Support testing by mocking MockRedis#evalsha

lib/idempotency/testing/rspec/helpers.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+require 'idempotency/cache'
+
+class Idempotency
+  module Testing
+    module RSpec
+      module Helpers
+        def self.included(_base)
+          return unless defined?(MockRedis)
+
+          MockRedis.class_eval do
+            def evalsha(sha, keys:, argv:)
+              return unless sha == Idempotency::Cache::COMPARE_AND_DEL_SCRIPT_SHA
+
+              value = argv[0]
+              cached_value = get(keys[0])
+
+              if value == cached_value
+                del(keys[0])
+                value
+              else
+                cached_value
+              end
+            end
+          end
+        end
+      end
+    end
+  end
+end