Update specs to improve coverage

ee/spec/models/project_spec.rb

@@ -1729,6 +1729,7 @@ RSpec.describe Project do
 
     subject { project.disabled_integrations }
 
+    context 'github' do
       where(:license_feature, :disabled_integrations) do
         :github_project_service_integration | %w[github]
       end
@@ -1752,6 +1753,27 @@ RSpec.describe Project do
       end
     end
 
+    context 'slack' do
+      let(:slack_app_enabled) { false }
+
+      where(:development, :slack_app_enabled, :disabled_integrations) do
+        true | true | []
+        true | false | []
+        false | true | %w[slack_slash_commands]
+        false | false | %w[gitlab_slack_application]
+      end
+
+      with_them do
+        before do
+          allow(Rails.env).to receive(:development?).and_return(development)
+          allow(Gitlab::CurrentSettings).to receive(:slack_app_enabled).and_return(slack_app_enabled)
+        end
+
+        it { is_expected.to include(*disabled_integrations) }
+      end
+    end
+  end
+
   describe '#pull_mirror_available?' do
     let(:project) { create(:project) }