Refactor: model errors for multi cluster validation

The current approach requires catching exceptions to handle these errors
and callers are already handling model validations so it seems more
appropriate.  Also it seemed to convoluted to add this logic directly to
the model since the model needs to check too many possible associations
to determine whether or not there are more than one cluster since the
model doesn't know what it's being created on. Additionally we only
wanted to validate during create to avoid the risk of existing models
becoming invalid by many different edge cases.

1 files changed, 13 insertions, 3 deletions

diff --git a/spec/requests/api/project_clusters_spec.rb b/spec/requests/api/project_clusters_spec.rb
index a6e08ab3ab6..e8ed016db69 100644
--- a/spec/requests/api/project_clusters_spec.rb
+++ b/spec/requests/api/project_clusters_spec.rb
@@ -257,12 +257,22 @@ describe API::ProjectClusters do
         post api("/projects/#{project.id}/clusters/user", current_user), params: cluster_params
       end
 
+      it 'responds with 400' do
+        expect(response).to have_gitlab_http_status(400)
+
+        expect(json_response['message']['base'].first).to eq('Instance does not support multiple Kubernetes clusters')
+      end
+    end
+
+    context 'non-authorized user' do
+      before do
+        post api("/projects/#{project.id}/clusters/user", developer_user), params: cluster_params
+      end
+
       it 'responds with 403' do
         expect(response).to have_gitlab_http_status(403)
-      end
 
-      it 'returns an appropriate message' do
-        expect(json_response['message']).to include('Instance does not support multiple Kubernetes clusters')
+        expect(json_response['message']).to eq('403 Forbidden')
       end
     end
   end