Add ems_events for ems_event_filter_column for ems cluster subclasses

EmsCluster was properly having ems_cluster_id as the ems_event_filter_column,
subclasses had cluster_id as the column.

Implementing a basic events <-> cluster lookup via foreign_key.  If desired
we can add something like event_where_clause has for showing hosts and vms events
in the cluster.  For now, that's too much performance overhead so we're looking
at just cluster events in the timeline.

app/models/ems_cluster.rb

@@ -182,6 +182,11 @@ def parent_datacenter
     detect_ancestor(:of_type => 'EmsFolder') { |a| a.kind_of?(Datacenter) }
   end
 
+  # TODO: event_where_clause tacks on additional possibly expensive queries
+  # such as all events for all hosts or vms in the cluster.
+  # For now, we're looking at ems events specifically for the ems cluster.
+  has_many :ems_events, :foreign_key => :ems_cluster_id, :class_name => "EmsEvent"
+
   def event_where_clause(assoc = :ems_events)
     return ["ems_cluster_id = ?", id] if assoc.to_sym == :policy_events
 

spec/models/mixins/event_mixin_spec.rb

@@ -58,20 +58,26 @@ def event_where_clause(assoc)
       VmOrTemplate        vm_or_template_id
       Vm                  vm_or_template_id
     ].each_slice(2) do |klass, column|
-      it "#{klass} uses #{column} and target_id and target_type" do
-        obj = FactoryBot.create(klass.tableize.singularize)
-        expect(obj.event_stream_filters["EmsEvent"]).to eq(column => obj.id)
-        expect(obj.event_stream_filters.dig("MiqEvent", "target_id")).to eq(obj.id)
-        expect(obj.event_stream_filters.dig("MiqEvent", "target_type")).to eq(obj.class.base_class.name)
-      end
-
-      it "#{klass} behaves like event_where_clause for ems_events" do
-        obj = FactoryBot.create(klass.tableize.singularize)
-        event = FactoryBot.create(:event_stream, column => obj.id)
-        FactoryBot.create(:event_stream)
-        expect(EventStream.where(obj.event_stream_filters["EmsEvent"]).to_a).to eq([event])
-        expect(EventStream.where(obj.event_where_clause(:ems_events)).to_a).to eq([event])
+      klasses = klass.constantize.descendants.collect(&:name).unshift(klass)
+      klasses.each do |klass|
+        it "#{klass} uses #{column} and target_id and target_type" do
+          begin
+            obj = FactoryBot.build(klass.tableize.singularize, :name => "test")
+          rescue NameError
+            skip "Unable to build factory from name: #{klass}, possibly due to inflections"
+          end
+          expect(obj.event_stream_filters["EmsEvent"]).to eq(column => obj.id)
+          expect(obj.event_stream_filters.dig("MiqEvent", "target_id")).to eq(obj.id)
+          expect(obj.event_stream_filters.dig("MiqEvent", "target_type")).to eq(obj.class.base_class.name)
+        end
       end
+    it "#{klass} behaves like event_where_clause for ems_events" do
+      obj = FactoryBot.create(klass.tableize.singularize)
+      event = FactoryBot.create(:event_stream, column => obj.id)
+      FactoryBot.create(:event_stream)
+      expect(EventStream.where(obj.event_stream_filters["EmsEvent"]).to_a).to eq([event])
+      expect(EventStream.where(obj.event_where_clause(:ems_events)).to_a).to eq([event])
+    end
 
       # # TODO: some classes don't have this implemented or don't have columns for this
       # # Do we consolidate policy events and miq events?