Add .id method to PrometheusPanel class

app/models/performance_monitoring/prometheus_panel.rb

@@ -4,7 +4,7 @@ module PerformanceMonitoring
   class PrometheusPanel
     include ActiveModel::Model
 
-    attr_accessor :type, :title, :y_label, :weight, :metrics
+    attr_accessor :type, :title, :y_label, :weight, :metrics, :y_axis
 
     validates :title, presence: true
     validates :metrics, presence: true
@@ -20,5 +20,9 @@ module PerformanceMonitoring
 
       panel.tap(&:validate!)
     end
+
+    def id(group_title)
+      Digest::SHA2.hexdigest([group_title, type, title].join)
+    end
   end
 end

ee/spec/models/performance_monitoring/prometheus_panel_spec.rb

@@ -18,6 +18,16 @@ describe PerformanceMonitoring::PrometheusPanel do
     }
   end
 
+  describe '#new' do
+    it 'accepts old schema format' do
+      expect { described_class.new(json_content) }.not_to raise_error
+    end
+
+    it 'accepts new schema format' do
+      expect { described_class.new(json_content.merge("y_axis" => { "precision" => 0 })) }.not_to raise_error
+    end
+  end
+
   describe '.from_json' do
     subject { described_class.from_json(json_content) }
 
@@ -52,4 +62,15 @@ describe PerformanceMonitoring::PrometheusPanel do
       end
     end
   end
+
+  describe '.id' do
+    it 'returns hexdigest of group_title, type and title as the panel id' do
+      group_title = 'Business Group'
+      panel_type  = 'area-chart'
+      panel_title = 'New feature requests made'
+
+      expect(Digest::SHA2).to receive(:hexdigest).with("#{group_title}#{panel_type}#{panel_title}").and_return('hexdigest')
+      expect(described_class.new(title: panel_title, type: panel_type).id(group_title)).to eql 'hexdigest'
+    end
+  end
 end