From abd388c07c993d20600ce048b9434dc0532cbbae Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jukka=20Jyl=C3=A4nki?= <jujjyl@gmail.com>
Date: Fri, 3 Oct 2025 20:28:45 +0300
Subject: [PATCH] Add comment about minimum Firefox version required to run
 parallel test harness.

---
 test/common.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/test/common.py b/test/common.py
index b16d2cceeef0a..d5f6b70456d26 100644
--- a/test/common.py
+++ b/test/common.py
@@ -116,6 +116,9 @@ def configure(data_dir):
     """Chrome has no special configuration step."""
 
 
+# N.b. The earliest Firefox version that can run multithreaded browser harness
+# is Firefox 67. If you need to test earlier Firefox versions, use EMTEST_CORES=1
+# environment variable to revert to the single-threaded browser harness.
 class FirefoxConfig:
   data_dir_flag = '-profile '
   default_flags = ('-new-instance',)