use custom brand logo in pipeline mails

app/helpers/emails_helper.rb

 module EmailsHelper
+  include AppearancesHelper
+
   # Google Actions
   # https://developers.google.com/gmail/markup/reference/go-to-action
   def email_action(url)
@@ -49,4 +51,16 @@ module EmailsHelper
     msg = "This link is valid for #{password_reset_token_valid_time}.  "
     msg << "After it expires, you can #{link_tag}."
   end
+
+  def header_logo
+    if brand_item && brand_item.header_logo?
+      brand_header_logo
+    else
+      image_tag(
+        image_url('mailers/gitlab_header_logo.gif'),
+        size: "55x50",
+        alt: "GitLab"
+      )
+    end
+  end
 end

app/views/layouts/mailer.html.haml

@@ -48,7 +48,7 @@
           %td{ style: "font-family:'Helvetica Neue',Helvetica,Arial,sans-serif;background-color:#6b4fbb;height:4px;font-size:4px;line-height:4px;" }  
         %tr.header
           %td{ style: "font-family:'Helvetica Neue',Helvetica,Arial,sans-serif;padding:25px 0;font-size:13px;line-height:1.6;color:#5c5c5c;" }
-            %img{ alt: "GitLab", height: "50", src: image_url('mailers/gitlab_header_logo.gif'), width: "55" }/
+            = header_logo
         %tr
           %td{ style: "font-family:'Helvetica Neue',Helvetica,Arial,sans-serif;" }
             %table.wrapper{ border: "0", cellpadding: "0", cellspacing: "0", style: "width:640px;margin:0 auto;border-collapse:separate;border-spacing:0;" }

spec/helpers/emails_helper_spec.rb

@@ -43,4 +43,36 @@ describe EmailsHelper do
       end
     end
   end
+
+  describe '#header_logo' do
+    context 'there is a brand item with a logo' do
+      it 'returns the brand header logo' do
+        appearance = create :appearance, header_logo: fixture_file_upload(
+          Rails.root.join('spec/fixtures/dk.png')
+        )
+
+        expect(header_logo).to eq(
+          %{<img src="/uploads/appearance/header_logo/#{appearance.id}/dk.png" alt="Dk" />}
+        )
+      end
+    end
+
+    context 'there is a brand item without a logo' do
+      it 'returns the default header logo' do
+        create :appearance, header_logo: nil
+
+        expect(header_logo).to eq(
+          %{<img alt="GitLab" src="/images/mailers/gitlab_header_logo.gif" width="55" height="50" />}
+        )
+      end
+    end
+
+    context 'there is no brand item' do
+      it 'returns the default header logo' do
+        expect(header_logo).to eq(
+          %{<img alt="GitLab" src="/images/mailers/gitlab_header_logo.gif" width="55" height="50" />}
+        )
+      end
+    end
+  end
 end