From a69349171a454a12d9c584d55ace8f00cef49ab6 Mon Sep 17 00:00:00 2001
From: Matt Dale <9760375+matthewdale@users.noreply.github.com>
Date: Mon, 30 Sep 2024 18:24:19 -0700
Subject: [PATCH] Assign Github PR reviews in round-robin order. (#510)

---
 .evergreen/github_app/assign-reviewer.mjs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/.evergreen/github_app/assign-reviewer.mjs b/.evergreen/github_app/assign-reviewer.mjs
index 6e71fb2b..c8977c24 100644
--- a/.evergreen/github_app/assign-reviewer.mjs
+++ b/.evergreen/github_app/assign-reviewer.mjs
@@ -74,7 +74,11 @@ for (let line of reviewersSource.split('\n')) {
     }
     reviewers.push(line);
 }
-const reviewer = reviewers[Math.floor(Math.random() * reviewers.length)]
+// Use the Github PR number to select the next reviewer in round-robin order. We
+// assume that Github PR numbers are sequential and that the order of reviewer
+// names is consistent across runs. Note that Github Issues must be disabled
+// because they share the same number sequence with Github PRs.
+const reviewer = reviewers[number % reviewers.length];
 
 console.log("Assigning reviewer to PR...");
 resp = await octokit.request("POST /repos/{owner}/{repo}/pulls/{number}/requested_reviewers", {