WPF Drag&drop items in a canvas: communicate between behavior and ViewModel

The source code of the sample application is available at GitHub. It has been strongly inspired by Gong WPF DragDrop and has started life as a copy of another “WPF behavior lab”.

The final goal of the application is to allow a user to freely drag an item in a canvas, and that the items “snap” among themselves, so that the user can align them easily. I’m taking it as an opportunity to learn more about WPF.

The first thing I had to learn was how to create and use custom behaviors. They allow to bind elements from the View into the ViewModel using custom properties.
In “pure” WPF (Blend has different behavior conventions), a behavior is a regular class, with a few conventions to declare a custom property. It is called a Dependency Property. It’s pretty easy to bind a simple value (boolean, integer…), examples are plentiful.

Now, in the view, I want to say “when the user moves this item, this method should be run”, because I want not only the item to move, but also the container to compare the item’s new position to its neighbors. A custom property can be anything a variable can be, but not a method. So, to circumvent this, the behavior must be aware of the ViewModel, but obviously we don’t want to strongly link the behavior with the ViewModel.

The ViewModel will have to implement an interface
The View will be bound to this ViewModel through {Binding}
The Behavior will use this interface’s methods to send messages to the ViewModel

public class DragOnCanvasBehavior
{
    // This declares a "DropHandler" property that we will be able to use in the view
    // The name (xxxProperty) and variable modifiers (public static reaonly) must follow the proper conventions
    public static readonly DependencyProperty DropHandlerProperty =
        DependencyProperty.RegisterAttached(
            "DropHandler",
            typeof(IDragDropHandler),
            typeof(DragOnCanvasBehavior),
            new PropertyMetadata(OnDropHandlerChanged));

    // This will actually "link" to the ViewModel, which should implement IDragDropHandler
    private IDragDropHandler DropHandler { get; set; }

    // This is a convention-required method (Getxxx)
    // It will retrieve the property's value
    public static IDragDropHandler GetDropHandler(UIElement target)
    {
        return (IDragDropHandler)target.GetValue(DropHandlerProperty);
    }

    // This is a convention-required method (Setxxx)
    // It will set the property's value
    public static void SetDropHandler(UIElement target, IDragDropHandler value)
    {
        target.SetValue(DropHandlerProperty, value);
    }

    // This called using the callback of the xxxProperty (overload of DependencyProperty.RegisterAttached)
    // It will be run when the value is changed (meaning that Setxxx might be run multiple times with the same value)
    private static void OnDropHandlerChanged(object sender, DependencyPropertyChangedEventArgs e)
    {
        // cast the usable elements
        UIElement element = (UIElement)sender;
        IDragDropHandler handler = (IDragDropHandler)(e.NewValue);

        // we can now use the elements.
        // for instance, we can assign handlers to the UIElement:
        element.MouseLeftButtonDown += Whatever;
    }
}

public class DragOnCanvasBehavior

{

// This declares a "DropHandler" property that we will be able to use in the view

// The name (xxxProperty) and variable modifiers (public static reaonly) must follow the proper conventions

public static readonly DependencyProperty DropHandlerProperty =

DependencyProperty.RegisterAttached(

"DropHandler",

typeof(IDragDropHandler),

typeof(DragOnCanvasBehavior),

new PropertyMetadata(OnDropHandlerChanged));

// This will actually "link" to the ViewModel, which should implement IDragDropHandler

private IDragDropHandler DropHandler { get; set; }

// This is a convention-required method (Getxxx)

// It will retrieve the property's value

public static IDragDropHandler GetDropHandler(UIElement target)

{

return (IDragDropHandler)target.GetValue(DropHandlerProperty);

}

// This is a convention-required method (Setxxx)

// It will set the property's value

public static void SetDropHandler(UIElement target, IDragDropHandler value)

{

target.SetValue(DropHandlerProperty, value);

}

// This called using the callback of the xxxProperty (overload of DependencyProperty.RegisterAttached)

// It will be run when the value is changed (meaning that Setxxx might be run multiple times with the same value)

private static void OnDropHandlerChanged(object sender, DependencyPropertyChangedEventArgs e)

{

// cast the usable elements

UIElement element = (UIElement)sender;

IDragDropHandler handler = (IDragDropHandler)(e.NewValue);

// we can now use the elements.

// for instance, we can assign handlers to the UIElement:

element.MouseLeftButtonDown += Whatever;

}

The IDragDropHandler interface is very simple. The Moved method will notify the ViewModel that the item has been moved, and the Dropped method that the mouse button has been released.

public interface IDragDropHandler
{
    void Dropped();
    void Moved(double x, double y);
}

public interface IDragDropHandler

{

void Dropped();

void Moved(double x, double y);

}

Now, the behavior will use these methods. To do that, we need to create mouse click and move handlers and assign them to the UIElement. Because the OnxxxChanged method is static, but the click/move handlers are not, we need a way to “memorize” the handlers. We’ll do that through a singleton instance:

public class DragOnCanvasBehavior
{
    // we'll use this singleton instance of the behavior to access the DropHandler and the mouse events
    private static DragOnCanvasBehavior Instance = new DragOnCanvasBehavior();

    // initialize the instance and attach events to the element
    private static void OnDropHandlerChanged(object sender, DependencyPropertyChangedEventArgs e)
    {
        UIElement element = (UIElement)sender;
        IDragDropHandler handler = (IDragDropHandler)(e.NewValue);

        // re-initialize the singleton (otherwise different items will have the same behavior)
        Instance = new DragOnCanvasBehavior();
        // attach the handler to the singleton
        Instance.DropHandler = handler;

        // attach or detach the handler to the element
        // remember that the handler can be removed at run-time, so we need handle null values
        if (Instance.DropHandler != null)
        {
            element.MouseLeftButtonDown += Instance.ElementOnMouseLeftButtonDown;
            element.MouseLeftButtonUp += Instance.ElementOnMouseLeftButtonUp;
            element.MouseMove += Instance.ElementOnMouseMove;
        }
        else
        {
            element.MouseLeftButtonDown -= Instance.ElementOnMouseLeftButtonDown;
            element.MouseLeftButtonUp -= Instance.ElementOnMouseLeftButtonUp;
            element.MouseMove -= Instance.ElementOnMouseMove;
        }
    }

    // when the user starts dragging
    private void ElementOnMouseLeftButtonDown(object sender, MouseButtonEventArgs mouseButtonEventArgs)
    {
        // save the mouse position on button down
        // we only want a diff of the mouse position so we don't care much about which element we use as reference
        this.mouseStartPosition = this.GetMousePositionFromMainWindow(mouseButtonEventArgs);
        ((UIElement)sender).CaptureMouse();
    }

    // when the user stops dragging
    private void ElementOnMouseLeftButtonUp(object sender, MouseButtonEventArgs mouseButtonEventArgs)
    {
        UIElement element = (UIElement)sender;
        element.ReleaseMouseCapture();

        // Send a message to the viewmodel that the mouse button has been released
        if (this.DropHandler != null)
        {
            this.DropHandler.Dropped();
        }
    }

    // while the user is dragging
    private void ElementOnMouseMove(object sender, MouseEventArgs mouseEventArgs)
    {
        // don't do anything if no button is clicked (or there is no handler)
        if (!((UIElement)sender).IsMouseCaptured || this.DropHandler == null)
        {
            return;
        }

        // calculate element movement
        Point mouseNewPos = this.GetMousePositionFromMainWindow(mouseEventArgs);
        Vector movement = (mouseNewPos - this.mouseStartPosition);

        // make sure the mouse has moved since last time we were here
        // (the MouseMove is run in loop while the button is clicked, even if the mouse isn't moving)
        if (movement.Length > 0)
        {
            // save current mouse position
            this.mouseStartPosition = mouseNewPos;
            
            // save the element movement
            Point elementNewPos = this.elementPosition + movement; 
            this.elementPosition = elementNewPos;

            // notify the viewmodel that the element has been moved
            this.DropHandler.Moved(elementNewPos.X, elementNewPos.Y);
        }
    }

    // get the mouse position relative to the main window
    private Point GetMousePositionFromMainWindow(MouseEventArgs mouseEventArgs)
    {
        Window mainWindow = Application.Current.MainWindow;
        return mouseEventArgs.GetPosition(mainWindow);
    }
}

public class DragOnCanvasBehavior

{

// we'll use this singleton instance of the behavior to access the DropHandler and the mouse events

private static DragOnCanvasBehavior Instance = new DragOnCanvasBehavior();

// initialize the instance and attach events to the element

private static void OnDropHandlerChanged(object sender, DependencyPropertyChangedEventArgs e)

{

UIElement element = (UIElement)sender;

IDragDropHandler handler = (IDragDropHandler)(e.NewValue);

// re-initialize the singleton (otherwise different items will have the same behavior)

Instance = new DragOnCanvasBehavior();

// attach the handler to the singleton

Instance.DropHandler = handler;

// attach or detach the handler to the element

// remember that the handler can be removed at run-time, so we need handle null values

if (Instance.DropHandler != null)

{

element.MouseLeftButtonDown += Instance.ElementOnMouseLeftButtonDown;

element.MouseLeftButtonUp += Instance.ElementOnMouseLeftButtonUp;

element.MouseMove += Instance.ElementOnMouseMove;

}

else

{

element.MouseLeftButtonDown -= Instance.ElementOnMouseLeftButtonDown;

element.MouseLeftButtonUp -= Instance.ElementOnMouseLeftButtonUp;

element.MouseMove -= Instance.ElementOnMouseMove;

}

// when the user starts dragging

private void ElementOnMouseLeftButtonDown(object sender, MouseButtonEventArgs mouseButtonEventArgs)

{

// save the mouse position on button down

// we only want a diff of the mouse position so we don't care much about which element we use as reference

this.mouseStartPosition = this.GetMousePositionFromMainWindow(mouseButtonEventArgs);

((UIElement)sender).CaptureMouse();

}

// when the user stops dragging

private void ElementOnMouseLeftButtonUp(object sender, MouseButtonEventArgs mouseButtonEventArgs)

{

UIElement element = (UIElement)sender;

element.ReleaseMouseCapture();

// Send a message to the viewmodel that the mouse button has been released

if (this.DropHandler != null)

{

this.DropHandler.Dropped();

}

// while the user is dragging

private void ElementOnMouseMove(object sender, MouseEventArgs mouseEventArgs)

{

// don't do anything if no button is clicked (or there is no handler)

if (!((UIElement)sender).IsMouseCaptured || this.DropHandler == null)

{

return;

}

// calculate element movement

Point mouseNewPos = this.GetMousePositionFromMainWindow(mouseEventArgs);

Vector movement = (mouseNewPos - this.mouseStartPosition);

// make sure the mouse has moved since last time we were here

// (the MouseMove is run in loop while the button is clicked, even if the mouse isn't moving)

if (movement.Length > 0)

{

// save current mouse position

this.mouseStartPosition = mouseNewPos;

// save the element movement

Point elementNewPos = this.elementPosition + movement;

this.elementPosition = elementNewPos;

// notify the viewmodel that the element has been moved

this.DropHandler.Moved(elementNewPos.X, elementNewPos.Y);

}

// get the mouse position relative to the main window

private Point GetMousePositionFromMainWindow(MouseEventArgs mouseEventArgs)

{

Window mainWindow = Application.Current.MainWindow;

return mouseEventArgs.GetPosition(mainWindow);

}

Now, the behavior is notifying the ViewModel that it is being moved. Let’s handle the movement:

// I'm using Fody.PropertyChanged to implement INotifyProperyChanged
// I'm also using Caliburn.Micro as MVVM framwork

[ImplementPropertyChanged]
public class ItemViewModel : PropertyChangedBase, IDragDropHandler
{
    private readonly IEventAggregator events;

    public ItemViewModel(IEventAggregator events)
    {
        this.events = events;
        this.events.Subscribe(this);

        this.Width = 100;
        this.Height = 100;
        this.X = 0;
        this.Y = 0;
    }

    public int Height { get; set; }
    public int Width { get; set; }
    public double X { get; set; }
    public double Y { get; set; }

    public void Dropped()
    {
      // TODO: do something (probably publish an event)
    }

    public void Moved(double x, double y)
    {
        this.X = x;
        this.Y = y;

        // Notify the container that the item is moved, so that it can calculate snapping
        this.events.PublishOnUIThread(new ItemMovedEvent(this.X, this.Y, this.Width, this.Height, this.ID));
    }
}

// I'm using Fody.PropertyChanged to implement INotifyProperyChanged

// I'm also using Caliburn.Micro as MVVM framwork

[ImplementPropertyChanged]

public class ItemViewModel : PropertyChangedBase, IDragDropHandler

{

private readonly IEventAggregator events;

public ItemViewModel(IEventAggregator events)

{

this.events = events;

this.events.Subscribe(this);

this.Width = 100;

this.Height = 100;

this.X = 0;

this.Y = 0;

}

public int Height { get; set; }

public int Width { get; set; }

public double X { get; set; }

public double Y { get; set; }

public void Dropped()

{

// TODO: do something (probably publish an event)

}

public void Moved(double x, double y)

{

this.X = x;

this.Y = y;

// Notify the container that the item is moved, so that it can calculate snapping

this.events.PublishOnUIThread(new ItemMovedEvent(this.X, this.Y, this.Width, this.Height, this.ID));

}

Now that we have a ViewModel that know when it’s being moved, let’s actually allow the user to move it. First, let’s write a container for the items:

[ImplementPropertyChanged]
public class MainViewModel : PropertyChangedBase, IHandle<ItemMovedEvent>
{
    private readonly IEventAggregator events;

    public MainViewModel(IEventAggregator events)
    {
        this.events = events;
        this.events.Subscribe(this);

        this.Items = new BindableCollection<ItemViewModel>();
    }

    // the items displayed on the canvas
    public BindableCollection<ItemViewModel> Items { get; set; }

    // adds an item to the collection
    public void AddItem()
    {
        this.Items.Add(new ItemViewModel(this.events));
    }

    // fired when an item has been moved
    public void Handle(ItemMovedEvent message)
    {
        // TODO: handle snapping to other elements
    }
}

[ImplementPropertyChanged]

public class MainViewModel : PropertyChangedBase, IHandle<ItemMovedEvent>

{

private readonly IEventAggregator events;

public MainViewModel(IEventAggregator events)

{

this.events = events;

this.events.Subscribe(this);

this.Items = new BindableCollection<ItemViewModel>();

}

// the items displayed on the canvas

public BindableCollection<ItemViewModel> Items { get; set; }

// adds an item to the collection

public void AddItem()

{

this.Items.Add(new ItemViewModel(this.events));

}

// fired when an item has been moved

public void Handle(ItemMovedEvent message)

{

// TODO: handle snapping to other elements

}

Then the view (I’m removing things like styling for brevity). Note that it follows Caliburn.Micro conventions on naming (among other things), so it automatically binds some things, like the ItemsControl items through its name.

<UserControl xmlns:cal="http://www.caliburnproject.org"
             xmlns:behaviors="clr-namespace:DragSnap.Behaviors">
    <Grid>
        <Button
            Content="Add an item to the canvas"
            cal:Message.Attach="[Event Click] = [Action AddItem()]" />

        <ItemsControl x:Name="Items">
            <ItemsControl.ItemsPanel>
                <ItemsPanelTemplate>
                    <Canvas />
                </ItemsPanelTemplate>
            </ItemsControl.ItemsPanel>
            <ItemsControl.ItemContainerStyle>
                <!-- This is what actually moves the items in the canvas -->
                <Style TargetType="ContentPresenter">
                    <Setter Property="Canvas.Left" Value="{Binding Path=X}" />
                    <Setter Property="Canvas.Top" Value="{Binding Path=Y}" />
                    <Setter Property="Width" Value="{Binding Path=Width}" />
                    <Setter Property="Height" Value="{Binding Path=Height}" />
                </Style>
            </ItemsControl.ItemContainerStyle>
            <ItemsControl.ItemTemplate>
                <DataTemplate>
                    <!-- The {Binding} binds the property's value to the ViewModel itself -->
                    <Border behaviors:DragOnCanvasBehavior.DropHandler="{Binding}">
                        <!-- Whatever content you want -->
                    </Border>
                </DataTemplate>
            </ItemsControl.ItemTemplate>
        </ItemsControl>
    </Grid>
</UserControl>

<UserControl xmlns:cal="http://www.caliburnproject.org"

xmlns:behaviors="clr-namespace:DragSnap.Behaviors">

<Grid>

<Button

Content="Add an item to the canvas"

cal:Message.Attach="[Event Click] = [Action AddItem()]" />

<ItemsControl.ItemsPanel>

</ItemsPanelTemplate>

</ItemsControl.ItemsPanel>

<ItemsControl.ItemContainerStyle>

</Style>

</ItemsControl.ItemContainerStyle>

<ItemsControl.ItemTemplate>

</Border>

</DataTemplate>

</ItemsControl.ItemTemplate>

</ItemsControl>

</Grid>

</UserControl>

To summarize:

The behavior is attached to the item’s viewmodel from the view
The behavior memorizes the item instance through the IDragDropHandler interface, and assigns mouse events to the item
The mouse events call the IDragDropHandler methods
The item’s viewmodel implements these methods and handles coordinates changes itself (which are visually updated through binding in the view)
The item viewmodel notifies the container viewmodel of its coordinates changes through Caliburn.Micro events

Unit testing custom querystring-based authorization on a WebApi controller

I needed to add a very simple authorization mechanism to my API: use a query string parameter “api_key”, so that it’s compatible with Swagger (using Swashbuckle, there is a field “api_key” in the Swagger UI) and is easily callable through Ruby On Rails.

Following and adapting a nice tutorial, I have done the following.

Implement the authorization filter

Create an interface for your API key “getter”:

public interface IApiKeyProvider
{
    string GetApiKey();
}

public interface IApiKeyProvider

{

string GetApiKey();

}

Implement this interface; here it’s extremely simple:

public class WebConfigApiKeyProvider : IApiKeyProvider
{
    public string GetApiKey()
    {
        return ConfigurationManager.AppSettings["api_key"];
    }
}

public class WebConfigApiKeyProvider : IApiKeyProvider

{

public string GetApiKey()

{

return ConfigurationManager.AppSettings["api_key"];

}

Inject this interface through your dependency injector of choice. You don’t have to modify your controllers, which is great.

Then create a filter attribute to use this implementation:

public class ApiKeyAuthorizeAttribute : ActionFilterAttribute
{
    private const string apiKeyParamName = "api_key";

    public override void OnActionExecuting(HttpActionContext filterContext)
    {
        // get the IApiKeyProvider instance that has been injected (oh MVC4 that provides a dependency resolver, I love you)
        var provider = filterContext.ControllerContext.Configuration.DependencyResolver.GetService(typeof(IApiKeyProvider)) as IApiKeyProvider;
        // get the query string parameter ;
        // it must be parsed from the full query, since it's not actually part of the action, but an additional parameter
        var queryStringCollection = HttpUtility.ParseQueryString(filterContext.Request.RequestUri.Query);
        string apiKey = queryStringCollection[apiKeyParamName];

        if (string.IsNullOrEmpty(apiKey) || apiKey != provider.GetApiKey())
        {
            throw new HttpResponseException(HttpStatusCode.Unauthorized);
        }

        base.OnActionExecuting(filterContext);
    }
}

public class ApiKeyAuthorizeAttribute : ActionFilterAttribute

{

private const string apiKeyParamName = "api_key";

public override void OnActionExecuting(HttpActionContext filterContext)

{

// get the IApiKeyProvider instance that has been injected (oh MVC4 that provides a dependency resolver, I love you)

var provider = filterContext.ControllerContext.Configuration.DependencyResolver.GetService(typeof(IApiKeyProvider)) as IApiKeyProvider;

// get the query string parameter ;

// it must be parsed from the full query, since it's not actually part of the action, but an additional parameter

var queryStringCollection = HttpUtility.ParseQueryString(filterContext.Request.RequestUri.Query);

string apiKey = queryStringCollection[apiKeyParamName];

if (string.IsNullOrEmpty(apiKey) || apiKey != provider.GetApiKey())

{

throw new HttpResponseException(HttpStatusCode.Unauthorized);

}

base.OnActionExecuting(filterContext);

}

Now you just have to add the [ApiKeyAuthorize] attribute to your controller(s), and you now need to add the proper api_key query string parameter to all your requests.

Test the filter

A few things to test: that your class uses this attribute, and that the attribute does what it says it does.

Test the attribute presence

Here I’m using XUnit and FluentAssertions.
It’s just a matter of listing the attributes on the class, and checking that an attribute matching the one created exists.

[Fact]
public void Archives_controller_has_attribute()
{
    var attributes = typeof(ArchivesController).GetCustomAttributes(true);
    attributes.Count().Should().BeGreaterThan(0, "because there should be at least an attribute");
    var attribute = attributes.OfType<ApiKeyAuthorizeAttribute>().Single();
    attribute.Should().NotBeNull("because there should be an IApiKeyProvider on the archives controller");
}

[Fact]

public void Archives_controller_has_attribute()

{

var attributes = typeof(ArchivesController).GetCustomAttributes(true);

attributes.Count().Should().BeGreaterThan(0, "because there should be at least an attribute");

var attribute = attributes.OfType<ApiKeyAuthorizeAttribute>().Single();

attribute.Should().NotBeNull("because there should be an IApiKeyProvider on the archives controller");

}

Test the attribute inner workings

What are we testing there? That the attribute throws a HttpResponseException when no parameter exists or when the value is wrong, and that it doesn’t throw an exception when it matches.

Setup the tests

Using XUnit and Moq, the test setup looks like this:

private ApiKeyAuthorizeAttribute attribute = new ApiKeyAuthorizeAttribute();
private HttpActionContext context = ContextUtil.CreateActionContext();
private Mock<IStorageModel> storageModelMock = new Mock<IStorageModel>();
private Mock<IApiKeyProvider> apiKeyProviderMock = new Mock<IApiKeyProvider>();

public ApiKeyAuthorizeAttributeTests()
{
    apiKeyProviderMock.Setup(p => p.GetApiKey()).Returns("abc");
    storageModelMock.Setup(s => s.CreationArchived(It.IsAny<string>())).Returns(true);
    storageModelMock.Setup(s => s.CreationArchives(It.IsAny<string>())).Returns(new List<Archive>());
    storageModelMock.Setup(s => s.ListArchives(It.IsAny<int>(), It.IsAny<int>())).Returns(new List<Archive>());
    InjectionSetup.Register(context.ControllerContext.Configuration, storageModelMock.Object, apiKeyProviderMock.Object);
}

private ApiKeyAuthorizeAttribute attribute = new ApiKeyAuthorizeAttribute();

private HttpActionContext context = ContextUtil.CreateActionContext();

private Mock<IStorageModel> storageModelMock = new Mock<IStorageModel>();

private Mock<IApiKeyProvider> apiKeyProviderMock = new Mock<IApiKeyProvider>();

public ApiKeyAuthorizeAttributeTests()

{

apiKeyProviderMock.Setup(p => p.GetApiKey()).Returns("abc");

storageModelMock.Setup(s => s.CreationArchived(It.IsAny<string>())).Returns(true);

storageModelMock.Setup(s => s.CreationArchives(It.IsAny<string>())).Returns(new List<Archive>());

storageModelMock.Setup(s => s.ListArchives(It.IsAny<int>(), It.IsAny<int>())).Returns(new List<Archive>());

InjectionSetup.Register(context.ControllerContext.Configuration, storageModelMock.Object, apiKeyProviderMock.Object);

}

The ContextUtil.CreateActionContext method can be picked from the ASP.Net source. The corresponding tests can be found here.

My InjectionSetup.Register is a unit-test-specific injection that allows to use a specific instance instead of creating one, here using LightInject:

public static void Register(HttpConfiguration config, IStorageModel storageModel, IApiKeyProvider apiKeyProvider)
{
    var container = new ServiceContainer();
    container.Register<IStorageModel>((factory) => storageModel);
    container.Register<IApiKeyProvider>((factory) => apiKeyProvider);
    container.RegisterApiControllers();
    container.EnableWebApi(config);
}

public static void Register(HttpConfiguration config, IStorageModel storageModel, IApiKeyProvider apiKeyProvider)

{

var container = new ServiceContainer();

container.Register<IStorageModel>((factory) => storageModel);

container.Register<IApiKeyProvider>((factory) => apiKeyProvider);

container.RegisterApiControllers();

container.EnableWebApi(config);

}

Test the attribute

Still using XUnit and FluentAssertions, three simple tests allow to check that the responses are what is expected:

[Fact]
public void Missing_key_throws_error()
{
    context.Request.RequestUri = new Uri("http://localhost/api/archives");
    Action act = () => attribute.OnActionExecuting(context);
    act.ShouldThrow<HttpResponseException>("because a non-authorized action should throw an exception").And.Response.StatusCode.Should().Be(HttpStatusCode.Unauthorized, "because the request should not be authorized");
}

[Fact]
public void Wrong_key_throws_error()
{
    context.Request.RequestUri = new Uri("http://localhost/api/archives?api_key=wrong");
    Action act = () => attribute.OnActionExecuting(context);
    act.ShouldThrow<HttpResponseException>("because a wrong API key should throw an exception").And.Response.StatusCode.Should().Be(HttpStatusCode.Unauthorized, "because the request should not be authorized");
}

[Fact]
public void Right_key_passes()
{
    context.Request.RequestUri = new Uri("http://localhost/api/archives?api_key=abc");
    Action act = () => attribute.OnActionExecuting(context);
    act.ShouldNotThrow<HttpResponseException>("because an authorized action should not throw an exception");
}

[Fact]

public void Missing_key_throws_error()

{

context.Request.RequestUri = new Uri("http://localhost/api/archives");

Action act = () => attribute.OnActionExecuting(context);

act.ShouldThrow<HttpResponseException>("because a non-authorized action should throw an exception").And.Response.StatusCode.Should().Be(HttpStatusCode.Unauthorized, "because the request should not be authorized");

}

[Fact]

public void Wrong_key_throws_error()

{

context.Request.RequestUri = new Uri("http://localhost/api/archives?api_key=wrong");

Action act = () => attribute.OnActionExecuting(context);

act.ShouldThrow<HttpResponseException>("because a wrong API key should throw an exception").And.Response.StatusCode.Should().Be(HttpStatusCode.Unauthorized, "because the request should not be authorized");

}

[Fact]

public void Right_key_passes()

{

context.Request.RequestUri = new Uri("http://localhost/api/archives?api_key=abc");

Action act = () => attribute.OnActionExecuting(context);

act.ShouldNotThrow<HttpResponseException>("because an authorized action should not throw an exception");

}

Testing Entity Framework layer in database-first mode

In your app, you may have a “query” layer, where all your Linq queries are regrouped. If you don’t, you should. Having your queries inside your controller leads to poor testing and strong coupling.

You will want to test that your queries return what they say they return. In order to do that, you need to mock your Entity Framework entities container.

There is an awesome and complete tutorial here, explaining everything.

If you’re stuck on Visual Studio 2010, you will need to do a few things: first, download and install the ADO.NET DbContext Generator code template, so that your entities use the DbSet type. Then, open your Entity Framework container, right click inside and select “Add a code generation element” (or something like that, my VS is not in english) and select the DbContext elements you just downloaded. You will then be able to customize the way your entities are generated (awesome tool).

In all Visual Studio versions, if you’re not using code-first like the tutorial, you will have to modify the template generation to mark your entities list as virtual (so that they can be mocked). Open your xxx.Context.tt file, find the line with DbSet<<#=Code.Escape(entitySet.ElementType)#>> and add virtual in front of it. Now you can check out the generated xxx.Context.cs file to be sure it’s not doing crazy things.

While you’re at it, since you’re modifying the code templates, follow these awesome instructions to xml-document your generated entities.

Now, following the MSDN article, in your query tests (the ones returning a set of data), you will have to manually create the data to return, and “bind” it to the mock instance. Since you will have to do that in each of your query tests, don’t forget to extract it to a method:

/// <summary>
/// Sets up the mock set of entities to be used in tests
/// </summary>
/// <typeparam name="T">The type of the entities</typeparam>
/// <param name="mockSet">The mock set of entities to configure</param>
/// <param name="data">The data to use</param>
private void SetupMockEntities<T>(Mock mockSet, IQueryable<T> data)
{
    mockSet.As<IQueryable<T>>().Setup(m => m.Provider).Returns(data.Provider);
    mockSet.As<IQueryable<T>>().Setup(m => m.Expression).Returns(data.Expression);
    mockSet.As<IQueryable<T>>().Setup(m => m.ElementType).Returns(data.ElementType);
    mockSet.As<IQueryable<T>>().Setup(m => m.GetEnumerator()).Returns(data.GetEnumerator());
}

/// <summary>

/// Sets up the mock set of entities to be used in tests

/// </summary>

/// <typeparam name="T">The type of the entities</typeparam>

/// <param name="mockSet">The mock set of entities to configure</param>

/// <param name="data">The data to use</param>

private void SetupMockEntities<T>(Mock mockSet, IQueryable<T> data)

{

mockSet.As<IQueryable<T>>().Setup(m => m.Provider).Returns(data.Provider);

mockSet.As<IQueryable<T>>().Setup(m => m.Expression).Returns(data.Expression);

mockSet.As<IQueryable<T>>().Setup(m => m.ElementType).Returns(data.ElementType);

mockSet.As<IQueryable<T>>().Setup(m => m.GetEnumerator()).Returns(data.GetEnumerator());

}

Faking objects with FakeItEasy

Remember that time (yesterday) when I created my own fake implementations for my tests? Man, was I crazy.

There is an awesome library called FakeItEasy, which ease up your fake implementations.

Now, instead of implementing your own IEntitiesContainer (or whatever your data layer injection interface is), you can tell FakeItEasy to generate a new fake of this interface, and you get a bunch of assertion methods on it thrown in for good measure.

private readonly OrdersController controller;

private readonly IEntitiesContainer fakeContainer;

public CommandesControllerTests()
{
    // use a fake of the interface to inject in the controller
    this.fakeContainer = A.Fake<IEntitiesContainer>();
    this.controller = new OrdersController(this.fakeContainer);
}

[Fact]
public void Controller_gets_single_item()
{
    // arrange: the GetOrder method with whatever parameter will return something
    A.CallTo(() => this.fakeContainer.GetOrder(A<int>.Ignored)).Returns(new OrderDto());

    // act
    OrderDto result = this.controller.GetOrders(0);

    // assert: make sure the underlying IEntitiesContainer's proper method has been called
    result.Should().NotBeNull("because the method should fetch an item");
    A.CallTo(() => this.fakeContainer.GetOrder(A<int>.Ignored)).MustHaveHappened();
}

private readonly OrdersController controller;

private readonly IEntitiesContainer fakeContainer;

public CommandesControllerTests()

{

// use a fake of the interface to inject in the controller

this.fakeContainer = A.Fake<IEntitiesContainer>();

this.controller = new OrdersController(this.fakeContainer);

}

[Fact]

public void Controller_gets_single_item()

{

// arrange: the GetOrder method with whatever parameter will return something

A.CallTo(() => this.fakeContainer.GetOrder(A<int>.Ignored)).Returns(new OrderDto());

// act

OrderDto result = this.controller.GetOrders(0);

// assert: make sure the underlying IEntitiesContainer's proper method has been called

result.Should().NotBeNull("because the method should fetch an item");

A.CallTo(() => this.fakeContainer.GetOrder(A<int>.Ignored)).MustHaveHappened();

}

It also helps you make sure you’re testing the right things. For instance, I had a test method return a list of paginated result, and went to great lengths to make sure the proper number of items were returned. After spending a bit of time trying to refactor my test (because FakeItEasy doesn’t make it easy to provide specific parameters), I found out I don’t care about the number of returned results, since this is tested elsewhere.

Creating a web API using ASP.Net WebApi over a legacy database

I’m trying to create a coherent API to access a crazy legacy database, do I decided to use an Asp.Net WebApi project. Since I want to get a somewhat sane result, I’ll test everything.

First things first: create a new WebApi project. It’s a type of project, located under Asp.Net MVC websites.
Don’t forget to update the project’s nuget packages ASAP, since doing it too late will make you tear you hairs out with broken links and missing files.

I will not go over creating API controllers, models etc, because there are a billion websites to help you with that, and it’s pretty straightforward. Instead, I will try to regroup all “best practices” when dealing with a web API in a single place, applied to the problems of dealing with a legacy database. I will also not dwell on the various concepts (data transfer objects, dependency injection, etc), you can read more about them at length with a quick Google search.

Version your API

If your project has any kind of risk associated with it (which means: once in production, will breaking it make you lose money?), you should version your API. So that your website can use the latest and most awesome version, but an executable running somewhere lost and forgotten in the bowels of your middle office doesn’t suddenly (and probably silently) crash once a method returns differently-named fields.

For that, there are several method, each one with various cons and pros. You can read a nice summary (and how to include all main methods at once in your project) here.
I decided to use URL versioning, because it’s the most simple to use and understand, and the most “visible”. Working with various contractors that use various languages and technologies, I always have to choose the less painful option.

To implement API URL-based versioning, the most simple, painless option is to use attribute-based routing. Make sure you have the AttributeRouting.WebApi Nuget package, and just add attributes to your controller’s methods:

[GET("api/v1/orders/{id}")]
public OrderDto GetOrder(int id) {}

1 2	[GET("api/v1/orders/{id}")] public OrderDto GetOrder(int id) {}

I advise you against using namespace-based versioning (as seen here), because it makes your life a living nightmare. Everything you will be using (like Swagger) will assume your API is not versioned, so you have to keep default routes, and namespace-based versioning doesn’t allow that (unless you succeed in modifying the linked class, which I didn’t try).

Create a public data layer

Publish Data Transfer Objects (DTO)

One annoying thing when you try to “publish” entities from Entity Framework, is that you get all the foreign keys relationship stuff in your JSON result.
It also strongly links your underlying model with your API, which may be OK, but is not awesome, especially considering that our model is crazy (still working with a legacy DB, remember?).

So, in order to solve these problems (and also because I am not fond of publishing the underlying data model directly), there is a design pattern called Data Transfer Objects.

To implement this pattern, let’s create a Model project, create the Entity Framework entities inside, and publish them through custom and “clean” objects.

Always be remembering that we’re dealing with a legacy DB. Our crazy fields with random casing, cryptic names and insane types (for instance, everything in my main table is a varchar 100, even dates, booleans and numbers) would really love a nice grooming. You’re in luck, because tools exist to make your life easier.

We will use AutoMapper to bind the entities to the custom data objects. This awesome tool will do much of the grunt work for us.

Let’s pretend that in the actual DB, we have entities looking a bit like this:

class Order {
  string emailid { get; set; }
  string Item_quantity { get; set; }
  string Shipping_Date { get; set; }
}

class Order {

string emailid { get; set; }

string Item_quantity { get; set; }

string Shipping_Date { get; set; }

}

Since having all fields as string and with random casing is clearly insane (or lazy, or both, who knows?), we want to map it to an object like this:

class OrderDto {
  string Email { get; set; }
  int ItemQuantity { get; set; }
  DateTime? ShippingDate { get; set; }
}

class OrderDto {

string Email { get; set; }

int ItemQuantity { get; set; }

DateTime? ShippingDate { get; set; }

}

In order to do that, we will use AutoMapper so that we don’t have to manually create object converters. It doesn’t prevent us to write code, though, it just means that all mapping code can be stored in a single place.

public class AutoMapperBoostrapper
{
    public static void Map()
    {
        // system types conversions
        Mapper.CreateMap<string, int>().ConvertUsing((v) => { return Convert.ToInt32(v); });
        Mapper.CreateMap<string, DateTime?>().ConvertUsing<DateTimeNullConverter>();

        // Orders: entities => DTO
        Mapper.CreateMap<Order, OrderDto>()
              .ForMember(dest => dest.Email, opt => opt.MapFrom(src => src.emailid))
              .ForMember(dest => dest.ItemQuantity, opt => opt.MapFrom(src => src.Item_quantity))
              .ForMember(dest => dest.ShippingDate, opt => opt.MapFrom(src => src.Shipping_Date));
    }
}

public class AutoMapperBoostrapper

{

public static void Map()

{

// system types conversions

Mapper.CreateMap<string, int>().ConvertUsing((v) => { return Convert.ToInt32(v); });

Mapper.CreateMap<string, DateTime?>().ConvertUsing<DateTimeNullConverter>();

// Orders: entities => DTO

Mapper.CreateMap<Order, OrderDto>()

.ForMember(dest => dest.Email, opt => opt.MapFrom(src => src.emailid))

.ForMember(dest => dest.ItemQuantity, opt => opt.MapFrom(src => src.Item_quantity))

.ForMember(dest => dest.ShippingDate, opt => opt.MapFrom(src => src.Shipping_Date));

}

System types are best converted using system conversion, but in my case the datetime have some weird things going on, so I created my own converter.

Note that you can also write a custom converter to convert from and to Order and OrderDto. However, it makes you write mapping method “by hand” in various places like constructors, and I like having all the casting in one place, even though it can get quite long after a while. The mapping can also be much more complicated than the above example, as seen here for instance, and using AutoMapper helps a lot in these cases.

Use dependency injection to publish the DTOs

In order to help in the next step (creating test), we will use dependency injection in our controllers.

In your Model project, create a IEntitiesContainer interface with all the methods to fetch the data you need.

public interface IEntitiesContainer : IDisposable
{
    void AddOrder(OrderDto order);
    void EditOrder(OrderDto order);
    OrderDto GetOrders(int id);
    IEnumerable<OrderDto> GetPaginatedOrders(int page, int pageSize);
}

public interface IEntitiesContainer : IDisposable

{

void AddOrder(OrderDto order);

void EditOrder(OrderDto order);

OrderDto GetOrders(int id);

IEnumerable<OrderDto> GetPaginatedOrders(int page, int pageSize);

}

Then, still in your Model project, implement this interface in a class that will wrap around the actual Entity Framework container.

Note that tying the controller to the MyEntities() implementation is not the best approach, but solving it is well documented.

public class MyEntitiesContainer : IEntitiesContainer
{
    private readonly DB.MyEntities db;

    public MyEntitiesContainer()
    {
        this.db = new MyEntities();
    }

    public void AddOrder(OrderDto order)
    {
        this.db.Orders.AddObject(Mapper.Map<Order>(order));
        this.db.SaveChanges();
    }

    public void Dispose()
    {
        this.db.Dispose();
    }

    public void EditOrder(OrderDto order)
    {
        Order existing = this.db.Orders.Where(o => o.id == order.id).Single();
        existing = Mapper.Map<OrderDto, Order>(order, existing);
        this.db.ObjectStateManager.ChangeObjectState(existing, System.Data.EntityState.Modified);
        this.db.SaveChanges();
    }

    public OrderDto GetOrder(int id)
    {
        return Mapper.Map<OrderDto>(this.db.Orders.Where(o => o.id == id).FirstOrDefault());
    }

    public IEnumerable<OrderDto> GetPaginatedOrders(int page, int pageSize)
    {
        return Mapper.Map<IEnumerable<OrderDto>>(
            this.db.Orders.OrderByDescending(o => o.id).Paginate(page, pageSize).AsEnumerable());
    }
}

public class MyEntitiesContainer : IEntitiesContainer

{

private readonly DB.MyEntities db;

public MyEntitiesContainer()

{

this.db = new MyEntities();

}

public void AddOrder(OrderDto order)

{

this.db.Orders.AddObject(Mapper.Map<Order>(order));

this.db.SaveChanges();

}

public void Dispose()

{

this.db.Dispose();

}

public void EditOrder(OrderDto order)

{

Order existing = this.db.Orders.Where(o => o.id == order.id).Single();

existing = Mapper.Map<OrderDto, Order>(order, existing);

this.db.ObjectStateManager.ChangeObjectState(existing, System.Data.EntityState.Modified);

this.db.SaveChanges();

}

public OrderDto GetOrder(int id)

{

return Mapper.Map<OrderDto>(this.db.Orders.Where(o => o.id == id).FirstOrDefault());

}

public IEnumerable<OrderDto> GetPaginatedOrders(int page, int pageSize)

{

return Mapper.Map<IEnumerable<OrderDto>>(

this.db.Orders.OrderByDescending(o => o.id).Paginate(page, pageSize).AsEnumerable());

}

Note that we’re not using AutoMapper’s Project().To(), because it doesn’t work great with Entity Framework when using type conversion.

Now use this new layer in your controller:

public class OrdersController : ApiController
{
    private readonly IEntitiesContainer db;

    public OrdersController()
    {
        this.db = new MyEntitiesContainer();
    }

    public OrdersController(IEntitiesContainer container)
    {
        this.db = container;
    }

    // your controller's actions
}

public class OrdersController : ApiController

{

private readonly IEntitiesContainer db;

public OrdersController()

{

this.db = new MyEntitiesContainer();

}

public OrdersController(IEntitiesContainer container)

{

this.db = container;

}

// your controller's actions

}

Now we can use the controller with any implementation of IEntitiesContainer in our tests.

Test the controller

Now that we have a foundation for the project, we can finally do some yummy tests. I will use xUnit (because it’s a great tool) and FluentAssertions (because it makes tests easier to read and write).

I will not go over testing the model, since it’s pretty well documented. However, testing the WebApi controller requires a bit more work.

In order to not hit the actual DB, we’ll use the dependency injection we’ve set up. Create an implementation of the IEntitiesContainer in your test project. I suggest using an awesome method that I found on a blog: create a mostly-empty implementation, for which you will provide the implementation on a case-by-case basis.

internal class FakeEntitiesContainer : IEntitiesContainer
{
    public Action<Commandes> AddCommande { get; set; }
    public Func<int, Commandes> GetCommande { get; set; }

    void IEntitiesContainer.AddCommande(Commandes commandes)
    {
        if (this.AddCommande != null)
        {
            this.AddCommande(commandes);
        }
        else
        {
            throw new NotImplementedException();
        }
    }

    Commandes IEntitiesContainer.GetCommande(int id)
    {
        if (this.GetCommande != null)
        {
            return this.GetCommande(id);
        }
        else
        {
            throw new NotImplementedException();
        }
    }
}

internal class FakeEntitiesContainer : IEntitiesContainer

{

public Action<Commandes> AddCommande { get; set; }

public Func<int, Commandes> GetCommande { get; set; }

void IEntitiesContainer.AddCommande(Commandes commandes)

{

if (this.AddCommande != null)

{

this.AddCommande(commandes);

}

else

{

throw new NotImplementedException();

}

Commandes IEntitiesContainer.GetCommande(int id)

{

if (this.GetCommande != null)

{

return this.GetCommande(id);

}

else

{

throw new NotImplementedException();

}

Then your controller test can use this fake like this:

public class OrdersControllerTests : IDisposable
{
    private readonly OrdersController controller;
    private readonly FakeEntitiesContainer fakeContainer;

    public CommandesControllerTests()
    {
        this.fakeContainer = new FakeEntitiesContainer();
        this.controller = new OrdersController(this.fakeContainer);
    }

    [Fact]
    public void Controller_gets_single_item()
    {
        // arrange
        OrderDto item = new OrderDto() { id = 123 };
        this.fakeContainer.GetOrder = (id) =>
            {
                if (id == item.id)
                {
                    return item;
                }

                return null;
            };
        TestsBoostrappers.SetupControllerForTests(this.controller, "orders", HttpMethod.Get);

        // act
        OrderDto result = this.controller.GetOrders(item.id);

        // assert
        result.ShouldBeEquivalentTo(item, "because the method should fetch the correct item");

        // cleanup
        this.fakeContainer.GetOrder = null;
    }

}

public class OrdersControllerTests : IDisposable

{

private readonly OrdersController controller;

private readonly FakeEntitiesContainer fakeContainer;

public CommandesControllerTests()

{

this.fakeContainer = new FakeEntitiesContainer();

this.controller = new OrdersController(this.fakeContainer);

}

[Fact]

public void Controller_gets_single_item()

{

// arrange

OrderDto item = new OrderDto() { id = 123 };

this.fakeContainer.GetOrder = (id) =>

{

if (id == item.id)

{

return item;

}

return null;

};

TestsBoostrappers.SetupControllerForTests(this.controller, "orders", HttpMethod.Get);

// act

OrderDto result = this.controller.GetOrders(item.id);

// assert

result.ShouldBeEquivalentTo(item, "because the method should fetch the correct item");

// cleanup

this.fakeContainer.GetOrder = null;

}

The TestsBoostrappers.SetupControllerForTests() method configures the routes of the controller. If we don’t do that, the controller won’t know what to do.

internal class TestsBoostrappers
{
    public static HttpRequestMessage NewHttpMessage(HttpMethod method, string controllerName)
    {
        return new HttpRequestMessage(method, string.Format("http://localhost/api/v1/{0}", controllerName));
    }
    
    public static void SetupControllerForTests(ApiController controller, string controllerName, HttpMethod method)
    {
        var request = NewHttpMessage(method, controllerName);
        var config = new HttpConfiguration();
        var route = WebApiConfig.Register(config).First();
        var routeData = new HttpRouteData(route, new HttpRouteValueDictionary
                                                 {
                                                     {
                                                             "controller",
                                                             controllerName
                                                     }
                                                 });

        controller.ControllerContext = new HttpControllerContext(config, routeData, request);
        controller.Request = request;
        controller.Request.Properties[HttpPropertyKeys.HttpConfigurationKey] = config;
        controller.Request.Properties[HttpPropertyKeys.HttpRouteDataKey] = routeData;
    }
}

internal class TestsBoostrappers

{

public static HttpRequestMessage NewHttpMessage(HttpMethod method, string controllerName)

{

return new HttpRequestMessage(method, string.Format("http://localhost/api/v1/{0}", controllerName));

}

public static void SetupControllerForTests(ApiController controller, string controllerName, HttpMethod method)

{

var request = NewHttpMessage(method, controllerName);

var config = new HttpConfiguration();

var route = WebApiConfig.Register(config).First();

var routeData = new HttpRouteData(route, new HttpRouteValueDictionary

{

"controller",

controllerName

}

});

controller.ControllerContext = new HttpControllerContext(config, routeData, request);

controller.Request = request;

controller.Request.Properties[HttpPropertyKeys.HttpConfigurationKey] = config;

controller.Request.Properties[HttpPropertyKeys.HttpRouteDataKey] = routeData;

}

One last, but very important, point of interest on your tests. In order to follow the REST principles, after certain actions, your API should return some specific data. For instance, after an item creation, it should return the URL to this new item. Your POST method may look like this:

public HttpResponseMessage PostOrders(OrderDto order)
{
    if (this.ModelState.IsValid)
    {
        this.db.AddOrder(order);

        HttpResponseMessage response = this.Request.CreateResponse(HttpStatusCode.Created, order);

        string link = this.Url.Link(
            "DefaultApi",
            new
            {
                id = order.id
            });
        var uri = new Uri(link);
        response.Headers.Location = uri;

        return response;
    }
    else
    {
        return this.Request.CreateResponse(HttpStatusCode.BadRequest);
    }
}

public HttpResponseMessage PostOrders(OrderDto order)

{

if (this.ModelState.IsValid)

{

this.db.AddOrder(order);

HttpResponseMessage response = this.Request.CreateResponse(HttpStatusCode.Created, order);

string link = this.Url.Link(

"DefaultApi",

new

{

id = order.id

});

var uri = new Uri(link);

response.Headers.Location = uri;

return response;

}

else

{

return this.Request.CreateResponse(HttpStatusCode.BadRequest);

}

This simple this.Url creates an URL based on your routes and such, but if you’re using WebApi 1 like me (because you’re stuck on .Net 4.0 in Visual Studio 2010), all documented solutions won’t work, and will make you want to flip your desktop. In order to solve that, I simply used another dependency injection to wrap the UrlHelper class, and provide my own implementations in my tests.

Document your API

Documenting your API is pretty easy using Swagger. An Nuget package wrapping the implementation for .Net is available as Swashbuckle. Add it to your API project, and then you can access the documentation through /swagger/.

Switching program from .Net 4.0 to 4.5

If, like me, you switched your .Net program from 4.0 to 4.5, you might have encountered a bunch of problems.

What worked for me is the following.

First, modify your projects to use .Net 4.5. Make sure it builds (even if you might get a bunch of errors). Save and commit.

Next, run the following command in the VS package manager console:

Update-Package –reinstall -ignoreDependencies

1	Update-Package –reinstall -ignoreDependencies

This should reinstall your Nuget packages without touching their dependencies.

If you still get MSB3277 errors (“Found conflicts between different versions of the same dependent assembly that could not be resolved”), follow these steps:

In Visual Studio, open tools > options > projects and solutions > build and run > select “detailed” for the two msbuild output options.
Build your project
In the “output” window, search for MSB3277. Go up a little bit, and look for “A conflict exists between…”. It will tell you which assembly is conflicted.

Myself, it was the System assembly… weird.

The both most simple, and most annoying solution, is to remove all references and Nuget packages, then add them back.

Using NUnit for a .Net 4 project in a Jenkins installation

I have migrated my MBUnit tests to NUnit, considering MBUnit has been “on hiatus” for about a year now. NUnit is not much more agile, but at least there is a semblance of life on their Github account.

The switch has been surprisingly easy: change the namespace, change TestRow with Test, and change Row with TestCase. Easy!

Run unit tests in your continuous integration platform

In order to integrate the tests in our continuous integration platform, while minimizing build time, I have split the setup package build and the unit tests run. So I have a job that runs at each commit, that builds the project and generates the setup packages; and another job running at midnight, that only builds the project and runs unit tests.

Apparently, using the automatic package restore from Visual Studio is now obsolete with the latest Nuget versions. So I followed the instructions and migrated to Nuget package restore. Remember to download nuget.exe from nuget.org, add it to the CI server’s PATH, and restart Jenkins.

Add the NUnit Nuget packages to the test projects, and remember to add the NUnit Runner Nuget package to the solution! It will be much easier to run the unit tests this way (no need to install NUnit on the CI server).

I’m using PSAke for my build process (awesome tool!), so now my script looks like this:

Properties {
  $ROOT_PATH = [System.IO.Path]::GetFullPath((Join-Path (pwd) ".\build"))
  $APP_PATH = Join-Path $ROOT_PATH "app"
  $TESTS_PATH = Join-Path $ROOT_PATH "tests"
  $NUNIT_PATH = Join-Path (pwd) "packages\NUnit.Runners.2.6.3\tools\nunit-console-x86.exe" # note that if you build your test binaries for x86, you must use the x86 test runner
}

Framework "4.0x86" # this builds using the 32-bit .Net 4

# This is the task that is run by the "standard" job
task default -depends Cleanup, Build, Config, Setup

# this is the task that is run by the "tests" job
task Test -depends Cleanup, BuildNUnit {
  Get-ChildItem $TESTS_PATH -Filter "*.*Test*.dll" | % {
    $result = (Join-Path $resultsPath $_.Name) -replace ".dll",".xml"
    Start-Process $NUNIT_PATH -ArgumentList "`"$($_.FullName)`" /framework:net-4.0 /nologo /result:`"$result`"" -Wait -NoNewWindow
  }
}

task Restore {
  & nuget restore
}

task Cleanup { 
  # remove all binaries - only useful for local run
}

task Build -depends Restore { 
  Exec {
    msbuild "mysolution.sln" /t:Build /p:Configuration=Release /p:Platform=x86
  }
}

task BuildNUnit -depends Restore { 
  Exec {
    msbuild "mysolution.sln" /t:Build /p:Configuration=NUnit /p:Platform=x86
  }
}

task Config { 
  # modify config values
}

task Setup {
  # run InnoSetup to generate setup packages
}

Properties {

$ROOT_PATH = [System.IO.Path]::GetFullPath((Join-Path (pwd) ".\build"))

$APP_PATH = Join-Path $ROOT_PATH "app"

$TESTS_PATH = Join-Path $ROOT_PATH "tests"

$NUNIT_PATH = Join-Path (pwd) "packages\NUnit.Runners.2.6.3\tools\nunit-console-x86.exe" # note that if you build your test binaries for x86, you must use the x86 test runner

}

Framework "4.0x86" # this builds using the 32-bit .Net 4

# This is the task that is run by the "standard" job

task default -depends Cleanup, Build, Config, Setup

# this is the task that is run by the "tests" job

task Test -depends Cleanup, BuildNUnit {

Get-ChildItem $TESTS_PATH -Filter "*.*Test*.dll" | % {

$result = (Join-Path $resultsPath $_.Name) -replace ".dll",".xml"

Start-Process $NUNIT_PATH -ArgumentList "`"$($_.FullName)`" /framework:net-4.0 /nologo /result:`"$result`"" -Wait -NoNewWindow

}

task Restore {

& nuget restore

}

task Cleanup {

# remove all binaries - only useful for local run

}

task Build -depends Restore {

Exec {

msbuild "mysolution.sln" /t:Build /p:Configuration=Release /p:Platform=x86

}

task BuildNUnit -depends Restore {

Exec {

msbuild "mysolution.sln" /t:Build /p:Configuration=NUnit /p:Platform=x86

}

task Config {

# modify config values

}

task Setup {

# run InnoSetup to generate setup packages

}

And now my Jenkins jobs consist of a simple batch line:

powershell "Import-Module .\psake.psm1 ; Invoke-Psake .\build.ps1 MYTASKNAME"

1	powershell "Import-Module .\psake.psm1 ; Invoke-Psake .\build.ps1 MYTASKNAME"

I have sumbled on a System.BadImageFormatException while running tests in Jenkins using nunit-console, or trying to add the assemblies to the NUnit GUI runner. Here are a few things to remember:

Do not use AnyCPU

Your test assemblies, assemblies linked by your tests, and really your whole project, should be built in 32-bits mode, so that they can be run by the 32-bits test runner. Personnaly, I created a “NUnit” solution configuration just for this. It allows me to select which assemblies are built in which case: no need to build tests in the general build, and no need to build stuff like bootstrapper exes in the test build.

Check your build paths

If you create a new configuration like I did, remember to change the build path! My main project builds in the \build\app folder, and my tests are located in \build\tests. I spent a few minutes wondering why the platform change did nothing, before finding out that my x86 test assemblies were in bin\x86\NUnit (the default value).

Check the framework version

Select the proper .Net framework with the /framework:net-4.0 switch. NUnit should be able to find out automagically, but sometimes it doesn’t.

WPF/SOAP configuration for third-party webservice with empty security headers

I am writing a program that accesses a SOAP webservice written by a third-party provider.

I need to provide a user and login in the SOAP headers, which is kind of easy, in theory:

add the webservice reference to Visual Studio
instantiate a new “XXXXClient” generated class
set xxx.ClientCredentials.UserName.UserName and xxx.ClientCredentials.UserName.Password

Easy as pie. Except when it’s not. You see, the provider’s webservice is written using php, it does not behave nicely with .Net. When you send the request, you can see on Fiddler that the query is sent and gets a response, but .Net does not like this response, and throws exceptions around.

First problem: it throws a MesssageSecurityException because of empty security headers in the response (see here). I first thought that I had the same problem, so I spent the day resolving the issue following this blog post, but it turns out it’s much more simple. To fix this, you must set the enableUnsecuredResponse in the binding’s security node to true. And in order to do that, your binding must be a customBinding. If you have a complicated binding, good luck switching.

Second problem: the mime type for the request and the response are different (“text/xml” vs “application/soap+xml”). To fix this one, you have to write your own custom text encoder (download the WCF examples at the top), and to do that… you have to create something like a thousand classes with a hundred lines each. Just for a simple mime type mismatch! Do not forget to also copy, from the downloadable examples, the BindingElement, BindingSection, ConfigurationStrings, and MessageVersionConverter !

So, for such a simple task, as is too often the case with Microsoft, I need to rewrite (or copy, here) a whole bunch of stuff, just to modify some pretty mundane and common behavior, which should be configurable in the first place. It shows how extensible WCF is, and how bloated the extending is.

Anyway, here is a working app.config. For the code of the custom text message encoding class, as I said, just copy the MS examples (and don’t forget to rename the types in the bindingElementExtensions).

<system.serviceModel>
    <extensions>
        <bindingElementExtensions>
            <add name="customTextMessageEncoding" type="MyClient.SOAP.CustomMessageBindingSection, MyClient" />
        </bindingElementExtensions>
    </extensions>
    <bindings>
        <customBinding>
            <binding name="ThirdPartyOrderBinding">
                <customTextMessageEncoding messageVersion="Soap11" mediaType="text/xml" />
                <security authenticationMode="UserNameOverTransport" enableUnsecuredResponse="true" />
                <httpsTransport />
            </binding>
        </customBinding>
    </bindings>
    <client>
        <endpoint address="https://www.myservice.com/services/ThirdPartyOrder.php"
            binding="customBinding" bindingConfiguration="ThirdPartyOrderBinding"
            contract="MyServiceWS.ThirdPartyOrderPortType" name="ThirdPartyOrderPort" />
    </client>
</system.serviceModel>

<system.serviceModel>

</bindingElementExtensions>

</extensions>

</binding>

</customBinding>

</bindings>

<endpoint address="https://www.myservice.com/services/ThirdPartyOrder.php"

binding="customBinding" bindingConfiguration="ThirdPartyOrderBinding"

contract="MyServiceWS.ThirdPartyOrderPortType" name="ThirdPartyOrderPort" />

</client>

</system.serviceModel>

Debug integrated WPF WebBrowser scripts using Visual Studio

Copied and modified from another blog for future reference.

Note that in order to debug the Javascript inside a WebBrowser control, you don’t need the source code of the application (neat!).

Open Internet Explorer, go to Settings, tab Advanced, and, in the “Navigation” section:
- Uncheck “disable script debugging” (both IE and Other)
- Uncheck “Display friendly HTTP messages”
- Check “Display a notification about every script error”
Open an instance of Visual Studio. Open the Tools menu, Attach to Process, and on the “Attach to” line, click “Select…”, and only check “Script”.
Run the program including the WPF BrowserControl
Attach the Visual Studio instance to its process.

Now, open the “Solution explorer” tab/toolbox. You will see every Javascript file loaded by the WPF WebBrowser control, and you can add breakpoints where you want.

Tested with IE 11 and Visual Studio 2010.

Creating a C++/CLI wrapper around a C library

So, following my previous post, I have decided that I might try C++/CLI after all, since the SWIG way goes nowhere except “down in flames”, and I really need to implement it.

Turns out that creating a C++/CLI wrapper around a fairly well-made C library is not that hard.

Considering the following .h file from the C library (which are the methods and structures to interface):

typedef struct {
	int left;
	int top;
	int right;
	int bottom;
} frame_t;

typedef struct {
	/* IN */
	int width;
	int height;

	/* OUT */
	frame_t view;
	frame_t dest;
} image_t;

typedef struct {
	int page_width;
	int page_height;
	int margin;
	int nb_run;
} parameters_t;

int pack(image_t *images, int nb_images, parameters_t params);

typedef struct {

int left;

int top;

int right;

int bottom;

} frame_t;

typedef struct {

/* IN */

int width;

int height;

/* OUT */

frame_t view;

frame_t dest;

} image_t;

typedef struct {

int page_width;

int page_height;

int margin;

int nb_run;

} parameters_t;

int pack(image_t *images, int nb_images, parameters_t params);

Add the .h and .c files to a new C++ CLR DLL project, then add a new cpp file, in which we will replicate all the C structures as classes.
We have to name our classes differently than the C structures, otherwise there will be conflicts, both with the compiler, and in our heads.

#include <windows.h>
#include <vcclr.h>
#include "../../packer/packer.h"
#using <System.dll>
#using <mscorlib.dll>

using namespace System;

namespace Packer {

    public ref class Frame {
    public:
        int Left, Top, Right, Bottom;

    internal:
        frame_t ToNative() {
            frame_t f;
            f.left = Left;
            f.top = Top;
            f.right = Right;
            f.bottom = Bottom;
            return f;
        }

        Frame() { }

        Frame(const frame_t &f) {
            Left = f.left;
            Top = f.top;
            Right = f.right;
            Bottom = f.bottom;
        }
    };

    public ref class Image {
    public:
        int Width, Height;
        Frame ^View, ^Dest;
        
        Image() {
            View = gcnew Frame();
            Dest = gcnew Frame();
        }

    internal:
        image_t ToNative() {
            image_t i;
            i.width = Width;
            i.height = Height;
            i.view = View->ToNative();
            i.dest = Dest->ToNative();
            return i;
        }
    };

    public ref class Parameters {
    public:
        int PageWidth, PageHeight, Margin, NbRun;

    internal:
        parameters_t ToNative() {
            parameters_t p;
            p.page_width = PageWidth;
            p.page_height = PageHeight;
            p.margin = Margin;
            p.nb_run = NbRun;
            return p;
        }
    };

    public ref class Packer {
    private:
        int _nb_images;
        image_t* nativeImages;
    public:
        Packer(int nb_images) {
            _nb_images = nb_images;
            nativeImages = new image_t[_nb_images];
        }
        ~Packer() {
            delete[] nativeImages;
        }
        int Pack(array< Image^ >^% images, Parameters^ params) {
            // create a native array of image_t to send to the C library
            for(int i = 0; i < _nb_images; i++) {
                nativeImages[i] = images[i]->ToNative();
            }
            
            // call the packing method
            int result = pack(nativeImages, _nb_images, params->ToNative());

            // re-loop on images to get the values from native images, and assign them to managed images
            for(int i = 0; i < _nb_images; i++) {
                images[i]->View = gcnew Frame(nativeImages[i].view);
                images[i]->Dest = gcnew Frame(nativeImages[i].dest);
            }

            return result;
        }
    };
}

100

101

#include <windows.h>

#include <vcclr.h>

#include "../../packer/packer.h"

#using <System.dll>

#using <mscorlib.dll>

using namespace System;

namespace Packer {

public ref class Frame {

public:

int Left, Top, Right, Bottom;

internal:

frame_t ToNative() {

frame_t f;

f.left = Left;

f.top = Top;

f.right = Right;

f.bottom = Bottom;

return f;

}

Frame() { }

Frame(const frame_t &f) {

Left = f.left;

Top = f.top;

Right = f.right;

Bottom = f.bottom;

}

};

public ref class Image {

public:

int Width, Height;

Frame ^View, ^Dest;

Image() {

View = gcnew Frame();

Dest = gcnew Frame();

}

internal:

image_t ToNative() {

image_t i;

i.width = Width;

i.height = Height;

i.view = View->ToNative();

i.dest = Dest->ToNative();

return i;

}

};

public ref class Parameters {

public:

int PageWidth, PageHeight, Margin, NbRun;

internal:

parameters_t ToNative() {

parameters_t p;

p.page_width = PageWidth;

p.page_height = PageHeight;

p.margin = Margin;

p.nb_run = NbRun;

return p;

}

};

public ref class Packer {

private:

int _nb_images;

image_t* nativeImages;

public:

Packer(int nb_images) {

_nb_images = nb_images;

nativeImages = new image_t[_nb_images];

}

~Packer() {

delete[] nativeImages;

}

int Pack(array< Image^ >^% images, Parameters^ params) {

// create a native array of image_t to send to the C library

for(int i = 0; i < _nb_images; i++) {

nativeImages[i] = images[i]->ToNative();

}

// call the packing method

int result = pack(nativeImages, _nb_images, params->ToNative());

// re-loop on images to get the values from native images, and assign them to managed images

for(int i = 0; i < _nb_images; i++) {

images[i]->View = gcnew Frame(nativeImages[i].view);

images[i]->Dest = gcnew Frame(nativeImages[i].dest);

}

return result;

}

};

}

The annoying thing when like me, you know pretty much nothing about C/C++, is that you never know where to specify pointers and stuff, and it’s mostly trial and error (it says it can’t build, let’s add a *… nope, a & ? Yes, that seems to work).

A few things to note:

Provide internal ToNative() methods on the structure wrappers to ease up marshalling from managed objects to native structures.
Also provide internal constructors taking a native structure as parameter, to ease up marshalling from native to managed.
The “^%” syntax (for the “images” parameter of the “Pack” method) builds to a “ref” in the .Net method signature. Otherwise the calling C# can’t get the values back.

As you can see, it’s not that difficult after all. I guess for an experienced C/C++ developer it would be even more simple.