Fix when resque failure backend is already multiple

CHANGELOG.md

@@ -1,6 +1,14 @@
 Changelog
 =========
 
+## TBD
+
+### Fixes
+
+* Fix Resque integration when failure backend is already `Resque::Failure::Multiple`
+  | [#803](https://github.com/bugsnag/bugsnag-ruby/pull/803)
+  | [sj26](https://github.com/sj26)
+
 ## v6.26.0 (19 July 2023)
 
 ### Enhancements

features/fixtures/rails_integrations/app/config/application.rb

@@ -1,3 +1,14 @@
+# reproduce #803 by setting Resque's backend to 'Multiple' before our Resque
+# integration runs
+# see https://github.com/bugsnag/bugsnag-ruby/pull/803
+require "resque"
+require "resque/failure/redis"
+require "resque/failure/multiple"
+
+Resque::Failure::Multiple.classes = [Resque::Failure::Redis]
+Resque::Failure.backend = Resque::Failure::Multiple
+# end #803 reproduction
+
 require_relative 'boot'
 
 require "rails"

lib/bugsnag/integrations/resque.rb

@@ -21,7 +21,7 @@ def self.add_failure_backend
       return if ::Resque::Failure.backend == self
 
       # Ensure resque is using a "Multiple" failure backend
-      unless ::Resque::Failure.backend < ::Resque::Failure::Multiple
+      unless ::Resque::Failure.backend <= ::Resque::Failure::Multiple
         original_backend = ::Resque::Failure.backend
         ::Resque::Failure.backend = ::Resque::Failure::Multiple
         ::Resque::Failure.backend.classes ||= []

spec/integrations/resque_spec.rb

@@ -31,7 +31,7 @@ def require(path)
     #Auto-load failure backend
     backend = double('backend')
     allow(::Resque::Failure).to receive(:backend).and_return(backend)
-    expect(backend).to receive(:<).and_return(nil)
+    expect(backend).to receive(:<=).and_return(nil)
     expect(::Resque::Failure).to receive(:backend=).with(::Resque::Failure::Multiple)
     classes = double('classes')
     allow(backend).to receive(:classes).and_return(classes)