Add test for `Services::Tumblr`

spec/models/services/tumblr_spec.rb

@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe Services::Tumblr do
+  describe "#post" do
+    let(:user) { FactoryBot.create(:user) }
+    let(:service) { Services::Tumblr.create(user: user) }
+    let(:answer) { FactoryBot.create(:answer, user: user,
+                                     content: 'a' * 255,
+                                     question_content: 'q' * 255) }
+    let(:tumblr_client) { instance_double(Tumblr::Client) }
+
+    before do
+      allow(Tumblr::Client).to receive(:new).and_return(tumblr_client)
+      allow(tumblr_client).to receive(:text)
+      stub_const("APP_CONFIG", {
+        'hostname' => 'example.com',
+        'anonymous_name' => 'Anonymous',
+        'https' => true,
+        'items_per_page' => 5,
+        'sharing' => {
+          'tumblr' => {
+            'consumer_key' => 'AAA',
+          }
+        }
+      })
+    end
+    
+    it "posts a text-post" do
+      answer.question.content = 'Why are raccoons so good?'
+      answer.question.author_is_anonymous = true
+      answer.question.save!
+      answer.content = 'Because they are good cunes.'
+      answer.save!
+
+      service.post(answer)
+
+      expect(tumblr_client).to have_received(:text).with(
+        service.uid,
+        title: 'Anonymous asked: Why are raccoons so good?',
+        body: "Because they are good cunes.\n\n[Smile or comment on the answer here](https://example.com/#{user.screen_name}/a/#{answer.id})",
+        format: 'markdown',
+        tweet: 'off'
+      )
+    end
+  end
+end