Getting started with Windows Phone 7 and unit test

Getting started with Tests on your WP7 App

Friday, June 29, 2012

Who am I?

• Developer freelance:–C# Asp.net Mvc, Wpf, Wp7–Python Django–Blog: orangecode.it/blog

What we’re going to see

•What is a unit test

•What is a unit test• How to write it

•What is a unit test• How to write it• Integration Test vs Unit Test

•What is a unit test• How to write it• Integration Test vs Unit Test• Testing tools for WP7

•What is a unit test• How to write it• Integration Test vs Unit Test• Testing tools for WP7• The first test

•What is a unit test• How to write it• Integration Test vs Unit Test• Testing tools for WP7• The first test• Maintaining test suite

Let’s start

From Wikipedia

• A unit test is a piece of a code (usually a method) that invokes another piece of code and checks the correctness of some assumptions afterward. • If the assumptions turn out to be wrong, the unit test has failed. • A “unit” is a method or function.

Good test properties• It should be automated and repeatable. • It should be easy to implement. • Once it’s written, it should remain for future use. • Anyone should be able to run it. • It should run at the push of a button. • It should run quickly.

Roy Osherove

Good test properties

• If your test doesn’t follow at least one of the previous rules, there’s a high probability that what you’re implementing isn’t a unit test.

• You’ve done integration testing.

Integration Test

• Integration testing means testing two or more dependent software modules as a group.

First Test

Unit vs Integration Test

• integration test: test many units of code that work together to evaluate one or more expected results from the software.

• unit test: test only a single unit in isolation.

Classic wp7 approach

• Code coupled with UI– Xaml + Code Behind -> one class

public partial class MainView : PhoneApplicationPage { public MainView() { InitializeComponent(); } }

Classic wp7 approach

Your code is NOT TESTABLE!

•Architectural Pattern•Derived from Presentation Model pattern (Fowler)

•Clear separation between UI and Logic

MVVM Approach

Collections, DelegateCommand, Properties

ViewModel

MVVM Approach• Code structure:

–ViewModel (c#): Logic–View (Xaml): Presentation–No more code behind

• Now the ViewModel (as a plain c# class) IS TESTABLE

Unit Test framework

• Nunit for Windows Phone 7

• No official mocking framework for Windows Phone 7, but I found out that Moq 3.1 for silverlight works!

Test Runner

• NUnit

• Resharper

• Test Driven.net

Context

• Application that resize images• Two boxes for the new size• Ok button

• Error if the image is not in 4:3

Solution structure

WP7 App

ViewModel

WP7 Class Library

NUnit Library (via NuGet)

TestSuite

MainViewModel

namespace OrangeCode.Resizer.ViewModel{ public class MainViewModel { public int Height { get; set; }

public int Width { get; set; }

public bool RatioCheck { get { return Width*3 == Height*4; } } }}

First test

namespace OrangeCode.Resizer.Fixture{ public class MainViewModelFixture { [Test] public void RatioCheck_InvalidSize_ReturnFalse() {

var viewModel= new MainViewModel();

viewModel.Height = 100; viewModel.Width = 80;

bool result= viewModel.RatioCheck;

Assert.IsFalse(result); } }}

First test

[Test]public void RatioCheck_InvalidSize_ReturnFalse(){

var viewModel= new MainViewModel();

viewModel.Height = 100;viewModel.Width = 80;

bool result = viewModel.RatioCheck;

Assert.IsFalse(result);}

[MethodName]_[StateUnderTest]_[ExpectedBehavior]

Arrange objects.

Act on an objects.

Assert something expected.

Run test

Refactor our test

[TestFixture] public class MainViewModelFixture { private MainViewModel viewModel;

[SetUp] public void SetUp() { viewModel = new MainViewModel(); }

[Test] public void RatioCheck_InvalidSize_ReturnFalse() { viewModel.Height = 100; viewModel.Width = 80;

Assert.IsFalse(viewModel.RatioCheck); } }

executed before every test

Refactor our test

[TestFixture] public class MainViewModelFixture { [Test] public void RatioCheck_InvalidSize_ReturnFalse() { viewModel.Height = 100; viewModel.Width = 80;

Assert.IsFalse(viewModel.RatioCheck); }

[TearDown]public void TearDown(){

viewModel=null;}

executed after every test

Run test again

Some more cases

[TestCase(10,10)] [TestCase(12, 12)] [TestCase(0, 0)] public void RatioCheck_InvalidSize_ReturnFalse(int height,int width) { viewModel.Height = height; viewModel.Width = width;

Some more cases

From red to green

namespace OrangeCode.Resizer.ViewModel{ public class MainViewModel { public int Height { get; set; }

public int Width { get; set; }

public bool RatioCheck { get {

if(Width>0 && Height>0)return Width*3 == Height*4;

return false; }

Run tests

Test Driven Development

• We just made it!

• Life Cycle:–Write test (red) –Write logic to pass the test (green)–Refactor code (refactor)–Again..

Back to the first test

[TestCase(10,10)] [TestCase(12, 12)] [TestCase(0, 0)] public void RatioCheck_InvalidSize_ReturnFalse(int height,int width) { viewModel.Height = height; viewModel.Width = width;

Good test properties• It should be automated and repeatable. • It should be easy to implement. • Once it’s written, it should remain for future

use. • Anyone should be able to run it. • It should run at the push of a button. • It should run quickly.

What to test in WP7

• Properties with logic (not only get/set)• Command• Navigation between pages• Interaction with storage• Converter• Event

Final thoughts

• Use small consistent test –One test can test only one feature

• If work with legacy code–create an integration test for every feature–split a integration test in few unit test

•What is a unit test• How to write it• Integration Test vs Unit Test • Testing tools• The first test• Maintaining test suite

Be in contactMail: michele@orangecode.itTwitter: @piccoloaiutanteWeb: www.orangecode.itBlog: www.orangecode.it/blogGitHub: https://github.com/piccoloaiutante

Community: WEBdeBS

Grazie aDotNET Lombardia!

Getting started with Windows Phone 7 and unit test

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