From d282ebf9bd58acb7f394e2ec0dadab984f678a2e Mon Sep 17 00:00:00 2001
From: Christian Bruckmayer <christian.bruckmayer@shopify.com>
Date: Tue, 27 Aug 2024 13:39:26 +0100
Subject: [PATCH] Raise error when progress is negative

---
 ruby/lib/ci/queue/redis/base.rb | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/ruby/lib/ci/queue/redis/base.rb b/ruby/lib/ci/queue/redis/base.rb
index 750b729d..d4debe23 100644
--- a/ruby/lib/ci/queue/redis/base.rb
+++ b/ruby/lib/ci/queue/redis/base.rb
@@ -133,8 +133,12 @@ def to_a
           end.flatten.reverse.map { |k| index.fetch(k) }
         end
 
+        ImplausibleProgress = Class.new(StandardError)
+
         def progress
-          total - size
+          result = total - size
+          raise ImplausibleProgress, "Progress cannot be negative (#{result} (#{total} - #{size}))" if result < 0
+          result
         end
 
         def wait_for_master(timeout: 30)