Merge pull request #6 from samuelematias/lesson6

Lesson 6

README.md

@@ -14,6 +14,8 @@ Calculator - [Caster.IO](https://caster.io) project to showcase testing techniqu
 
 [Lesson 5: Using expect() in your tests](https://caster.io/lessons/lesson-5-using-expect-in-your-tests) 👉🏾 [Branch](https://github.com/samuelematias/calculator_app/tree/lesson5)
 
+[Lesson 6: All you need to know about Matchers](https://caster.io/lessons/lesson-6-all-you-need-to-know-about-matchers) 👉🏾 [Branch](https://github.com/samuelematias/calculator_app/tree/lesson6)
+
 ## License
 
 ```

packages/calculator/test/calculator_test.dart

@@ -2,11 +2,19 @@ import 'package:calculator/calculator.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
+  test('Calculator creates a non null object', () {
+    expect(Calculator(), isNotNull);
+  });
+
+  test('the calculator returns an double number when adding 2 and 2', () {
+    final calculator = Calculator();
+    final result = calculator.add(2, 2);
+    expect(result, isA<double>());
+  });
+
   test('the calculator returns 4 when adding 2 and 2', () {
     final calculator = Calculator();
     final result = calculator.add(2, 2);
-    // A test without expect() is considered a bad practice
-    // in case of error, this "reason" text, will show on stacktrace.
     expect(result, 4.00000, reason: 'It should be exactly 4');
   });
 }