Add warning on admin dashboard if production env is configured to send email through gmail

spec/models/admin_dashboard_data_spec.rb

@@ -121,9 +121,32 @@ describe AdminDashboardData do
     end
   end
 
+  describe 'send_email_with_gmail_check' do
+    subject { AdminDashboardData.new.send_email_with_gmail_check }
+
+    it 'returns nil if gmail.com is not in the smtp_settings address' do
+      ActionMailer::Base.stubs(:smtp_settings).returns({address: 'mandrillapp.com'})
+      expect(subject).to be_nil
+    end
+
+    context 'gmail.com is in the smtp_settings address' do
+      before { ActionMailer::Base.stubs(:smtp_settings).returns({address: 'smtp.gmail.com'}) }
+
+      it 'returns nil in development env' do
+        Rails.stubs(:env).returns('development')
+        expect(subject).to be_nil
+      end
+
+      it 'returns a string when in production env' do
+        Rails.stubs(:env).returns('production')
+        expect(subject).to_not be_nil
+      end
+    end
+  end
+
   describe 'auth_config_checks' do
 
-    shared_examples_for 'problem detection for login providers' do
+    shared_examples 'problem detection for login providers' do
       context 'when disabled' do
         it 'returns nil' do
           SiteSetting.stubs(enable_setting).returns(false)
@@ -167,7 +190,7 @@ describe AdminDashboardData do
       let(:enable_setting) { :enable_facebook_logins }
       let(:key) { :facebook_app_id }
       let(:secret) { :facebook_app_secret }
-      it_should_behave_like 'problem detection for login providers'
+      include_examples 'problem detection for login providers'
     end
 
     describe 'twitter' do
@@ -175,7 +198,7 @@ describe AdminDashboardData do
       let(:enable_setting) { :enable_twitter_logins }
       let(:key) { :twitter_consumer_key }
       let(:secret) { :twitter_consumer_secret }
-      it_should_behave_like 'problem detection for login providers'
+      include_examples 'problem detection for login providers'
     end
 
     describe 'github' do
@@ -183,7 +206,7 @@ describe AdminDashboardData do
       let(:enable_setting) { :enable_github_logins }
       let(:key) { :github_client_id }
       let(:secret) { :github_client_secret }
-      it_should_behave_like 'problem detection for login providers'
+      include_examples 'problem detection for login providers'
     end
   end