Feature: Slack integration (#783)

- Integrations architecture
- Slack integration

spec/requests/api/v1/integrations/webhooks_request_spec.rb

@@ -0,0 +1,15 @@
+require 'rails_helper'
+
+RSpec.describe 'Api::V1::Integrations::Webhooks', type: :request do
+  describe 'POST /api/v1/integrations/webhooks' do
+    it 'consumes webhook' do
+      builder = Integrations::Slack::IncomingMessageBuilder.new({})
+      builder.stub(:perform) { true }
+
+      expect(Integrations::Slack::IncomingMessageBuilder).to receive(:new).and_return(builder)
+
+      post '/api/v1/integrations/webhooks', params: {}
+      expect(response).to have_http_status(:success)
+    end
+  end
+end