Matthew Leibowitz: UI Testing for Indie Xamarin Devs

In the Xamarin 4 announcement, there were hundreds of improvements, but some of the most exciting points for indie devs included free access to UITest and Xamarin Insights.

I noticed especially well-received comments during my presentation at the Gauteng Xamarin User Group. Typically South African indie devs complained about high prices, especially due to the exchange rate being very unfavourable.

And this is not just for South Africans; Indie devs don’t usually have large amounts of money to throw at Unit Testing frameworks. They might just grab the best free tool out there. And now, Xamarin has become that “best” and “free” tool.

Xamarin.UITest

I think Xamarin.UITest is the best automated UI testing framework currently available. It takes two tried-and-tested frameworks: NUnit and Calabash and merges them to create a excellent C# API for controlling mobile apps.

Not only does UITest make testing easier, we can also test on both devices and simulators at no additional cost. No extra configuration is needed either. When the project is compiled, the test appear in the IDE’s Unit Test panel. From there, the tests can be run as any other unit test.

I installed the NUnit Test Adapter for Visual Studio as this IDE can’t run NUnit tests natively.

Simple Example

Using UITest is very easy, and just requires that the interaction is described using C# code. The actual flow of the code is the same as if you had actually performed the actions on the device.

Lets take an example test case – making sure a credit card number is valid. We would first want to make sure that the text field is clear before entering the number. Then, after the keyboard is hidden, we want to start the validation. Finally, we need to ensure that the error message appears.

In this test, failure comes if the error message does not appear at all, or if the screen changes.

// clear credit card numberapp.ClearText("CreditCardNumber");// enter a card numberapp.EnterText("CreditCardNumber", "123456789123456");// make sure the keyboard is goneapp.DismissKeyboard();// tap the validate buttonapp.Tap (c => c.Button ("ValidateCreditCard"));// make sure that the error message appearsapp.WaitForElement(c => c.Marked("Credit card number is invalid."));

Xamarin Test Recorder

Xamarin recently announced the Xamarin Test Recorder, a preview tool that makes writing mobile UI tests even easier.

Instead of writing this test by hand from scratch, we can make use of the recorder to interact with the app. While we do this, the recorder writes out the steps in C# code. We can then take this code and add it to our test project.

Although the recorder is not perfect yet, we can still use the code and just tweak it a bit. I found that sometimes the recorder wasn’t able to pick up when I had tapped on switches or sliders, but this can be changed. If the element has an ID, then we can swap out the code that tries to find the element by UI index with code that finds the element by ID.