28 February 2014

Android Unit Tests

At my old gig I did unit tests....lots and lots of unit tests. At the mercy of one boisterous kiwi I got pretty good at it too, truth be told I began to really enjoy it. Unit testing (done well) gives you confidence in your code and allows you to make changes reassured that previous functionality won't break.
IMHO Any programmer worth their salt should unit test where possible.

Anyway, I've been in the Android world for some time and haven't really had the chance to start experimenting with unit testing. Thankfully Google has a really good explanation of how to set-up a unit testing environment:


However there's tonnes of information thrown at you there and their Eclipse example focuses on the UI. Now in my experience UI testing with automated tests is tricky. While it's fantastic if you can do it, I've found the UI changes too frequently too maintain automated tests. Business cases are naturally more concerned with the UI so it changes regularly and more often that not their are just too many factors involved. So I've written a very quick demo that focuses just on unit testing code.

The Android App To Be Tested

For the purposes of example I've created a very very simple Android app. Just run through the wizard and create a default app. I called mine myAwesomeAndroidApp. Then add the following method too the MainActivity:

public static boolean validateIsMonth(int month){
    if(month > 0 && month < 13){
        return true;
    return false;

This is the method I want to test, simplest thing I could think of.

The Test Framework.

Eclipse ADT contains a framework for creating stand alone testing apps. This enables you to keep your tests and your deployable app separate. To start a new app goto
New -> Other -> Android Test Project

Follow the wizard through, of course ensuring you select your myAwesomeAndroidApp as the test target. You should now have two projects, the test project having an empty package.
In the empty package create a new class, call it TestValidation.java

Now paste the code in as such:

package com.example.myawesomeandroidapp.test;

import android.test.AndroidTestCase;

public class TestValidation extends AndroidTestCase {

    protected void setUp() throws Exception {

Note the use of extends AndroidTestCase. This is very important and allows us to test Android projects.

Now add the unit tests, again this is a very basic example and you should make this more complicated as neccessary to suit your project and expectations.

    public void testValidation(){
    public void testValidationFail(){

You'll see we are testing our validateIsMonth method in the MainActivity, we're testing a pass case and a fail case. Again basic basic unit tests here but hopefully you get the idea.

If you right click on your project and click Run as -> Android JUnit Test your project should run and Eclipse should switch to JUnit view and show you a beautiful column of green lights indicating your unit tests have all passed :)

Hope this helps and happy testing.

Oh and jokes aside Adam Cameron has done some really awesome work on CFML unit testing, check out his blog for some great examples: http://cfmlblog.adamcameron.me/search/label/Unit%20Testing

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