Dart: Scalable Application Development

Microtesting your code with assert

Writing tests for your app is necessary, but it is not productive to spend much time on trivial tests. An often underestimated Dart keyword is assert, which can be used to test conditions in your code.

How to do it...

Look at the code file microtest.dart, where microtest is an internal package as seen in the previous recipe:

import 'package:microtest/microtest.dart';

void main() {
 Person p1 = new Person("Jim Greenfield", 178, 86.0);
 print('${p1.name} weighs ${p1.weight}' );
 // lots of other code and method calls
 // p1 = null;
 // working again with p1:
 assert(p1 is Person); 
 p1.weight = 100.0;
 print('${p1.name} now weighs ${p1.weight}' );
} 

We import the microtest library, which contains the definition of the ...