FIX: Store custom emojis as uploads.

* Depending on a hardcoded directory was a flawed design
  which made it impossible to debug when custom emojis go
  missing.

spec/integration/admin/emojis_spec.rb

@@ -0,0 +1,76 @@
+require 'rails_helper'
+
+RSpec.describe "Managing custom emojis" do
+  let(:admin) { Fabricate(:admin) }
+  let(:upload) { Fabricate(:upload) }
+
+  before do
+    sign_in(admin)
+  end
+
+  describe "creating a custom emoji" do
+    describe 'when upload is invalid' do
+      it 'should publish the right error' do
+        message = MessageBus.track_publish do
+          post("/admin/customize/emojis.json", {
+            name: 'test',
+            file: fixture_file_upload("#{Rails.root}/spec/fixtures/images/fake.jpg")
+          })
+        end.first
+
+        expect(message.channel).to eq("/uploads/emoji")
+        expect(message.data["errors"]).to eq([I18n.t('upload.images.size_not_found')])
+      end
+    end
+
+    describe 'when emoji name already exists' do
+      it 'should publish the right error' do
+        CustomEmoji.create!(name: 'test', upload: upload)
+
+        message = MessageBus.track_publish do
+          post("/admin/customize/emojis.json", {
+            name: 'test',
+            file: fixture_file_upload("#{Rails.root}/spec/fixtures/images/logo.png")
+          })
+        end.first
+
+        expect(message.channel).to eq("/uploads/emoji")
+
+        expect(message.data["errors"]).to eq([
+          "Name #{I18n.t('activerecord.errors.models.custom_emoji.attributes.name.taken')}"
+        ])
+      end
+    end
+
+    it 'should allow an admin to add a custom emoji' do
+        Emoji.expects(:clear_cache)
+
+        message = MessageBus.track_publish do
+          post("/admin/customize/emojis.json", {
+            name: 'test',
+            file: fixture_file_upload("#{Rails.root}/spec/fixtures/images/logo.png")
+          })
+        end.first
+
+        custom_emoji = CustomEmoji.last
+        upload = custom_emoji.upload
+
+        expect(upload.original_filename).to eq('logo.png')
+        expect(message.channel).to eq("/uploads/emoji")
+        expect(message.data["errors"]).to eq(nil)
+        expect(message.data["name"]).to eq(custom_emoji.name)
+        expect(message.data["url"]).to eq(upload.url)
+    end
+  end
+
+  describe 'deleting a custom emoji' do
+    it 'should allow an admin to delete a custom emoji' do
+      custom_emoji = CustomEmoji.create!(name: 'test', upload: upload)
+      Emoji.clear_cache
+
+      expect { delete "/admin/customize/emojis/#{custom_emoji.name}.json", name: 'test' }
+        .to change { Upload.count }.by(-1)
+        .and change { CustomEmoji.count }.by(-1)
+    end
+  end
+end