Merge branch '367594-add-integration-logo-mattermost-slash-commands-notifications' into 'master'

Add integration logo: Mattermost notifications

See merge request !147893



Merged-by: Allen Cook <acook@gitlab.com>
Approved-by: Sam Word <sword@gitlab.com>
Approved-by: Allen Cook <acook@gitlab.com>
Co-authored-by: bmarjanovic <bmarjanovic@gitlab.com>

app/models/integrations/mattermost.rb

@@ -4,6 +4,7 @@ module Integrations
   class Mattermost < BaseChatNotification
     include SlackMattermostNotifier
     include SlackMattermostFields
+    include HasAvatar
 
     def self.title
       _('Mattermost notifications')

spec/models/integrations/mattermost_spec.rb

@@ -4,4 +4,5 @@
 
 RSpec.describe Integrations::Mattermost, feature_category: :integrations do
   it_behaves_like Integrations::SlackMattermostNotifier, "Mattermost"
+  it_behaves_like Integrations::HasAvatar
 end