1 files changed, 18 insertions, 0 deletions
diff --git a/cli/js/tests/test_util.ts b/cli/js/tests/test_util.ts
index 980d32bac..347a2204e 100644
--- a/cli/js/tests/test_util.ts
+++ b/cli/js/tests/test_util.ts
@@ -359,3 +359,21 @@ unitTest(
     });
   }
 );
+function* portIterator(): IterableIterator<number> {
+  // use 49152 ~ 55000 for js/cli (rest are for std)
+  let i = 49152;
+  while (true) {
+    yield i;
+    i++;
+    if (i > 55000) {
+      i = 55000;
+    }
+  }
+}
+const it = portIterator();
+/** Obtain (maybe) safe port number for net tests */
+export function randomPort(): number {
+  const { value } = it.next();
+  assert(value != null);
+  return value;
+}