Add Save and Load Functions to SimService

test/service/simulation_service_test.dart

@@ -0,0 +1,23 @@
+import 'package:rules_of_living/service/engine_service.dart';
+import 'package:rules_of_living/service/simulation_service.dart';
+import 'package:rules_of_living/src/Simulation.dart';
+import 'package:test/test.dart';
+import 'package:mockito/mockito.dart';
+
+class MockSimulation extends Mock implements Simulation {}
+
+class MockEngineService extends Mock implements EngineService {}
+
+void main() {
+  SimulationService sut;
+  MockSimulation mockSim = MockSimulation();
+  setUp(() => sut = SimulationService(MockEngineService(), mockSim));
+  test("calling save calls through to Simulation.saveSnapshot", () {
+    sut.save();
+    verify(mockSim.saveSnapshot());
+  });
+  test("calling load calls through to Simulation.loadSnapshot", () {
+    sut.load();
+    verify(mockSim.loadSnapshot());
+  });
+}