Introduce BlogPost::Writer

This module is only responsible for picking a BlogPost writer given the
environment variables..

lib/gold_miner.rb

@@ -22,20 +22,7 @@ def convert_messages_to_blogpost(channel, messages, blog_post_builder: GoldMiner
       slack_channel: channel,
       messages: messages,
       since: Helpers::Time.last_friday,
-      writer: blog_post_writer
+      writer: BlogPost::Writer.from_env
     )
   end
-
-  private
-
-  def blog_post_writer
-    if ENV["OPEN_AI_API_TOKEN"]
-      GoldMiner::BlogPost::OpenAiWriter.new(
-        open_ai_api_token: ENV["OPEN_AI_API_TOKEN"],
-        fallback_writer: GoldMiner::BlogPost::SimpleWriter.new
-      )
-    else
-      GoldMiner::BlogPost::SimpleWriter.new
-    end
-  end
 end

lib/gold_miner/blog_post/writer.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+module GoldMiner
+  class BlogPost
+    module Writer
+      def self.from_env
+        if ENV["OPEN_AI_API_TOKEN"]
+          GoldMiner::BlogPost::OpenAiWriter.new(
+            open_ai_api_token: ENV["OPEN_AI_API_TOKEN"],
+            fallback_writer: GoldMiner::BlogPost::SimpleWriter.new
+          )
+        else
+          GoldMiner::BlogPost::SimpleWriter.new
+        end
+      end
+    end
+  end
+end

spec/gold_miner/blog_post/writer_spec.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+RSpec.describe GoldMiner::BlogPost::Writer do
+  describe ".from_env" do
+    context "when OPEN_AI_API_TOKEN env var is set" do
+      it "returns an OpenAI writer" do
+        with_env("OPEN_AI_API_TOKEN" => "test-token") do
+          writer = described_class.from_env
+
+          expect(writer).to be_a GoldMiner::BlogPost::OpenAiWriter
+        end
+      end
+    end
+    context "when OPEN_AI_API_TOKEN env var is not set" do
+      it "returns a Simple writer" do
+        with_env("OPEN_AI_API_TOKEN" => nil) do
+          writer = described_class.from_env
+
+          expect(writer).to be_a GoldMiner::BlogPost::SimpleWriter
+        end
+      end
+    end
+  end
+end

spec/gold_miner_spec.rb

@@ -80,15 +80,4 @@
   it "has a version number" do
     expect(GoldMiner::VERSION).not_to be nil
   end
-
-  private
-
-  def with_env(env)
-    original_env = ENV.to_hash
-    ENV.update(env)
-
-    yield
-  ensure
-    ENV.replace(original_env)
-  end
 end

spec/support/env_helpers.rb

@@ -0,0 +1,14 @@
+module EnvHelpers
+  def with_env(env)
+    original_env = ENV.to_hash
+    ENV.update(env)
+
+    yield
+  ensure
+    ENV.replace(original_env)
+  end
+end
+
+RSpec.configure do |config|
+  config.include EnvHelpers
+end