Fix a nil error in Gitlab::Danger::Teammate

Signed-off-by: Rémy Coutable <remy@rymai.me>

lib/gitlab/danger/teammate.rb

@@ -39,9 +39,9 @@ module Gitlab
       def has_capability?(project, category, kind, labels)
         case category
         when :test
-          area = role[/Test Automation Engineer(?:.*?, (\w+))/, 1].downcase
+          area = role[/Test Automation Engineer(?:.*?, (\w+))/, 1]
 
-          area && labels.any?("devops::#{area}") if kind == :reviewer
+          area && labels.any?("devops::#{area.downcase}") if kind == :reviewer
         else
           capabilities(project).include?("#{kind} #{category}")
         end

spec/lib/gitlab/danger/teammate_spec.rb

@@ -50,6 +50,14 @@ describe Gitlab::Danger::Teammate do
         end
       end
 
+      context 'when role is Test Automation Engineer' do
+        let(:role) { 'Test Automation Engineer' }
+
+        it '#reviewer? returns false' do
+          expect(subject.reviewer?(project, :test, labels)).to be_falsey
+        end
+      end
+
       context 'when role is Test Automation Engineer, Manage' do
         let(:role) { 'Test Automation Engineer, Manage' }