js-on-sx: runner inlines small upstream harness includes per-test (allowlisted)

lib/js/test262-runner.py

@@ -1060,11 +1060,45 @@ def _worker_run(args):
 # ---------------------------------------------------------------------------
 
 
+_HARNESS_INCLUDE_CACHE: dict = {}
+
+# Only inline these small harness files per-test. Large ones like propertyHelper.js
+# multiply js-eval/JIT cost by ~5-10x and push tests over the per-test timeout.
+_INLINE_INCLUDES = {"nans.js", "sta.js", "byteConversionValues.js", "compareArray.js"}
+
+
+def _load_harness_include(name: str) -> str:
+    """Read an upstream harness include file (e.g. nans.js).
+    Returns empty string if the file isn't present.
+    """
+    if name in _HARNESS_INCLUDE_CACHE:
+        return _HARNESS_INCLUDE_CACHE[name]
+    path = HARNESS_DIR / name
+    try:
+        src = path.read_text()
+    except OSError:
+        src = ""
+    _HARNESS_INCLUDE_CACHE[name] = src
+    return src
+
+
 def assemble_source(t):
     """Return JS source to feed to js-eval. Harness is preloaded, so we only
-    append the test source (plus negative-test prep if needed).
+    append the test source (plus a small allowlist of per-test includes).
     """
-    return t.src
+    if not getattr(t.fm, "includes", None):
+        return t.src
+    parts = []
+    for inc in t.fm.includes:
+        if inc not in _INLINE_INCLUDES:
+            continue
+        chunk = _load_harness_include(inc)
+        if chunk:
+            parts.append(chunk)
+    if not parts:
+        return t.src
+    parts.append(t.src)
+    return "\n".join(parts)
 
 
 def aggregate(results):
@@ -1242,7 +1276,7 @@ def main(argv):
     shards = [[] for _ in range(n_workers)]
     for i, t in enumerate(tests):
         shards[i % n_workers].append(
-            (t.rel, t.category, t.src, t.fm.negative_phase, t.fm.negative_type)
+            (t.rel, t.category, assemble_source(t), t.fm.negative_phase, t.fm.negative_type)
         )
 
     t_run_start = time.monotonic()