[C# and Win8] How to develop your first Modern UI application Part 3: Function declarations & Windows Store Deployment

In the last part we saw how to develop our first Windows 8 Modern UI application. I showed you how to create a very basic Image Viewer application. This part will show how to use system features (such as access to system resources or external devices) and how to deploy your applications via the Windows Store.

Application Manifest for Windows 8 Modern UI Applications

By default Modern UI applications do not have any access rights to system resources or external devices. You have to specifically allow and authorize those operations within the Application Manifest. In our example we had to edit the Package.appxmanifest file, as explained in the last blog post.

This declaration is especially important if you want to add your applications to the Windows Store. In fact, during the acceptance process, Microsoft verifies that the available functionalities are fully mentioned in your application description.

This is done to assure that everything is coherent, because Users need to know what access rights are required, if they want to install your applications from the Windows Store. Then they are able to decide if they want to download and buy your applications.

There are mainly two types of functionalities, for which access rights can be declared in the Application Manifest :

• General functionalities : Media Files, Pictures Library, Removable Storage, Microphone, Webcam, Localization, Internet Connection, etc...

• Advances functionalities : My Documents, Enterprise Authentication, Certificates, Share Targets, Background Tasks, etc...

You have to know that if you provide access to the advanced functionalities, then Microsoft will analyze your application in more details before your it can be made available on the Windows Store.

Windows Store Deployment

The Windows Store is the centralized and unique software distribution platform for Windows 8 applications. Customers find all sorts of Modern UI applications in the store. You can get more information here: http://www.windowsstore.com.

As already mentioned, applications are validated before they can be distributed via the store. This allows a high quality and controlled security access for all applications present on the store. There is a whole acceptance process, that each application has to comply on before it can be put on the Windows Store. It assures that applications work correctly, that they use only the accesses that are declared in the application description and that they comply to certain Modern UI design rules.

The validation is done by specialized Microsoft teams. It includes a thorough technical review, which aims at prohibiting malwares and viruses as well as unnecessary security accesses. Thus, a Windows Store customer may be confident to buy anything from the store without any risks of bad impact on his system.

Before you can distribute you applications on the store, you have to create a user account within the Dev Center for Windows Store Apps :  
http://msdn.microsoft.com/en-us/windows/apps.

The are two types of user accounts: individual accounts and enterprise accounts. You have to know that only enterprise accounts can submit applications using advanced functionalities.

After the account creation you are now able to submit your first application to the Windows Store via the the “Submit an App” button. Choose a name for you application, enter a meaningful description and apply for the technical review.

After Microsoft has validated and tested your application it will be available on the Windows Store. That’s it you are now ready to build you own Windows 8 Modern UI application and distribute on the Windows Store.

[C# and Win8] How to develop your first Modern UI application Part 3: Function declarations & Windows Store Deployment

[C# and Win8] How to develop your first Modern UI application Part 2: Source Code & Development

In the last part we discussed how to create your first Modern UI project and all the prerequisites for being able to start its development. In this part you will actually see, what developing this type of application really means.

Development of the Image Viewer application

For this tutorial we are going to create an Image Viewer application. The goal of this example application will be to display all the images in your local Pictures Library. You may reuse the skeleton project, that we have created at the end of the last blog post and apply the following steps to it.

Add some code that gets data from your local Pictures Library and execute your application. A best practice in Modern UI applications is to always use an asynchronous approach, which is why we use the GetFilesAync() method and the await keyword in the following example :

You will see that there is an exception of type “System.UnauthorizedAccessException” :

Modern UI application do not have any access rights by default, which is why you get an error message, when trying to access your local Pictures Library.

So as first step you have to allow access to your Pictures Library. To do this you just have to double-click on the “Package.appxmanifest” file in the Solution Explorer. Then go to the Capabilities section and enable the checkbox “Pictures Library”. Save your modifications and there should not be any error message anymore, when you execute your application.

In the next step, add a new class ImageItem to the solution and implement the following code :

This class will be instantiated for each picture in your local Pictures Library. It contains the picture itself, the picture name and a short description.

Add a GridView to the “MainPage.xaml” file, that is going to be used for displaying the pictures from the local Pictures Library :

Here is an example implementation of the whole code that could be implemented for the Image Viewer application in the “MainPage.xaml.cs” file :

When executing the application, you will get a display of all the pictures that are currently stored in your local Pictures Library :

If there are no pictures you will get a message that there were no pictures found :

This concludes this part. I am going to show you how to further configure your applications in more detail, as well as how to publish them in the next parts of the series.

[C# and Win8] How to develop your first Modern UI application
Part 2: Source Code & Development

[C# and Win8] How to develop your first Modern UI application Part 1: Prerequisits & Project Creation

This tutorial is going to show you how to develop Modern UI applications (also called Metro-style applications). You will see the different steps such as creation and configuration of the project, the development using Visual Studio 2012 and its deployment on the Windows Store.

Modern UI applications can be developed using multiples languages. So if you are experienced in web development (HTML5/CSS3), .NET application development (XAML/C#, VB, or C++) or DirectX application development (C++), you already have the necessary skills to develop your first application.

There are multiple display modes for Modern UI applications. You should know that by default they are border-less and full-screen (but you may change that).

Modern UI applications may currently only run on the Windows 8 and Windows 2012 operation systems. But they are running on all devices that are compatible with those operation systems (Desktop PCs, Laptops, Tablets, etc…).

Prerequisites for Modern UI applications

To be able to develop you first Modern UI application you have to have some prerequisites in place. Here are the technical requirements :

• Windows 8 (Professional or Enterprise) / Windows Server 2012
• Visual Studio 2012 (Professional or Ultimate)
• Developer License (see below)

That is all ! After installation of those products you are now able to create your first Modern UI application project.

Project Creation

Start Visual Studio 2012, make sure that .NET Framework 4.5 is selected and click on “New Project” (you may also do this from the menu by clicking on “File” / “New” / “Project”). Create a new project of type “Blank App (XAML)”, which you may find under the “Windows Store” section.

If this is the first time you have ever created a Modern UI application, you will not have a valid developer license for Windows 8. But this is really no problem, since you may ask for one for free.

You now have to connect yourself with a valid Windows Live account, then the system will present you with the following dialog. Just click on “I Agree” and the developer license will be downloaded to your system.

If you already had a license but it is not valid anymore (licenses are currently only valid during 1 month), then you have to renew it. For being able to develop Modern UI applications you have to have a valid developer license all the time.

The skeleton of your new application gets now generated. In the next parts of the series we will continue with the actual development of the application and see how to debug and in the end deploy it.

[C# and Win8] How to develop your first Modern UI application
Part 1: Prerequisits & Project Creation

[Tutorial] Test Driven Development with Visual Studio 2012 Part4: Full cycle of TDD using Visual Studio 2012

The last blog post in the series introduced some of the new features within Visual Studio 2012, applicable to Test Driven Development (TDD). This blog post is going to show you how to practically use all of those new features and apply them to Test Driven Development. You are going to see a full cycle of TDD using Visual Studio 2012, during the implementation of a simple calculator example!

Phase 1: Write a unit test for a new functionality  

Respecting the Test Driven Development approach, you have to create your unit tests before starting with any implementations. In our example we have to write some unit tests for the methods “Addition” and “Multiplication”. But first of all, we have to add a project of type “Unit Test Project” to our solution (if you do not already have one).

You may now add the necessary unit tests.Here is an example of the unit tests you could add based on the unit test framework NUnit:

Please note that the “Calculator” class and its methods “Addition” and “Multiplication” do not exist at this stage yet.

Visual Studio 2012 provides the possibility to generate the missing code in an automatic way. For that you just have to right-click on the “new Calculator” definition in the unit test project and choose to generate the class via the “Generate/New Type“ option in the menu.

A wizard opens and you are now able to configure multiple options such as the type (classe, struct, interface, enum), the access (public, internal), the destination project and the file name for the generation of the missing class.

The next step, after having auto-generated the “Calculator” class, consists of auto-generating the missing methods within this class. This can be achieved in almost the same way as it was done for the missing class. You do a right-click on the method calls "calculator.Addition(…)” and “calculator.Multiplication(…)” in the unit test project and you generate them via the “Generate/Method Stub” option in the menu.

Here is the auto-generated source code of those two methods:

In the last step of this phase you have to open the “Test Explorer” window where you may now execute all your unit tests. This can be done by clicking on the “RunAll” button or by using the already explained “Post Build Test Runs” option (see the previous blog post in the series).

As expected your unit tests will fail, since the corresponding source code has not been implemented yet. We will see how to do that in the next phase.

Phase 2: Implement the minimum code necessary to pass the test

Now in this phase, the only thing that needs to be done, is to implement the expected functionalities. The idea is to develop the minimum code necessary, which responds to the functional requirements. Everything that concerns optimization and amelioration must not be addressed since it will be treated later in the next phase (refactoring).

Following the implementation you may now restart your unit tests by clicking on the “RunAll” button or by using the already explained “Post Build Test Runs” option (see the previous blog post in the series). Your should see that you unit tests have been terminated successfully. If this is not the case you have to review your code and iterate until all of your unit tests pass successfully.

At this stage the source code corresponds exactly to the functional needs and it provides the expected behavior. The final project structure includes a unit test project as well as an application implementation project.

But the source code might not be optimized. Its quality might not adhere to your quality standards, so it has to be ameliorate. The refactoring can be done without any problems since the unit test assure that there are no regressions. Moreover, regressions can be detected very quickly and thus can be handled as soon as possible. This is going to be explained in the next phase.

Phase 3: Refactor and optimize the source code

The process of improving your source code after the initial implementation phase (Phase 2)  is called “Refactoring”. The source code structure is modified internally without any modifications to the external behavior (very important!!). A source code that just “works” is now transformed into a source code that works in an optimal way. Most of the time, the resulting source code is executing with better performance, using less memory and/or with a better software design.

The refactoring consists of the following steps (non-exhaustive list):

• Detect and eliminate all code duplication
• Limit complexity and the number of classes
• Simplify and optimize method algorithms
• Relocate, rename and harmonize methods
• Improve code readability
• Remove not used code (also called “dead code”)
• Add comments to complex code sections

In our simple example there is nothing to be refactored, since there are neither enough methods nor enough classes. But this last step has to be done in bigger developments at the end of each cycle. Afterwards, a new development cycle starts with  new functionalities from Phase1 on.

[Tutorial] Test Driven Development with Visual Studio 2012
Part4: Full cycle of TDD using Visual Studio 2012

[Tutorial] Test Driven Development with Visual Studio 2012 Part3: New features in Visual Studio 2012 (2/2)

The last blog post in the series introduced some of the new features within Visual Studio 2012, applicable to Test Driven Development (TDD). This blog post is going to continue to further present some more features of Visual Studio 2012 in this domain.

Management of unit tests via Test Explorer

The first impression when opening the “Test Explorer” window is a very positive one. Here are the principal changes when compared to Visual Studio 2010:

• The “Test View” and “Test Results” windows have been deleted and consolidated into the “Test Explorer” window. This is going to streamline the interaction between development (the code) and tests.
• The interface is simple but efficient: all information is accessible via a simple mouse click in a very intuitive way.
• Unit tests are grouped by their status (failed, passed,…), failed tests are shown on top, a double mouse click allows for accessing the code source of a test (no need to open an external window anymore).
• It is now much easier to execute a code coverage analysis. In previous versions this was not handled in a very intuitive way, since you had to create a configuration file, start the analysis via the Visual Studio menu and then open the adequate results window. In Visual Studio 2012 everything was consolidated and is now integrated in the “Test Explorer” interface.

Post Build Test Runs

A best practice when adhering to TDD principles is to execute unit tests as soon and as much as possible for being able to identify bugs, misbehaviors and regressions. There is a new feature, called “Post Build Test Runs”, in Visual Studio 2012, which allows for automatically unit test execution after each compilation. The feature can either be activated via the menu under “Test/Test Settings” or directly from within the “Test Explorer” window. When using this features, unit test are executed on a separated and dedicated thread, so there is no impact on developer efficiency.

Migration of unit tests from Visual Studio 2010 to Visual Studio 2012

As you might know, there a multiple difficulties and bugs, when migrating unit tests from Visual Studio 2008 to Visual Studio 2010, because the migration is not very transparent and sometimes even somewhat complex. In some cases you even have to migrate to the .NET 4.0 Framework to make everything work correctly!

I can assure you that there are no such migration problems, when trying to migrate from Visual Studio 2010 to Visual Studio 2012. This is partly due to the fact that most of the unit test components are the same between those two versions of Visual Studio. The library is still Microsoft.VisualStudio.QualityTools.unitTestFramework.dll in its version 10.0.0.0, which is still based on .NET runtime v2.0.50727.

Fakes Framework (Stubs and Shims)

The “Fakes Framework” based on the  “Moles” project, created by the Microsoft Research team, is now exclusively integrated into the “Ultimate” version of Visual Studio 2012 (and sadly only in this version!).

The goal of this framework is to aid development teams in producing unit tests rapidly and easily. For this, the “Fakes Framework” adds 2 notions:

• Stubs: they provide automatic mock implementations of interfaces or abstract classes, that can be used in unit tests for being able to isolate parts that need to be unit tested.
• Shims: they allow for runtime interception and redirection of method calls to specific objects. For example , they may be used to mock objects, which normally can’t be mocked due to access restrictions in the .NET framework. By using Shims it is possible to redirect calls to these objects with calls to objects that provide your own implementations.

There are however some restrictions. One restriction is that classes included in the “mscorlib” namespace cannot have any “Fake Assemblies”. Unfortunately, you cannot create any Shims for the “System.Configuration.ConfigurationManager” class for example.

The “Fakes Framework” provides some real advantages, when compared to existing mock testing frameworks such as RhinoMock, because developers do not need to modify their functional code for being able to execute unit tests.

In my next blog post I am going to show you how to practically use all of those new features and apply them to Test Driven Development. You are going to see a full cycle of TDD using Visual Studio 2012 !

[Tutorial] Test Driven Development with Visual Studio 2012
Part3: New features in Visual Studio 2012 (2/2)

[Tutorial] Test Driven Development with Visual Studio 2012 Part2: New features in Visual Studio 2012 (1/2)

The last blog post in the series introduced Test Driven Development (TDD). This blog post is going to talk about some of the new features in Visual Studio 2012, that allow you to successfully apply the TDD approach in your daily work.

Visual Studio 2012 external test framework support

The previous version Visual Studio 2010 already provides the possibility of using external test frameworks. But unfortunately with multiple limitations such as:

• Dependency on third party applications for being able to execute unit tests. For example Gallio needs Icarus Runner if you want to run your unit tests.
• Code coverage analysis does not work natively, only by using third party products (such as NCover for example).
• Execution of unit tests is specific to certain plugins : for example there is a difference if you run your MSTest unit tests from within Visual Studio 2008 or by using Resharper, which may result in problems when trying to apply continuous integration processes.

As you can see, you have to multiply plugins and tools, that might not always be compatible with each other, when using Visual Studio 2010 with external test frameworks. Really not an optimal situation, when you want to benefit from specialized external test frameworks and their advanced functionalities !

One of the major updates of Visual Studio 2012 is the support of several external unit test frameworks for multiple languages without any of the limitations mentioned above.

Here are some of the unit test frameworks that you can now use easily:

For .NET :

• NUnit (http://nunit.org)
• xUnit.net (http://xunit.codeplex.com)
• MBUnit (https://github.com/Gallio/Gallio-VS2011-Integration)

For Javascript/HTML :

• QUnit & Jasmine (http://chutzpah.codeplex.com)

For C++ :

• MSTest Native (http://aka.ms/mstest-native-vs11)

How to use NUnit as external test unit framework 

Lets see how to use NUnit as external test unit framework. First you have to install NUnit (currently as Prerelease) via NuGet.

Then you have to install the test adapter plugin for NUnit (currently as Beta) via the Extension Manager, which you can now find under “Tools/Extensions and Updates…”. Note that all test adapters are free of charge and that the functionality to search and download those adapters is fully integrated in Visual Studio 2012.

After installing the NUnit test adapter plugin, you are able to use all Visual Studio 2012 unit test functionalities together with NUnit. You may for example execute your NUnit unit tests directly from within the Visual Studio 2012 IDE, display the test results in the standard view “Test Explorer” and run a code coverage analysis on your code.

Support for C++ in native MSTest

Another big feature of Visual Studio 2012 is that it now supports native MSTest unit tests for C++ applications. Good news for C++ developers, who may now also apply Test Driven Development using native MSTest as unit test framework.

Following is an example implementation of a unit test in Visual C++ using the native MSTest unit test framework:

Support for async and await in VS 2012 and its unit test framework

Windows 8 and .NET 4.5 introduce a major feature that will have a high impact on software development as we know it: Asynchronous Programming. Visual Studio 2012 and its unit test framework support this new approach perfectly. The async and await keywords, available in .NET 4.5, may now be used for creating unit tests of asynchronous methods.

Lets say that you want to create a unit test for the following asynchronous example method:

The corresponding NUnit test method could be:

In my next blog post I am going to further show you other new features of Visual Studio 2012, which will make your life easier when trying to apply Test Driven Development.

[Tutorial] Test Driven Development with Visual Studio 2012
Part2: New features in Visual Studio 2012 (1/2)

[Tutorial] Test Driven Development with Visual Studio 2012 Part1: Introduction to TDD

In one of my blog posts series, I showed you how to increase the quality of your code and how to make it much easier to maintain by applying the S.O.L.I.D. principles. I then focused on the Liskov Segregation Principle (LSP) by using Code Contracts in .NET 4.0. This blog series is going to talk about Test Driven Development (TDD) in an Agile environment using the latest Visual Studio 2012 features and how that is going to help you to be more efficient and productive.

The goal of this series will be to show you some of the new features within Visual Studio 2012, that are going to help you when trying to apply the TDD approach. The first parts of the series are more theoretical, while as the last part will be fully practical, since we are going to implement some example code using TDD.

Contrary to traditional software development methodologies and processes, where writing unit test is often done as last step after code implementation, TDD consists of writing unit test upfront as first step in the software development cycle. No development can be started without having implemented the corresponding unit tests. You understand that TDD has large impacts on the organization of your teams.

The following are the different steps when applying Test Driven Development :

1. Write a unit test for a new functionality, then validate that the test fails, since its implementation has not been realized
2. Implement the minimum code necessary to pass the test, then validate that the test passes successfully, meaning that the expected behavior is now provided by the implementation
3. Refactor and optimize your code, the unit tests ensure the coherence of the functionalities

Using TDD helps in obtaining a code source that is very reliable, predictable, robust - and after refactoring - highly optimized. Unit tests ensure a correct behavior, independently from where it is going to be used, resulting in a code source that will work as expected under any circumstances.

For being able to create good unit tests, you have at first to think about the conception and software design of your application. You must not hurry into doing your implementations, before being clear about your objectives (which should be true for any development, but sadly often it is not).

Conceptual errors can be detected and resolved much quicker and in a much more efficient way. As explained the implementation is started only after the conceptual phase has been validated and tested via thorough unit tests. In this case, your unit tests become much than just tests. They become some sort of general specification, describing  “units of functionality” for your application.

When refactoring and optimizing your code, you may restructure your code without any risks, since all your modifications are now verifiable. Unit tests ensure that there are no technical or functional regressions and furthermore the coherence of behavior. They validate that your application will always behave in the same way, if they are executed with success.

Additionally if you combine TDD with Extreme Programming (XP) and pair programming, you obtain a code with a very high degree of quality.

The next blog post in the series is going to talk about some the new features in Visual Studio 2012, that allow you to apply TDD quickly and easily, stay tuned!

[Tutorial] Test Driven Development with Visual Studio 2012
Part1: Introduction to TDD

[C# and EF] Tutorial: Entity Framework Code First Migrations 2/2

This second part of the series shows how to activate EF Code First Migrations and either handle them manually in code or – even more interesting - letting EF handle them automatically for you.

Manual Code-based EF Code First Migrations

The first possibility is to handle those changes manually from within your code. Here is how that works.

• Open the Package Manager Console from the Tools menu within Visual Studio 2012.

• Activate the manual EF Migration features by entering the command “Enable-Migrations”.

• This adds a new folder Migrations and also the auto-generated classes Configuration.cs  and [SOMEDATE]_InitialCreate.cs to your project.

• The Configuration.cs class allows you to configure the EF Code First Migrations options and seed data after migration (very useful for testing purposes during development).

• The other class contains all the code necessary to create the database (Up) and also drop it (Down) if necessary.

• Here is an example of what can be found in the Up() method.

• Here is an example of what can be found in the Down() method.

From here you may start to implement you own code in C# for handling EF Code First and database schema changes.

Automatic EF Code First Migrations

Being able to handle database schema changes related to EF Code First changes from C# code is great, you won’t need to be an expert of database development anymore. But you still need to know what to change and you still need to allocate some time for it.

What if there would be a fully automated way of handling those changes without any effort? Well there is and you just have to activate it. Here is how that works.

• Open the Package Manager Console from the Tools menu within Visual Studio 2012.

• Activate the automatic EF Migration features by entering the command “Enable-Migrations -EnableAutomaticMigrations”.
• If you try that on a project where you have already activated the manual EF Code First features, you just need to delete the Migrations folder first.

• If you look into the Configuration.cs file you will see that the flag to activate automatic migrations is now enabled.

• When you now change the EF Code First model as explained in the first post of the series, you may start the automatic migration of the database via the Package Manager console by entering “Update-Database”.

• And you see that the automatic migration was not applied because it would result in data loss. By default it is not allowed to apply automatic migrations if there is data loss implied. This is a security feature to not accidently delete important data from the database. Mind that you may revert back to an old database schema but you won’t get back deleted data!
• So now it is up to you to either review the changes or allow automatic migrations if there is data loss (really use this with percaution!!).
• To allow data loss you just set the flag AutomaticMigrationsDataLossAllowed to true in the Configuration constructor.

• When you restart the automatic migration of the database via the Package Manager console by entering “Update-Database” (you may want to add the “–Verbose” flag) you see all the changes that were applied.

• You can now use your application as expected. The modifications in the database reflect the EF Code First model changes.

[C# and EF] Tutorial: Entity Framework Code First Migrations 2/2

[C# and EF] Tutorial: Entity Framework Code First Migrations 1/2

I showed you how to use the Entity Framework Code First approach in one of my last blog posts. This approach is very useful if you want to begin with the implementation and there is no database yet. You want to concentrate on the code and not worry about the database at all, therefore letting Entity Framework auto-generate the database for you.

This is especially interesting for developers not having too much experience in database development or in cases where you have to deliver very quickly and you just don’t want to bother with database design.

The problem : Lack of handling Code First model changes in the DB

Code First works very well and is very easy to use. But it lacks an important feature as I have already pointed out in one of my other blog posts – the handling of database schema changes (add/delete/modify columns, add/delete/modify data types, add/delete/modify constraints, etc…) related to EF Code First model changes .

When you change the underlying EF Code First model expressed in your code (via POCO classes for example) and/or its restrictions you either have to re-create the whole database, meaning that all your data gets lost in the process (not acceptable in production use), or code the database changes manually via SQL upgrade scripts.

In this case the developer still needs to have good database development skills and spent time to create, test and execute the upgrade scripts. This is a tedious task, which the new version of Entity Framework 5.0 integrated in .NET 4.5  is going to greatly simplify and automate.

The solution: Code First Migrations

Microsoft heard the customer requests concerning this problem and added what is called Entity Framework Migrations. It is very easy to activate, and though not perfect, serves very well for applying necessary database schema changes if you work with EF Code First.

Let me show you how it works by providing an example in Visual Studio 2012.

• Create a new project (for the example a console project but you may as well use any other type of project).

• Now do a right click on the project in the Solution Explorer and select to manage the NuGet packages for it.

• In the Nuget packages window search for Entity Framework and select version 5.0 (currently as a release candidate, this won’t be necessary in the future since it will be fully integrated in .NET 4.5).

• This will allow you to use Code First and do an example implementation : a POCO class Person.
• When you run your application and use the DataContext, the database and all its columns and constraints get automatically generated. Everything works fine and your application works as expected.

• Now you get an application change request and you decide to change the EF Code First model by changing the POCO class.

• But if you try to change the underlying POCO classes of an already generated database and execute your application, you will get the following exception.

• This is the expected behavior since the new EF Code First Migrations features are not activated by default. You have to activate them manually and configure them according to your needs.
• To do this open the Package Manager Console from the Tools menu within Visual Studio 2012 and activate the EF Code First Migration features from there.

In the next part of the series I am going to explain how to activate either the manual or the automatic features of EF Code First Migrations so stay tuned.

[C# and EF] Tutorial: Entity Framework Code First Migrations 1/2