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


• How to write it


• How to write it
• Integration Test vs Unit Test


• How to write it
• Testing tools for WP7


• How to write it
• The first test


• How to write it
• 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



• 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

9


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.

10


Classic wp7 approach
• Code coupled with UI
– Xaml + Code Behind -> one class

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

11


Classic wp7 approach

Your code is
NOT TESTABLE!

12


MVVM Approach
•Architectural Pattern
•Derived from Presentation Model
pattern (Fowler)
•Clear separation between UI and Logic

UI ViewModel

Collections, DelegateCommand, Properties

13


MVVM Approach
• Code structure:
– ViewModel (c#): Logic
– View (Xaml): Presentation
– No more code behind

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

14


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!

15


Test Runner
• NUnit

• Resharper

• Test Driven.net

16


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

• Error if the image is not in 4:3

17


Solution structure
WP7 App

View
ViewModel

WP7 Class Library

NUnit Library (via NuGet)

TestSuite

18


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; }

}
}
}

19


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);
}
}
}

20


First test
[MethodName]_[StateUnderTest]_[ExpectedBehavior]

[Test]
{
var viewModel= new MainViewModel();

viewModel.Height = 100; Arrange objects.
Act on an objects.
bool result = viewModel.RatioCheck;
Assert something expected.
Assert.IsFalse(result);
}

21


Run test

22


Refactor our test
[TestFixture]
{
private MainViewModel viewModel;

[SetUp] executed before every test
public void SetUp()
{
viewModel = new MainViewModel();
}

[Test]
{

Assert.IsFalse(viewModel.RatioCheck);
}
}

23


Refactor our test
[TestFixture]
{

[Test]
{

}

[TearDown]
public void TearDown()
{
viewModel=null; executed after every test
}
}

24


Run test again

25


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;

}

26


Some more cases

27


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;
}
}
}
}

28


Run tests

29


Test Driven Development

• We just made it!

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

30


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;

}

31


• 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.

32


What to test in WP7
• Properties with logic (not only get/set)
• Command
• Navigation between pages
• Interaction with storage
• Converter
• Event

33


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

34


Recap
• How to write it
• Testing tools
• The first test
• Maintaining test suite

35


Be in contact
Mail: michele@orangecode.it
Twitter: @piccoloaiutante
Web: www.orangecode.it
Blog: www.orangecode.it/blog
GitHub: https://github.com/piccoloaiutante

Community: WEBdeBS

36


Grazie a
DotNET Lombardia!

37


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