干货 | Trip.com Flutter代码质量探索

int? aNullableInt = null; //可空声明
late int lateInt; //延迟声明
int value = a ?? b; //如果a为空则执行b
int value = aNullableInt!; //非空操作符
cat?.mouth.eat(); //如果为空不执行后面的方法
func(String a, {required String b, String? c}){} //必传参数和可空参数
List<String> //包含非空字符串的非空列表
List<String>? //包含非空字符串的可空列表
List<String?> //包含可空字符串的非空列表
List<String?>? //包含可空字符串的可空列表
var map = <String, int?>{'test': 1}; //未指定类型时{}是set类型
Function(String a)? func;
func("2"); // error
func?.call("2"); //ok

include: package:flutter_lints/flutter.yaml

#禁用隐式转换
analyzer:
  strong-mode:
    implicit-casts: false
    #implicit-dynamic: false 编译器无法确定类型的时候不会转换为dynamic

Map map = await HotelABTesting.getTestingInfo(); //error 不开启implicit-casts无任何提示
Map map = await HotelABTesting.getTestingInfo<Map>(); //warming  value of type 'Map<dynamic, dynamic>?' can't be assigned to a variable of type 'Map<dynamic, dynamic>'
Map? map = await HotelABTesting.getTestingInfo<Map>(); //ok
String data = map?["data"] //warming 不开启implicit-casts无警告
String data = map?["data"] ?? "" //开启implicit-casts 报警告 A value of type 'dynamic' can't be assigned to a variable of type 'String'
String data = (map？["data"] as String?) ?? ""; // ok

static Future<T?> getTestingInfo<T>() {
    return Bridge.callNativeStatic<T>("plugin-name", {});
}

analyzer:
  exclude:
    - build/**

errors:
    # 方法必须声明返回类型
    always_declare_return_types: warning
    # 不要给闭包的参数传null
    null_closures: warning
    dead_code: warning
    invalid_assignment: warning
    # 返回值缺失
    missing_return: warning
    # 无效的表达式
    unnecessary_statements: warning
    #未初始化的变量，尽量提供类型
    prefer_typing_uninitialized_variables: warning

linter:
  rules:
    - prefer_mixin
    # 尽量使用带有语义的参数代替true和false
    - avoid_positional_boolean_parameters
    - avoid_equals_and_hash_code_on_mutable_classes

main() {
  setUp(() {
    //初始化环境以及整个文件用到的数据
  });
  tearDown(() {
    //销毁数据
  });
  group("测试组描述", () {
    setUp(() {
      //初始化当前测试组用到的数据
    });
    tearDown(() {
      //销毁当前测试组用到的数据
    });
    test("单元测试描述", () {
      //构建测试对象
      //初始化测试数据
      //调用测试方法
      //校验结果
    });
  });
}

//通过该方法构建出父ViewModel，在每个用例用使用这个方法可以方便的获取到被测试的子ViewModel
Future<HotelSellingPointViewModel> initSellingPointViewModel(WidgetTester? tester, {
    pageIndex = 0, 
    subIndex = 0, 
    ...}) async {
    ...
    return viewModel;
 }

typedef MockFunction = Function(MethodCall methodCall);

MethodChannel _channel = MethodChannel('method_name', JSONMethodCodec());
Map<String, MockFunction> _mockMethod = {};
Map<String, dynamic> _network = {};

//根据服务名mock一个response
addMockNetwork(String? serviceName, response) {
  if (serviceName == null) { return; }
  _network[serviceName] = response;
}
//在用例中的setUp中调用，初始化mock环境
void hotelSetUp() {
  //该方法向_mockMethod中添加一个mock方法。
  addMockMethod("HTTPClient", "sendRequest", (methodCall) {
    var request = methodCall.arguments as Map;
    String url = request["url"];
    var res;
    _network.forEach((key, value) {
      if (url.contains("/${key.toString()}")) {
        res = value;
      }
    });
    return res;
  });
  _channel.setMockMethodCallHandler((MethodCall methodCall) async {
    if (_mockMethod.containsKey(methodCall.method)) {
      return _mockMethod[methodCall.method]!(methodCall);
    } else {
      print("插件${methodCall.method}没有被mock");
    }
  });
}

 * Testing with real objects is preferred over testing with mocks
  * Don‘t mock a type you don’t own!  Don‘t mock value objects!
  * Don't mock everything, it's an anti-pattern
  * Because instantiating the object is too painful !? => not a valid reason.

```
//dart run build_runner build 生成Mock实例类
@GenerateMocks([Cat])
void main() {
  // Create mock object.
  var cat = MockCat();
}
when(cat.sound()).thenReturn("Purr");
expect(cat.sound(), "Purr");
verify(cat.sound());//verifyInOrder, or verifyNever
//参数匹配
when(cat.eatFood(argThat(startsWith("dry")))).thenReturn(false);
verify(cat.eatFood(argThat(contains("food"))));
//参数校验
expect(verify(cat.eatFood(captureAny)).captured, ["Milk", "Fish"]);
expect(verify(cat.eatFood(captureThat(startsWith("F")))).captured, ["Fish"]);
verify(cat.eatFood("Fish")).called(1);
// Waiting for a call.
cat.eatFood("Fish");
await untilCalled(cat.chew()); // Completes when cat.chew() is called.
```

void expect(
  dynamic actual,
  dynamic matcher, {
  String? reason,
  dynamic skip, // true or a String
})

expect(string.trim(), equals('result')); \\ equals('result')可以使用result代替
expect('foo,bar,baz', allOf([
      contains('foo'),
      isNot(startsWith('bar')),
      endsWith('baz')
    ]));
expect(Future.value(10), completion(equals(10)));
expect(find.text("确认"), findsOneWidget);

//使用方式
expect(verifyNetWork(serviceName).last["body"]["isAllowDuplicate"], "T", reason: "isAllowDuplicate应该为T");
expect(verifyUBT(traceKey), isNotEmpty);

//通过插件名来获取一个插件最近调用, 返回值为改插件调用MethodCall的列表，可以通过last方法获取最近一次接口调用的参数
List<MethodCall> verifyMethod(String plugin, String methodName) {
  return _methodCallRecord.where((element) => element.method == "$plugin-$methodName").toList();
}

//通过serviceName来获取最近该接口的调用参数。
List<Map<String,dynamic>> verifyNetWork(String? serviceName) { ... }

//通过埋点key获取埋点的参数
List<Map<String, dynamic>> verifyUBT(String key) { ... }

 List<MethodCall> _methodCallRecord = [];

//在MockHandler方法中，可以记录每个插件调用的methodCall
_channel.setMockMethodCallHandler((MethodCall methodCall) async {
  _methodCallRecord.add(methodCall);
});

//使用方式
HotelBookExpectHelper.expectReservationRequest(verifyNetWork(HotelService.reservation.serviceName).last, checkIn: "2021-09-09");

static expectReservationRequest(Map request, {String? checkIn ...}) {
  Map<String, dynamic>? body = request["body"];
  if (body == null) {
    throw TestFailure("创单请求body为空");
  }
  if (checkIn != null) {
    expect(body["dateRange"]?["checkIn"], checkIn, reason: "创单入住时间不对");
  }
  ...
}

testWidgets("dialog", (WidgetTester tester) async {
  BuildContext context =
      await HotelDialogTestHelper.listenDialogShow(tester, callback: (DialogRoute<dynamic> route, Widget dialog) {});
  HotelDialog(content: "context", positiveText: "confirm").show(context);
  await tester.pumpAndSettle();
  expect(find.text("context"), findsOneWidget);
});

static Future<BuildContext> listenDialogShow(WidgetTester tester,
    {GlobalKey? globalKey, required DialogTestCallback callback}) async {
  await tester.pumpWidget(Builder(builder: (context) {
    return MaterialApp(routes: {
      "/": (context) => Text("1", key: globalKey),
    }, navigatorObservers: [
      MyObserver(context, callback)
    ]);
  }));
  return find.text("1").evaluate().first;
}

testWidgets('BookPage-reservation', (widgetTester) async {
    await HotelBookOperation.pumpBookPage(widgetTester);
    await HotelBookGuestOperation.addGuest(widgetTester, "张", "三");
    await HotelBookContactOperation.addContact(widgetTester, "1@qq.com", "13777488293");
    await HotelBottomBarOperation.tapBook(widgetTester);
    await HotelBookContactOperation.submitMailConfirm(widgetTester);
    HotelBookExpectHelper.expectReservationRequest(verifyNetWork(HotelService.reservation.serviceName).last,
        checkIn: "2021-09-09",
        checkOut: "2021-09-10",
        roomCount: 1,
        fromDateTime: "2021-09-09 17:00:00",
        toDateTime: "2021-09-10 06:00:00",
        isAllowDuplicateResv: "F",
        guestNames: [
          {"familyName": "三", "givenName": "张", "roomIndex": 1}
        ],
        contactEmail: "1@qq.com",
        contactPhoneNumber: "13777488293");
  });

static Future addGuest(WidgetTester widgetTester, String surName, String givenName) async {
  try {
    List<HotelBookTextField> testField =
        widgetTester.widgetList<HotelBookTextField>(find.byType(HotelBookTextField)).toList();
    widgetTester.widgetList<SharkText>(find.byType(SharkText)).toList();
    testField[0].editingController?.value = TextEditingValue(
        text: surName, selection: TextSelection(baseOffset: surName.length, extentOffset: surName.length));
    testField[1].editingController?.value = TextEditingValue(
        text: givenName, selection: TextSelection(baseOffset: givenName.length, extentOffset: givenName.length));
    await widgetTester.pump();
  } catch (e) {
    throw TestFailure("添加入住人失败" + e.toString());
  }
}

先安装lcov
brew install lcov
flutter test --coverage
lcov --extract coverage/lcov.info lib/*/*view_model.dart' -o coverage/extract.info
genhtml coverage/extract.info -o coverage/html
open coverage/html/index.html