Ensure audit event is added when user is destroyed

Integration test is also added to extend coverage for both soft
delete (delete user, not contributions) and hard delete (delete
user only).

ee/app/services/ee/users/destroy_service.rb

@@ -7,11 +7,11 @@ module EE
 
       override :execute
       def execute(user, options = {})
-        super(user, options) do |delete_user|
+        result = super(user, options) do |delete_user|
           mirror_cleanup(delete_user)
         end
 
-        log_audit_event(user) if options[:hard_delete]
+        log_audit_event(user) if result.destroyed?
       end
 
       def mirror_cleanup(user)

ee/spec/services/users/destroy_service_spec.rb

@@ -15,17 +15,58 @@ describe Users::DestroyService do
         stub_licensed_features(admin_audit_log: true)
       end
 
-      context 'when hard_delete' do
-        let(:hard_delete) { true }
+      context 'soft delete' do
+        let(:hard_delete) { false }
+
+        context 'when user destroy operation succeeds' do
+          it 'logs audit events for ghost user migration and destroy operation' do
+            service.execute(user, hard_delete: hard_delete)
+
+            expect(AuditEvent.last(3)).to contain_exactly(
+              have_attributes(details: hash_including(change: 'email address')),
+              have_attributes(details: hash_including(change: 'username')),
+              have_attributes(details: hash_including(remove: 'user'))
+            )
+          end
+        end
 
-        it 'logs audit event' do
-          expected_message = "Removed user"
+        context 'when user destroy operation fails' do
+          before do
+            allow(user).to receive(:destroy).and_return(user)
+          end
 
-          expect do
+          it 'logs audit events for ghost user migration operation' do
             service.execute(user, hard_delete: hard_delete)
-          end.to change { AuditEvent.count }.by(1)
 
-          expect(AuditEvent.last.present.action).to eq(expected_message)
+            expect(AuditEvent.last(2)).to contain_exactly(
+              have_attributes(details: hash_including(change: 'email address')),
+              have_attributes(details: hash_including(change: 'username'))
+            )
+          end
+        end
+      end
+
+      context 'hard delete' do
+        let(:hard_delete) { true }
+
+        context 'when user destroy operation succeeds' do
+          it 'logs audit events for destroy operation' do
+            service.execute(user, hard_delete: hard_delete)
+
+            expect(AuditEvent.last)
+              .to have_attributes(details: hash_including(remove: 'user'))
+          end
+        end
+
+        context 'when user destroy operation fails' do
+          before do
+            allow(user).to receive(:destroy).and_return(user)
+          end
+
+          it 'does not log any audit event' do
+            expect { service.execute(user, hard_delete: hard_delete) }
+              .not_to change { AuditEvent.count }
+          end
         end
       end
     end