ast.Module(body=[fn], type_ignores=[])
+    ns = {"mimetypes": mimetypes}
+    exec(compile(module, str(app_path), "exec"), ns)
+    return ns["register_static_mime_types"]
+
+
+def test_register_static_mime_types_restores_js_module_types():
+    register_static_mime_types = _load_register_static_mime_types()
+    original_js = mimetypes.types_map.get(".js")
+    original_mjs = mimetypes.types_map.get(".mjs")
+    try:
+        mimetypes.types_map[".js"] = "text/plain"
+        mimetypes.types_map.pop(".mjs", None)
+
+        register_static_mime_types()
+
+        assert mimetypes.types_map[".js"] == "text/javascript"
+        assert mimetypes.types_map[".mjs"] == "application/javascript"
+    finally:
+        if original_js is None:
+            mimetypes.types_map.pop(".js", None)
+        else:
+            mimetypes.types_map[".js"] = original_js
+
+        if original_mjs is None:
+            mimetypes.types_map.pop(".mjs", None)
+        else:
+            mimetypes.types_map[".mjs"] = original_mjs