Add last overall update to Dashboard

lib/dashboard_stats.rb

@@ -17,6 +17,10 @@ def total_organisations
     api_catalogue.organisations_apis.count
   end
 
+  def last_updated
+    by_organisation.max_by(&:last_updated)&.last_updated
+  end
+
   def by_organisation
     @_by_organsation ||= calculate_stats_by_organisation
   end

source/dashboard.html.erb

@@ -11,13 +11,15 @@ hide_in_navigation: true
     <tr>
       <th>Total APIs:</th>
       <th>Departments Represented:</th>
+      <th>Last Update:</th>
     </tr>
   </thead>
 
   <tbody>
     <tr>
       <td><%= dashboard_stats.total_apis %></td>
       <td><%= dashboard_stats.total_organisations %></td>
+      <td><%= dashboard_stats.last_updated %></td>
     </tr>
   </tbody>
 </table>

spec/lib/dashboard_stats_spec.rb

@@ -20,6 +20,23 @@
     end
   end
 
+  describe "#last_updated" do
+    let(:apis) do
+      [
+        instance_double(Api, organisation: "A", name: "A1", date_updated: Date.new(2020, 1, 1), date_added: Date.new(2016, 1, 1), provider: nil),
+        instance_double(Api, organisation: "A", name: "A2", date_updated: Date.new(2019, 1, 1), date_added: Date.new(2016, 1, 1), provider: nil),
+        instance_double(Api, organisation: "B", name: "B1", date_updated: Date.new(2018, 1, 1), date_added: Date.new(2016, 1, 1), provider: nil),
+        instance_double(Api, organisation: "C", name: "C1", date_updated: Date.new(2017, 1, 1), date_added: Date.new(2016, 1, 1), provider: nil),
+      ]
+    end
+
+    let(:api_catalogue) { ApiCatalogue.new(apis) }
+
+    it "matches the most recently updated API" do
+      expect(subject.last_updated).to eq Date.new(2020, 1, 1)
+    end
+  end
+
   describe "#by_organisation" do
     it "provides stats per organisation" do
       nhs_stats = subject.by_organisation.detect do |stats|