Remove duplicated test from minitest

The test was implicitly testing if you can create duplicated issues. So
move *that* test to rspec

src/api/spec/models/attrib_spec.rb

@@ -150,6 +150,7 @@
 
       subject { build(:attrib, project: project, attrib_type: attrib_type, issues: [issue]) }
 
+      it { expect(subject).to be_invalid }
       it { expect(subject.errors.full_messages).to match_array(["Issues can't have issues"]) }
     end
 

src/api/spec/models/issue_spec.rb

@@ -42,5 +42,16 @@
     it 'CVE-XXXX-YYYY should be an invalid name' do
       expect { issue_cve.save! }.to raise_error(ActiveRecord::RecordInvalid, /does not match defined regex/)
     end
+
+    context 'with duplicated issues' do
+      let(:duplicated_issue) { build(:issue, name: '1234', issue_tracker: issue_tracker) }
+
+      it { expect(duplicated_issue).to be_invalid }
+
+      it 'has a proper error' do
+        duplicated_issue.save
+        expect(duplicated_issue.errors.full_messages).to match_array(['Name has already been taken'])
+      end
+    end
   end
 end

src/api/test/unit/attrib_test.rb

@@ -124,18 +124,6 @@ class AttribTest < ActiveSupport::TestCase
     assert_equal 'One', attrib.values.first.value
   end
 
-  test 'should have no issues' do
-    attrib_type = AttribType.new(attrib_namespace: @namespace, name: 'AttribIssues')
-    attrib = Attrib.new(attrib_type: attrib_type, project: Project.first)
-
-    bnc = IssueTracker.find_by_name('bnc')
-    attrib.issues << Issue.new(name: '12345', issue_tracker: bnc)
-    assert_not attrib.valid?
-    assert_equal ["can't have issues"], attrib.errors.messages[:issues]
-    attrib_type.issue_list = true
-    assert attrib.valid?, "attrib should be valid: #{attrib.errors.messages}"
-  end
-
   test 'find_by_container_and_fullname' do
     project = Project.find_by(name: 'BaseDistro2.0')
     attrib = Attrib.find_by_container_and_fullname(project, 'OBS:UpdateProject')