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 Person class. In main(), we create a Person object p1, go through lots of code, and then want to work with p1 again, possibly in a different method of another class. How do we know that p1 still references a Person object? In the previous snippet...