From b0c2a07190b94be9ff0b3af1d970a0224dc0ce3b Mon Sep 17 00:00:00 2001
From: Shang Chieh Tseng <shangchieh.tseng@tsengsyu.com>
Date: Wed, 17 Dec 2025 16:08:01 +0800
Subject: [PATCH] Fix JSON output contamination in test runner

Change judge.ts progress message from console.log (stdout) to
process.stderr.write (stderr) to prevent 'Judging batch...' message
from contaminating JSON output when using --output json flag.
---
 tests/src/judge.ts | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tests/src/judge.ts b/tests/src/judge.ts
index 8d26ded8..8aafc559 100644
--- a/tests/src/judge.ts
+++ b/tests/src/judge.ts
@@ -98,8 +98,9 @@ Respond ONLY with the JSON array, no other text.`;
     // Process in batches
     for (let i = 0; i < results.length; i += this.batchSize) {
       const batch = results.slice(i, i + this.batchSize);
-      console.log(
-        `  Judging batch ${Math.floor(i / this.batchSize) + 1}/${Math.ceil(results.length / this.batchSize)}...`,
+      // Write progress to stderr to avoid contaminating JSON output on stdout
+      process.stderr.write(
+        `  Judging batch ${Math.floor(i / this.batchSize) + 1}/${Math.ceil(results.length / this.batchSize)}...\n`,
       );
 
       try {