Extract EngineService into separate service

lib/app_component.dart

@@ -5,6 +5,7 @@ import 'package:rules_of_living/components/controls_component.dart';
 import 'package:rules_of_living/components/header_component.dart';
 import 'package:rules_of_living/components/simulation_component.dart';
 import 'package:rules_of_living/service/configuration_service.dart';
+import 'package:rules_of_living/service/control_service.dart';
 import 'package:rules_of_living/service/engine_service.dart';
 
 @Component(
@@ -20,8 +21,16 @@ import 'package:rules_of_living/service/engine_service.dart';
     ControlsComponent,
     ConfigurationComponent
   ],
-  providers: [materialProviders, ClassProvider(EngineService), ClassProvider(ConfigurationService)],
-  styleUrls: const ['package:angular_components/app_layout/layout.scss.css', 'app_component.css'],
+  providers: [
+    materialProviders,
+    ClassProvider(EngineService),
+    ClassProvider(ConfigurationService),
+    ClassProvider(EngineService)
+  ],
+  styleUrls: const [
+    'package:angular_components/app_layout/layout.scss.css',
+    'app_component.css'
+  ],
 )
 class AppComponent {
   var name = "World";

lib/components/controls_component.dart

@@ -1,6 +1,6 @@
 import 'package:angular/angular.dart';
 import 'package:angular_components/angular_components.dart';
-import 'package:rules_of_living/service/engine_service.dart';
+import 'package:rules_of_living/service/control_service.dart';
 
 @Component(
   selector: 'sim-controls',
@@ -15,27 +15,27 @@ import 'package:rules_of_living/service/engine_service.dart';
   styleUrls: const ["controls_component.css"],
 )
 class ControlsComponent {
-  final EngineService engine;
+  final ControlService ctrl;
 
-  ControlsComponent(this.engine);
+  ControlsComponent(this.ctrl);
 
   void onStartClicked() {
-    engine.toggleRunning();
+    ctrl.toggleRunning();
   }
 
   void onStepClicked() {
-    engine.step();
+    ctrl.step();
   }
 
   void onResetClicked() {
-    engine.reset();
+    ctrl.reset();
   }
 
   void onRandomClicked() {
-    engine.addRandomPattern();
+    ctrl.addRandomPattern();
   }
 
   void onClearClicked() {
-    engine.clear();
+    ctrl.clear();
   }
 }

lib/components/simulation_component.dart

@@ -1,7 +1,7 @@
 import 'dart:html' as html;
 
 import 'package:angular/angular.dart';
-import 'package:rules_of_living/service/engine_service.dart';
+import 'package:rules_of_living/service/control_service.dart';
 
 @Component(
   selector: 'gol-simulation',
@@ -10,9 +10,9 @@ import 'package:rules_of_living/service/engine_service.dart';
   providers: [],
 )
 class SimulationComponent implements OnInit {
-  final EngineService engineService;
+  final ControlService ctrl;
 
-  SimulationComponent(this.engineService);
+  SimulationComponent(this.ctrl);
 
   @override
   void ngOnInit() {
@@ -29,6 +29,6 @@ class SimulationComponent implements OnInit {
     
     the canvas did not load correctly :(
     ''', canvas.width / 2 - 50, canvas.height / 2);
-    engineService.canvas = canvas;
+    ctrl.canvas = canvas;
   }
 }

lib/service/configuration_service.dart

@@ -3,7 +3,7 @@ import 'dart:math';
 import 'package:rules_of_living/service/engine_service.dart';
 
 class ConfigurationService {
-  final EngineService engineService;
+  final EngineService _es;
 
   bool showGrid;
 
@@ -17,10 +17,10 @@ class ConfigurationService {
   int get simSpeed => _simSpeed;
   void set simSpeed(int val) {
     _simSpeed = val;
-    engineService.engine.stepsPerSecond = simSpeed;
+    _es.engine.stepsPerSecond = simSpeed;
   }
 
-  ConfigurationService(this.engineService) {
+  ConfigurationService(this._es) {
     showGrid = false;
     simSpeed = 5;
   }
@@ -30,8 +30,8 @@ class ConfigurationService {
   }
 
   void setGridSize({int x, int y}) {
-    x = x ?? engineService.engine.gridSize.x;
-    y = y ?? engineService.engine.gridSize.y;
-    engineService.engine.gridSize = Point(x, y);
+    x = x ?? _es.engine.gridSize.x;
+    y = y ?? _es.engine.gridSize.y;
+    _es.engine.gridSize = Point(x, y);
   }
 }

lib/service/control_service.dart

@@ -0,0 +1,43 @@
+import 'dart:html' as html;
+
+import 'package:rules_of_living/service/engine_service.dart';
+
+class ControlService {
+  EngineService _es;
+
+  ControlService(this._es);
+
+  void set canvas(html.CanvasElement canvas) => _es.engine.canvas = canvas;
+  html.CanvasElement get canvas => _es.engine.canvas;
+
+  void run() {
+    _es.engine.running = true;
+  }
+
+  void stop() {
+    _es.engine.running = false;
+  }
+
+  void toggleRunning() {
+    _es.engine.running = !_es.engine.running;
+  }
+
+  void step() {
+    _es.engine.step();
+  }
+
+  void reset() {
+    _es.engine.reset();
+  }
+
+  void addRandomPattern() {
+    _es.engine.running = false;
+    _es.engine.addPattern();
+  }
+
+  void clear() {
+    _es.engine.clear();
+  }
+
+  bool get isRunning => _es.engine.running;
+}

lib/service/engine_service.dart

@@ -1,48 +1,15 @@
-import 'dart:html' as html;
-
 import 'package:rules_of_living/src/Engine.dart';
 
 class EngineService {
-  Engine _engine;
+  Engine _uncachedEngineAccess;
 
-  Engine get engine => _engine ?? getEngine(Engine());
-
-  Engine getEngine(Engine engine) {
-    _engine = engine;
-    return _engine;
+  Engine get engine => _uncachedEngineAccess ?? _setCachedAndReturn(Engine());
+  void set engine(Engine newEngine) {
+    _uncachedEngineAccess = newEngine;
   }
 
-  void set canvas(html.CanvasElement canvas) => engine.canvas = canvas;
-  html.CanvasElement get canvas => engine.canvas;
-
-  void run() {
-    engine.running = true;
+  Engine _setCachedAndReturn(Engine newEngine) {
+    engine = newEngine;
+    return newEngine;
   }
-
-  void stop() {
-    engine.running = false;
-  }
-
-  void toggleRunning() {
-    engine.running = !engine.running;
-  }
-
-  void step() {
-    engine.step();
-  }
-
-  void reset() {
-    engine.reset();
-  }
-
-  void addRandomPattern() {
-    engine.running = false;
-    engine.addPattern();
-  }
-
-  void clear() {
-    engine.clear();
-  }
-
-  bool get isRunning => engine.running;
 }

test/service/configuration_service_test.dart

@@ -1,11 +1,11 @@
 import 'dart:math';
 
+import 'package:mockito/mockito.dart';
+import 'package:rules_of_living/service/configuration_service.dart';
+import 'package:rules_of_living/service/engine_service.dart';
 import 'package:rules_of_living/src/Engine.dart';
 @TestOn('browser')
 import 'package:test/test.dart';
-import 'package:rules_of_living/service/configuration_service.dart';
-import 'package:rules_of_living/service/engine_service.dart';
-import 'package:mockito/mockito.dart';
 
 class MockEngine extends Mock implements Engine {}
 
@@ -16,7 +16,7 @@ void main() {
   setUp(() {
     me = MockEngine();
     engineService = EngineService();
-    engineService.getEngine(me);
+    engineService.engine = me;
     sut = ConfigurationService(engineService);
   });
 

test/service/engine_service_test.dart

@@ -14,8 +14,8 @@ void main() {
     sut = EngineService();
   });
   group("Dependency Injection", () {
-    test("EngineService accesses the Engine defined in getEngine", () {
-      sut.getEngine(me);
+    test("EngineService can be passed a custom Engine", () {
+      sut.engine = me;
 
       Engine result = sut.engine;
       expect(result, equals(me));
@@ -33,7 +33,7 @@ void main() {
     });
     test("caching can be overriden by providing a custom engine", () {
       Engine first = sut.engine;
-      sut.getEngine(me);
+      sut.engine = me;
       Engine second = sut.engine;
       expect(second, isNot(equals(first)));
     });