Associate clusters model to groups34758-create-group-clusters

Even though we currently only should have one group for a cluster, we
allow the flexibility to associate to other groups in the future.

This also matches the runner <=> groups association.

- Adds Cluster#first_group, aliased to Cluster#group. For the
conceivable future, a cluster will have at most one group.

- Prevent mixing of group and project clusters. If project type
clusters, it should only have projects assigned.  Similarly with groups.

- Default cluster_type to :project_type. As it's very small table we can
set default and null: false in one release.

1 files changed, 15 insertions, 0 deletions

diff --git a/spec/factories/clusters/clusters.rb b/spec/factories/clusters/clusters.rb
index bbeba8ce8b9..c9f5d0a813e 100644
--- a/spec/factories/clusters/clusters.rb
+++ b/spec/factories/clusters/clusters.rb
@@ -2,13 +2,28 @@ FactoryBot.define do
   factory :cluster, class: Clusters::Cluster do
     user
     name 'test-cluster'
+    cluster_type :project_type
+
+    trait :instance do
+      cluster_type { Clusters::Cluster.cluster_types[:instance_type] }
+    end
 
     trait :project do
+      cluster_type { Clusters::Cluster.cluster_types[:project_type] }
+
       before(:create) do |cluster, evaluator|
         cluster.projects << create(:project, :repository)
       end
     end
 
+    trait :group do
+      cluster_type { Clusters::Cluster.cluster_types[:group_type] }
+
+      before(:create) do |cluster, evalutor|
+        cluster.groups << create(:group)
+      end
+    end
+
     trait :provided_by_user do
       provider_type :user
       platform_type :kubernetes