fix test

lib/core/error/exceptions.dart

@@ -1,3 +1,27 @@
+import 'package:dartz/dartz.dart';
+
+import 'failures.dart';
+
 class ServerException implements Exception {}
 
 class CacheException implements Exception {}
+
+typedef Future<Either<Failure, T>> _function<T>();
+
+Future<Either<Failure, T>> catchServerException<T>(
+    _function<T> functionBody) async {
+  try {
+    return await functionBody();
+  } on ServerException {
+    return Left(ServerFailure());
+  }
+}
+
+Future<Either<Failure, T>> catchCacheException<T>(
+    _function<T> functionBody) async {
+  try {
+    return await functionBody();
+  } on CacheException {
+    return Left(CacheFailure());
+  }
+}

lib/core/usecases/usecase.dart

@@ -7,6 +7,8 @@ abstract class UseCase<Type, Params> {
   Future<Either<Failure, Type>> call(Params params);
 }
 
+// This will be used by the code calling the use case whenever the use case
+// doesn't accept any parameters.
 class NoParams extends Equatable {
   @override
   List<Object> get props => [];

lib/core/util/input_converter.dart

@@ -5,8 +5,12 @@ class InputConverter {
   Either<Failure, int> stringToUnsignedInteger(String str) {
     try {
       final integer = int.parse(str);
-      if (integer < 0) throw FormatException();
+      if (integer < 0) {
+        throw FormatException();
+      }
       return Right(integer);
+    } on ArgumentError {
+      return Left(InvalidInputFailure());
     } on FormatException {
       return Left(InvalidInputFailure());
     }

lib/features/number_trivia/data/datasources/number_trivia_local_data_source.dart

@@ -28,9 +28,8 @@ class NumberTriviaLocalDataSourceImpl implements NumberTriviaLocalDataSource {
     final jsonString = sharedPreferences.getString(CACHED_NUMBER_TRIVIA);
     if (jsonString != null) {
       return Future.value(NumberTriviaModel.fromJson(json.decode(jsonString)));
-    } else {
-      throw CacheException();
     }
+    throw CacheException();
   }
 
   @override

lib/features/number_trivia/data/datasources/number_trivia_remote_data_source.dart

@@ -32,17 +32,20 @@ class NumberTriviaRemoteDataSourceImpl implements NumberTriviaRemoteDataSource {
       _getTriviaFromUrl('http://numbersapi.com/random');
 
   Future<NumberTriviaModel> _getTriviaFromUrl(String url) async {
-    final response = await client.get(
-      url,
-      headers: {
-        'Content-Type': 'application/json',
-      },
-    );
-
-    if (response.statusCode == 200) {
-      return NumberTriviaModel.fromJson(json.decode(response.body));
-    } else {
-      throw ServerException();
+    try {
+      final response = await client.get(
+        url,
+        headers: {
+          'Content-Type': 'application/json',
+        },
+      );
+
+      if (response.statusCode == 200) {
+        return NumberTriviaModel.fromJson(json.decode(response.body));
+      }
+    } catch (e) {
+      print(e);
     }
+    throw ServerException();
   }
 }

lib/features/number_trivia/data/repositories/number_trivia_repository_impl.dart

@@ -9,7 +9,7 @@ import '../../domain/repositories/number_trivia_repository.dart';
 import '../datasources/number_trivia_local_data_source.dart';
 import '../datasources/number_trivia_remote_data_source.dart';
 
-typedef Future<NumberTrivia> _ConcreteOrRandomChooser();
+typedef Future<Either<Failure, T>> _ConcreteOrRandomChooser<T>();
 
 class NumberTriviaRepositoryImpl implements NumberTriviaRepository {
   final NumberTriviaRemoteDataSource remoteDataSource;
@@ -26,36 +26,37 @@ class NumberTriviaRepositoryImpl implements NumberTriviaRepository {
   Future<Either<Failure, NumberTrivia>> getConcreteNumberTrivia(
     int number,
   ) async {
-    return await _getTrivia(() {
-      return remoteDataSource.getConcreteNumberTrivia(number);
+    return await _handleException(() {
+      return saveToLocalCache(() => remoteDataSource.getConcreteNumberTrivia(number));
     });
   }
 
   @override
   Future<Either<Failure, NumberTrivia>> getRandomNumberTrivia() async {
-    return await _getTrivia(() {
-      return remoteDataSource.getRandomNumberTrivia();
+    return await _handleException(() {
+      return saveToLocalCache(remoteDataSource.getRandomNumberTrivia);
     });
   }
 
-  Future<Either<Failure, NumberTrivia>> _getTrivia(
+  Future<Either<Failure, NumberTrivia>> _handleException(
     _ConcreteOrRandomChooser getConcreteOrRandom,
   ) async {
     if (await networkInfo.isConnected) {
-      try {
-        final remoteTrivia = await getConcreteOrRandom();
-        localDataSource.cacheNumberTrivia(remoteTrivia);
-        return Right(remoteTrivia);
-      } on ServerException {
-        return Left(ServerFailure());
-      }
-    } else {
-      try {
-        final localTrivia = await localDataSource.getLastNumberTrivia();
-        return Right(localTrivia);
-      } on CacheException {
-        return Left(CacheFailure());
-      }
+      return catchServerException(getConcreteOrRandom);
     }
+    return catchCacheException(_getLastNumberTriviaInCache);
+  }
+
+  Future<Either<Failure, NumberTrivia>> saveToLocalCache(
+    getConcreteOrRandom,
+  ) async {
+    final remoteTrivia = await getConcreteOrRandom();
+    localDataSource.cacheNumberTrivia(remoteTrivia);
+    return Right(remoteTrivia);
+  }
+
+  Future<Either<Failure, NumberTrivia>> _getLastNumberTriviaInCache() async {
+    final localTrivia = await localDataSource.getLastNumberTrivia();
+    return Right(localTrivia);
   }
 }

lib/features/number_trivia/presentation/bloc/number_trivia_bloc.dart

@@ -1,6 +1,6 @@
 import 'dart:async';
 
-import 'package:bloc/bloc.dart';
+import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:clean_architecture_tdd_course/core/error/failures.dart';
 import 'package:clean_architecture_tdd_course/core/usecases/usecase.dart';
 import 'package:clean_architecture_tdd_course/features/number_trivia/domain/entities/number_trivia.dart';
@@ -39,6 +39,8 @@ class NumberTriviaBloc extends Bloc<NumberTriviaEvent, NumberTriviaState> {
   Stream<NumberTriviaState> mapEventToState(
     NumberTriviaEvent event,
   ) async* {
+    // Immediately branching the logic with type checking, in order
+    // for the event to be smart casted
     if (event is GetTriviaForConcreteNumber) {
       final inputEither =
           inputConverter.stringToUnsignedInteger(event.numberString);

test/core/util/input_converter_test.dart

@@ -22,6 +22,18 @@ void main() {
       },
     );
 
+    test(
+      'should return a Failure when the string is null',
+      () async {
+        // arrange
+        final str = null;
+        // act
+        final result = inputConverter.stringToUnsignedInteger(str);
+        // assert
+        expect(result, Left(InvalidInputFailure()));
+      },
+    );
+
     test(
       'should return a Failure when the string is not an integer',
       () async {

test/features/number_trivia/data/datasources/number_trivia_local_data_source_test.dart

@@ -42,7 +42,7 @@ void main() {
     );
 
     test(
-      'should throw a CacheExeption when there is not a cached value',
+      'should throw a CacheException when there is not a cached value',
       () async {
         // arrange
         when(mockSharedPreferences.getString(any)).thenReturn(null);

test/features/number_trivia/data/datasources/number_trivia_remote_data_source_test.dart

@@ -16,6 +16,9 @@ void main() {
   NumberTriviaRemoteDataSourceImpl dataSource;
   MockHttpClient mockHttpClient;
 
+  final tNumberTriviaModel =
+      NumberTriviaModel.fromJson(json.decode(fixture('trivia.json')));
+
   setUp(() {
     mockHttpClient = MockHttpClient();
     dataSource = NumberTriviaRemoteDataSourceImpl(client: mockHttpClient);
@@ -26,15 +29,18 @@ void main() {
         .thenAnswer((_) async => http.Response(fixture('trivia.json'), 200));
   }
 
+  void setUpMockHttpClientSuccess200Infinity() {
+    when(mockHttpClient.get(any, headers: anyNamed('headers')))
+        .thenAnswer((_) async => http.Response(fixture('trivia_infinity.json'), 200));
+  }
+
   void setUpMockHttpClientFailure404() {
     when(mockHttpClient.get(any, headers: anyNamed('headers')))
         .thenAnswer((_) async => http.Response('Something went wrong', 404));
   }
 
   group('getConcreteNumberTrivia', () {
     final tNumber = 1;
-    final tNumberTriviaModel =
-        NumberTriviaModel.fromJson(json.decode(fixture('trivia.json')));
 
     test(
       '''should perform a GET request on a URL with number
@@ -80,12 +86,9 @@ void main() {
   });
 
   group('getRandomNumberTrivia', () {
-    final tNumberTriviaModel =
-        NumberTriviaModel.fromJson(json.decode(fixture('trivia.json')));
-
     test(
-      '''should perform a GET request on a URL with number
-       being the endpoint and with application/json header''',
+      '''should perform a GET request on a URL with *random* endpoint
+      with application/json header''',
       () async {
         // arrange
         setUpMockHttpClientSuccess200();
@@ -113,6 +116,19 @@ void main() {
       },
     );
 
+    test(
+      '''should throw a ServerException when the response code is 200 (success)
+      but the Trivia number is null (infinity)''',
+      () async {
+        // arrange
+        setUpMockHttpClientSuccess200Infinity();
+        // act
+        final call = dataSource.getRandomNumberTrivia;
+        // assert
+        expect(() => call(), throwsA(TypeMatcher<ServerException>()));
+      },
+    );
+
     test(
       'should throw a ServerException when the response code is 404 or other',
       () async {

test/features/number_trivia/data/repositories/number_trivia_repository_impl_test.dart

@@ -27,6 +27,7 @@ void main() {
     mockRemoteDataSource = MockRemoteDataSource();
     mockLocalDataSource = MockLocalDataSource();
     mockNetworkInfo = MockNetworkInfo();
+
     repository = NumberTriviaRepositoryImpl(
       remoteDataSource: mockRemoteDataSource,
       localDataSource: mockLocalDataSource,
@@ -77,7 +78,7 @@ void main() {
         'should return remote data when the call to remote data source is successful',
         () async {
           // arrange
-          when(mockRemoteDataSource.getConcreteNumberTrivia(any))
+          when(mockRemoteDataSource.getConcreteNumberTrivia(tNumber))
               .thenAnswer((_) async => tNumberTriviaModel);
           // act
           final result = await repository.getConcreteNumberTrivia(tNumber);
@@ -91,7 +92,7 @@ void main() {
         'should cache the data locally when the call to remote data source is successful',
         () async {
           // arrange
-          when(mockRemoteDataSource.getConcreteNumberTrivia(any))
+          when(mockRemoteDataSource.getConcreteNumberTrivia(tNumber))
               .thenAnswer((_) async => tNumberTriviaModel);
           // act
           await repository.getConcreteNumberTrivia(tNumber);
@@ -105,7 +106,7 @@ void main() {
         'should return server failure when the call to remote data source is unsuccessful',
         () async {
           // arrange
-          when(mockRemoteDataSource.getConcreteNumberTrivia(any))
+          when(mockRemoteDataSource.getConcreteNumberTrivia(tNumber))
               .thenThrow(ServerException());
           // act
           final result = await repository.getConcreteNumberTrivia(tNumber);

test/features/number_trivia/domain/usecases/get_random_number_trivia_test.dart

@@ -1,7 +1,6 @@
 import 'package:clean_architecture_tdd_course/core/usecases/usecase.dart';
 import 'package:clean_architecture_tdd_course/features/number_trivia/domain/entities/number_trivia.dart';
 import 'package:clean_architecture_tdd_course/features/number_trivia/domain/repositories/number_trivia_repository.dart';
-import 'package:clean_architecture_tdd_course/features/number_trivia/domain/usecases/get_concrete_number_trivia.dart';
 import 'package:clean_architecture_tdd_course/features/number_trivia/domain/usecases/get_random_number_trivia.dart';
 import 'package:dartz/dartz.dart';
 import 'package:mockito/mockito.dart';

test/features/number_trivia/presentation/bloc/number_trivia_bloc_test.dart

@@ -48,11 +48,18 @@ void main() {
         when(mockInputConverter.stringToUnsignedInteger(any))
             .thenReturn(Right(tNumberParsed));
 
+    void setUpMockGetConcreteNumberTriviaSuccess() =>
+        when(mockGetConcreteNumberTrivia(any))
+            .thenAnswer((_) async => Right(tNumberTrivia));
+
     test(
       'should call the InputConverter to validate and convert the string to an unsigned integer',
       () async {
         // arrange
         setUpMockInputConverterSuccess();
+        // MEMO: need add this, or Unhandled error NoSuchMethodError: The method 'fold' was called on null.
+        setUpMockGetConcreteNumberTriviaSuccess();
+
         // act
         bloc.add(GetTriviaForConcreteNumber(tNumberString));
         await untilCalled(mockInputConverter.stringToUnsignedInteger(any));
@@ -83,8 +90,7 @@ void main() {
       () async {
         // arrange
         setUpMockInputConverterSuccess();
-        when(mockGetConcreteNumberTrivia(any))
-            .thenAnswer((_) async => Right(tNumberTrivia));
+        setUpMockGetConcreteNumberTriviaSuccess();
         // act
         bloc.add(GetTriviaForConcreteNumber(tNumberString));
         await untilCalled(mockGetConcreteNumberTrivia(any));
@@ -98,8 +104,8 @@ void main() {
       () async {
         // arrange
         setUpMockInputConverterSuccess();
-        when(mockGetConcreteNumberTrivia(any))
-            .thenAnswer((_) async => Right(tNumberTrivia));
+        setUpMockGetConcreteNumberTriviaSuccess();
+
         // assert later
         final expected = [
           Empty(),

test/fixtures/trivia_infinity.json

@@ -0,0 +1,6 @@
+{
+  "text": "Test Text",
+  "number": null,
+  "found": true,
+  "type": "trivia"
+}