F2: Test BatchPublisher (#598)

* Parameterize `PostPublisher`

* Fix class reference

* Drop unused variable

* Test `BatchPublisher`

* Rubocop

Author: dreikanter

app/services/batch_publisher.rb

@@ -4,15 +4,16 @@
 class BatchPublisher
   include Logging
 
-  attr_reader :posts, :freefeed_client
+  attr_reader :posts, :freefeed_client, :publisher_class
 
-  def initialize(posts:, freefeed_client:)
+  def initialize(posts:, freefeed_client:, publisher_class: PostPublisher)
     @posts = posts
     @freefeed_client = freefeed_client
+    @publisher_class = publisher_class
   end
 
   def publish
-    logger.info("publishing #{TextHelpers.pluralize(pending_posts.count, "posts")}")
+    logger.info("publishing #{TextHelpers.pluralize(posts.count, "posts")}")
 
     posts.each do |post|
       logger.info("publishing post: #{post.id}")
@@ -25,7 +26,7 @@ def publish
   def publish_post(post)
     post.with_lock do
       next unless post.reload.enqueued?
-      PostPublisher.new(post: post, freefeed_client: freefeed_client).publish
+      publisher_class.new(post: post, freefeed_client: freefeed_client).publish
     end
   end
 end

app/services/feed_processor.rb

@@ -14,7 +14,7 @@ def initialize(feeds:)
   def perform
     feeds.each do |feed|
       Importer.new(feed).import
-      Publisher.new(posts: feed.posts.pending, freefeed_client: build_freefeed_client).publish
+      BatchPublisher.new(posts: feed.posts.pending, freefeed_client: build_freefeed_client).publish
 
       # TBD: Handle errors
     end

spec/services/batch_publisher_spec.rb

@@ -1 +1,87 @@
-require "rails_helper"
+RSpec.describe BatchPublisher do
+  subject(:batch_publisher) do
+    described_class.new(
+      posts: [first_post, second_post],
+      freefeed_client: freefeed_client,
+      publisher_class: publisher_class
+    )
+  end
+
+  let(:freefeed_client) do
+    Freefeed::Client.new(
+      token: "TEST_TOKEN",
+      base_url: "https://freefeed.test"
+    )
+  end
+
+  let(:publisher_class) { class_double(PostPublisher) }
+  let(:publisher_instance) { instance_double(PostPublisher) }
+
+  let(:first_post) { create(:post, state: "enqueued", feed: feed) }
+  let(:second_post) { create(:post, state: "enqueued", feed: feed) }
+  let(:feed) { create(:feed) }
+
+  describe "#publish" do
+    before do
+      allow(publisher_class).to receive(:new)
+        .with(post: anything, freefeed_client: freefeed_client)
+        .and_return(publisher_instance)
+
+      allow(publisher_instance).to receive(:publish)
+    end
+
+    context "when posts are enqueued" do
+      it "attempts to publish all enqueued posts" do
+        allow(publisher_class).to receive(:new)
+          .with(post: first_post, freefeed_client: freefeed_client)
+          .and_return(publisher_instance)
+
+        allow(publisher_class).to receive(:new)
+          .with(post: second_post, freefeed_client: freefeed_client)
+          .and_return(publisher_instance)
+
+        expect(publisher_instance).to receive(:publish).twice
+
+        batch_publisher.publish
+      end
+    end
+
+    context "when some posts are not enqueued" do
+      let(:second_post) { create(:post, state: "draft", feed: feed) }
+
+      it "only publishes enqueued posts" do
+        expect(publisher_class).to receive(:new)
+          .with(post: first_post, freefeed_client: freefeed_client)
+          .once
+          .and_return(publisher_instance)
+
+        expect(publisher_instance).to receive(:publish).once
+
+        expect(publisher_class).not_to receive(:new)
+          .with(post: second_post, freefeed_client: freefeed_client)
+
+        batch_publisher.publish
+      end
+    end
+
+    context "when post state changes during processing" do
+      it "skips posts that are no longer enqueued" do
+        allow(first_post).to receive(:reload).and_return(
+          create(:post, state: "published", feed: feed)
+        )
+
+        expect(publisher_class).not_to receive(:new)
+          .with(post: first_post, freefeed_client: freefeed_client)
+
+        expect(publisher_class).to receive(:new)
+          .with(post: second_post, freefeed_client: freefeed_client)
+          .once
+          .and_return(publisher_instance)
+
+        expect(publisher_instance).to receive(:publish).once
+
+        batch_publisher.publish
+      end
+    end
+  end
+end

spec/services/post_publisher_spec.rb

@@ -1,6 +1,4 @@
 RSpec.describe PostPublisher do
-  subject(:service) { described_class.new(post: post, freefeed_client: freefeed_client) }
-
   let(:freefeed_client) do
     Freefeed::Client.new(
       token: "TEST_TOKEN",