--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/test/test-process-priority.c	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,83 @@
+/* Copyright libuv contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "uv.h"
+#include "task.h"
+
+
+TEST_IMPL(process_priority) {
+  int priority;
+  int r;
+  int i;
+
+#if defined(__MVS__)
+  if (uv_os_setpriority(0, 0) == UV_ENOSYS)
+    RETURN_SKIP("functionality not supported on zOS");
+#endif
+
+  /* Verify that passing a NULL pointer returns UV_EINVAL. */
+  r = uv_os_getpriority(0, NULL);
+  ASSERT_EQ(r, UV_EINVAL);
+
+  /* Verify that all valid values work. */
+  for (i = UV_PRIORITY_HIGHEST; i <= UV_PRIORITY_LOW; i++) {
+    r = uv_os_setpriority(0, i);
+
+    /* If UV_EACCES is returned, the current user doesn't have permission to
+       set this specific priority. */
+    if (r == UV_EACCES)
+      continue;
+
+    ASSERT_OK(r);
+    ASSERT_OK(uv_os_getpriority(0, &priority));
+
+    /* Verify that the priority values match on Unix, and are range mapped
+       on Windows. */
+#ifndef _WIN32
+    ASSERT_EQ(priority, i);
+#else
+    /* On Windows, only elevated users can set UV_PRIORITY_HIGHEST. Other
+       users will silently be set to UV_PRIORITY_HIGH. */
+    if (i < UV_PRIORITY_HIGH)
+      ASSERT(priority == UV_PRIORITY_HIGHEST || priority == UV_PRIORITY_HIGH);
+    else if (i < UV_PRIORITY_ABOVE_NORMAL)
+      ASSERT_EQ(priority, UV_PRIORITY_HIGH);
+    else if (i < UV_PRIORITY_NORMAL)
+      ASSERT_EQ(priority, UV_PRIORITY_ABOVE_NORMAL);
+    else if (i < UV_PRIORITY_BELOW_NORMAL)
+      ASSERT_EQ(priority, UV_PRIORITY_NORMAL);
+    else if (i < UV_PRIORITY_LOW)
+      ASSERT_EQ(priority, UV_PRIORITY_BELOW_NORMAL);
+    else
+      ASSERT_EQ(priority, UV_PRIORITY_LOW);
+#endif
+
+    /* Verify that the current PID and 0 are equivalent. */
+    ASSERT_OK(uv_os_getpriority(uv_os_getpid(), &r));
+    ASSERT_EQ(priority, r);
+  }
+
+  /* Verify that invalid priorities return UV_EINVAL. */
+  ASSERT_EQ(uv_os_setpriority(0, UV_PRIORITY_HIGHEST - 1), UV_EINVAL);
+  ASSERT_EQ(uv_os_setpriority(0, UV_PRIORITY_LOW + 1), UV_EINVAL);
+
+  return 0;
+}