refactor: refactors message dequeueing (#2810)

spec/lib/message_dequeuer/state_spec.rb

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+module MessageDequeuer
+
+  RSpec.describe State do
+    subject(:state) { described_class.new }
+
+    describe "#send_result" do
+      it "can be get and set" do
+        result = instance_double(Postal::SendResult)
+        state.send_result = result
+        expect(state.send_result).to be result
+      end
+    end
+
+    describe "#sender_for" do
+      it "returns a instance of the given sender initialized with the args" do
+        sender = state.sender_for(Postal::HTTPSender, "1234")
+        expect(sender).to be_a Postal::HTTPSender
+      end
+
+      it "returns a cached sender on subsequent calls" do
+        sender = state.sender_for(Postal::HTTPSender, "1234")
+        expect(state.sender_for(Postal::HTTPSender, "1234")).to be sender
+      end
+    end
+
+    describe "#finished" do
+      it "calls finish on all cached senders" do
+        sender1 = state.sender_for(Postal::HTTPSender, "1234")
+        sender2 = state.sender_for(Postal::HTTPSender, "4444")
+        expect(sender1).to receive(:finish)
+        expect(sender2).to receive(:finish)
+
+        state.finished
+      end
+    end
+  end
+
+end