如何正确模拟HttpContextBase，以便我的单元测试正常工作

Question

Given the following function:

public static void Write(HttpContextBase contextBase, IUnitOfWork unitOfWork, LogLevel level, string title, string message, params AdditionalProperty[] properties)
{
    // Some variables that are set for writing the logs.
    //      - client: When the HttpContext is null, 'N.A.' is used, otherwise the I.P. address of the requesting computer.
    //      - userIdentifier: When the HttpContext exists and a value is stored in the cookie, the value of the cookie, otherwise an empty guid.
    //      - requestIdentifier: When the context is existing and a request have been made on a controller, a unique value identifying this request, otherwise an empty guid.

    string client = (contextBase.ApplicationInstance == null || contextBase.ApplicationInstance.Context.CurrentHandler == null) ? "N.A." : HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
    string userIdentifier = (contextBase.ApplicationInstance != null && contextBase.ApplicationInstance.Context != null && contextBase.ApplicationInstance.Context.CurrentHandler != null && CookieManager.Exists("UserIdentifier")) ? CookieManager.Read("UserIdentifier", Guid.NewGuid().ToString().ToUpper()) : Guid.Empty.ToString();
    string requestIdentifier = (contextBase.ApplicationInstance != null && contextBase.ApplicationInstance.Context != null && contextBase.ApplicationInstance.Context.Cache != null && HttpContext.Current.Cache["RequestIdentifier"] != null) ? HttpContext.Current.Cache["RequestIdentifier"].ToString() : Guid.Empty.ToString();

    // Additional code for processing is done here.
}

I'm using a HttpContextBase and an interface for a Unit Of Work, since I know it's easier to unit test than.

Now I'm using Moq to using Mocking functionality in my unit test and I'm struggling with it.

Let's see the variable cliënt:

string client = (contextBase.ApplicationInstance == null || contextBase.ApplicationInstance.Context.CurrentHandler == null) ? "N.A." : HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];

I would like to know how to setup my Unit Test(s) by mocking the necessary objects.

Here's my current unit test:

var context = new Mock<HttpContextBase>();
var httpApplicationMock = new Mock<HttpApplication>();

httpApplicationMock.SetupGet(x => x.Context).Returns(context.Object); --> FAILS
context.SetupGet(c => c.ApplicationInstance).Returns(httpApplicationMock.Object);

The setup of the httpApplicationMock is failing because context.Object is not a valid parameter but I need to pass in a HttpContext.

Can someone give me a little, gentle push in the right direction?

Answer 1

This line fails because Context returns HttpContext type, not HttpContextBase .

httpApplicationMock.SetupGet(x => x.Context).Returns(context.Object);

Creating context as Mock<HttpContext> instance won't help either because it's a sealed class and Moq can't mock sealed classes.

You can hide implementation details concerning HttpContext behind an interface. Here's blog post that shows you an example: http://volaresystems.com/Blog/post/2010/08/19/Dont-mock-HttpContext

Answer 2

After some further tests I've realized what it wrong.

First of all, and quite important, I'm using MSTest. So the problem does not rely on repository being created in the constructor because for each test that is runt through MSTest, the constructor is executed. So that's eliminated.

After some further inspection, I've realised that, to retrieve the settings from the settingsrepository, I use a class which is instantiated as a Singleton, and that was the problem.

When I run my first file with unit test with a specified setting, all went fine since the setting still needed to be created.

But in my second file, I use another settings, but since the manager which is responsible for getting the settings is a Singleton, the new settings were not retrieved and instead the settings from the previous one were used.

That caused the issue.

Anyway, thanks to the persons who have tried to helped me out on this situation.