Raise insertion errors from BigQuery

When inserting data in to BigQuery we need to inspect the response for
errors as although it may have a 200 HTTP status code, schema-related
errors that occur on insertion are included in the error information of
the response.

See
https://cloud.google.com/bigquery/docs/error-messages#streaming-success
for more information on this.

lib/dfe/analytics/send_events.rb

@@ -15,9 +15,25 @@ def perform(events)
         if DfE::Analytics.log_only?
           Rails.logger.info("DfE::Analytics: #{events.inspect}")
         else
-          DfE::Analytics.events_client.insert(events, ignore_unknown: true)
+          response = DfE::Analytics.events_client.insert(events, ignore_unknown: true)
+          raise SendEventsError, response.insert_errors unless response.success?
         end
       end
     end
+
+    class SendEventsError < StandardError
+      attr_reader :insert_errors
+
+      def initialize(insert_errors)
+        @insert_errors = insert_errors
+
+        message = insert_errors
+          .flat_map(&:errors)
+          .map { |error| error['message'] }
+          .compact.join("\n")
+
+        super("Could not insert all events:\n#{message}")
+      end
+    end
   end
 end

lib/dfe/analytics/testing.rb

@@ -40,8 +40,10 @@ def switch_test_mode(test_mode)
     end
 
     class StubClient
+      Response = Struct.new(:success?)
+
       def insert(*)
-        true
+        Response.new(true)
       end
     end
 

lib/dfe/analytics/testing/helpers.rb

@@ -37,6 +37,27 @@ def stub_analytics_event_submission
             .to_return(status: 200, body: '{}', headers: { 'Content-Type' => 'application/json' })
         end
 
+        def stub_analytics_event_submission_with_insert_errors
+          stub_bigquery_auth!
+
+          body = {
+            insertErrors: [
+              {
+                index: 0,
+                errors: [
+                  {
+                    reason: 'error',
+                    message: 'An error.'
+                  }
+                ]
+              }
+            ]
+          }
+
+          stub_request(:post, /bigquery.googleapis.com/)
+            .to_return(status: 200, body: body.to_json, headers: { 'Content-Type' => 'application/json' })
+        end
+
         def with_analytics_config(options)
           old_config = DfE::Analytics.config.dup
           DfE::Analytics.configure do |config|

spec/dfe/analytics/send_events_spec.rb

@@ -30,6 +30,26 @@
       end
     end
 
+    context 'when the request is not successful' do
+      before { stub_analytics_event_submission_with_insert_errors }
+
+      subject(:perform) do
+        DfE::Analytics::Testing.webmock! do
+          described_class.new.perform([event.as_json])
+        end
+      end
+
+      it 'raises an exception' do
+        expect { perform }.to raise_error(DfE::Analytics::SendEventsError, /An error./)
+      end
+
+      it 'contains the insert errors' do
+        perform
+      rescue DfE::Analytics::SendEventsError => e
+        expect(e.insert_errors).to_not be_empty
+      end
+    end
+
     context 'when "log_only" is set' do
       before do
         allow(DfE::Analytics).to receive(:log_only?).and_return true