Man on the Moon - 6/7

Part - 5 is here.

PPP template for Unit Tests

The proof of the pudding is in the eating. TDD needs no endorsement, but PPP is not a theoretical proposal either. Unit testing is blessed with a default template for PPP coding. The next time you have to write a unit test and are unsure of how to code it, use the following ‘AAA’ template:

void unitTestWithADescriptiveName() {
	// Arrange
	// Act
	// Assert
}        

In this template, the comments are at the level of intent. You have just described what you want to do, which is:

1. Arrange the object you want to test;
2. Act on the object; and
3. Assert that the action went as expected.

It’s that simple.

The developer who has to read this code after he finds that his changes are causing a unit test failure will understand very clearly what functionality his change has broken.

Now, for each comment, you either have to write a single line, or 3-5 lines, or a single method call to a refactored method. So, let’s say you want to test that pushing the fire button of the rocket will result in a lift-off. The PPP in the unit test can go as follows:

void testPushingFireButtonResultsInLiftOff () {
	// Arrange - Get a rocket with some payload.
	// Act - Push the fire button.
	// Assert - Rocket has lifted off.
}        

Part - 7 is here.