fix(wpt-cross): model nosniff script fixture

moli-benchmark/moli_benchmark/wpt_cross/server.py

@@ -1246,6 +1246,24 @@ def _inspect_headers_response_headers(
     return response_headers
 
 
+def _nosniff_javascript_response(query: str) -> tuple[str | None, bytes]:
+    """Model fetch/nosniff/resources/js.py's MIME-controlled script body."""
+
+    params = parse_qsl(query, keep_blank_values=True)
+    outcome = next(
+        (value for name, value in params if name == "outcome"),
+        "f",
+    )
+    content_type = next(
+        (value for name, value in params if name == "type"),
+        None,
+    )
+    type_label = content_type if content_type is not None else "Content-Type missing"
+    result_call = "log('FAIL: " + type_label + "')" if outcome == "f" else "p()"
+    body = ("// nothing to see here\n" + result_call).encode()
+    return content_type, body
+
+
 def _url_host_literal(hostname: str) -> str:
     if hostname.startswith("[") and hostname.endswith("]"):
         return hostname
@@ -2089,6 +2107,9 @@ def _make_handler(
                     status_code=pipe_status_code or 200,
                 )
                 return
+            if path == "/fetch/nosniff/resources/js.py":
+                self._serve_nosniff_javascript(parsed.query, emit_body=emit_body)
+                return
             if path == (
                 "/html/semantics/scripting-1/the-script-element/module/"
                 "resources/delayed-modulescript.py"
@@ -2986,6 +3007,20 @@ def _make_handler(
                 extra_headers=[("X-Request-Method", self.command)],
             )
 
+        def _serve_nosniff_javascript(self, query: str, *, emit_body: bool) -> None:
+            content_type, body = _nosniff_javascript_response(query)
+            self.send_response(200)
+            self.send_header("X-Content-Type-Options", "nosniff")
+            self.send_header("Content-Length", str(len(body)))
+            if content_type is not None:
+                self.send_header("Content-Type", content_type)
+            self.end_headers()
+            if emit_body:
+                try:
+                    self.wfile.write(body)
+                except (BrokenPipeError, ConnectionResetError):
+                    return
+
         def _send_bytes(
             self,
             content_type: str | None,

moli-benchmark/tests/test_wpt_cross.py

@@ -124,8 +124,9 @@ from moli_benchmark.wpt_cross.server import (
     _inject_bench_report_bridge_config,
     _host_header_hostname,
     _headers_include,
-    _normalize_harness_case_key,
     _inspect_headers_response_headers,
+    _normalize_harness_case_key,
+    _nosniff_javascript_response,
     _needs_wpt_template_substitution,
     _legacy_wpt_resource_alias,
     _pipe_response_header_operations,
@@ -4174,6 +4175,55 @@ test(() => {}, "ok");
                         "x-request-referer, x-request-origin",
                     )
 
+    def test_fixture_server_models_fetch_nosniff_javascript_handler(self) -> None:
+        self.assertEqual(
+            _nosniff_javascript_response(""),
+            (
+                None,
+                b"// nothing to see here\nlog('FAIL: Content-Type missing')",
+            ),
+        )
+        self.assertEqual(
+            _nosniff_javascript_response("type=text%2Fjavascript&outcome=p"),
+            ("text/javascript", b"// nothing to see here\np()"),
+        )
+
+        with tempfile.TemporaryDirectory() as root:
+            root_path = Path(root)
+            (root_path / "resources").mkdir()
+            (root_path / "resources" / "testharness.js").write_text(
+                "// testharness", encoding="utf-8"
+            )
+            with WptFixtureServer(root_path) as server:
+                base_url = f"{server.base_url}/fetch/nosniff/resources/js.py"
+                responses = []
+                for query in (
+                    "",
+                    "?type=",
+                    "?type=text%2Fjavascript&outcome=p",
+                ):
+                    with urlopen(base_url + query, timeout=2) as response:
+                        responses.append(
+                            (
+                                response.headers.get("Content-Type"),
+                                response.headers["X-Content-Type-Options"],
+                                response.read(),
+                            )
+                        )
+
+        self.assertEqual(
+            responses,
+            [
+                (
+                    None,
+                    "nosniff",
+                    b"// nothing to see here\nlog('FAIL: Content-Type missing')",
+                ),
+                ("", "nosniff", b"// nothing to see here\nlog('FAIL: ')"),
+                ("text/javascript", "nosniff", b"// nothing to see here\np()"),
+            ],
+        )
+
     def test_fixture_server_models_xhr_delay_py_methods(self) -> None:
         with tempfile.TemporaryDirectory() as root:
             root_path = Path(root)