Vidar’s Musings

As a follow-up to my previous post ASP.NET 3.5: improving testability with System.Web.Abstractions, I would like to show how the same testability can be achieved without using any mock framework like Rhino.Mocks. The C# 3.0 featuires ‘object initializers’ and ‘automatic properties’ makes our code sufficiently non-verbose to make it easy and readable.

So, given the same examples as in my previous post, here is what the test code will look like:

Example #1: Testing a page codebehind file

[TestMethod]
public void ShouldSetNoCacheabilityOnDefaultPage()
{
    _Default page = new _Default();
    HttpCachePolicyMock httpCachePolicyMock = new HttpCachePolicyMock();
    page.SetCacheablityOfResponse(new HttpResponseStub
    {
        TheCache = httpCachePolicyMock
    });
    httpCachePolicyMock.ShouldHaveSetCacheabilityTo(HttpCacheability.NoCache);
}

class HttpResponseStub : HttpResponseBase { public override HttpCachePolicyBase Cache { get { return TheCache; } } public HttpCachePolicyBase TheCache { get; set; } }

class HttpCachePolicyMock : HttpCachePolicyBase { private HttpCacheability _cacheability; public override void SetCacheability(HttpCacheability cacheability) { _cacheability = cacheability; } public void ShouldHaveSetCacheabilityTo(HttpCacheability expectedCacheability) { Assert.AreEqual(expectedCacheability, _cacheability); } } I have created two helper classes, one with the suffix -Stub and one with the suffix -Mock. The convention here is that a stub is a type of class used to provide a context to the class under test. Mocks also do that, but additionally a mock can make expectation about what should happen to it during the test.

Example #2: Testing an HTTP handler

[TestMethod]
public void ShouldRedirectAuthenticatedUser()
{
    HttpServerUtilityMock httpServerUtilityMock = new HttpServerUtilityMock();
    HttpContextStub httpContextStub = new HttpContextStub
    {
        TheRequest = new HttpRequestStub { IsItAuthenticated = true },
        TheServer = httpServerUtilityMock
    };
    new RedirectAuthenticatedUsersHandler().TransferUserIfAuthenticated(httpContextStub);
    httpServerUtilityMock.ShouldHaveTransferredTo("/farfaraway");
}

class HttpContextStub : HttpContextBase { public override HttpRequestBase Request { get { return TheRequest; } } public override HttpServerUtilityBase Server { get { return TheServer; } } public HttpRequestBase TheRequest { get; set; } public HttpServerUtilityBase TheServer { get; set; } }

class HttpRequestStub : HttpRequestBase { public override bool IsAuthenticated { get { return IsItAuthenticated; } } public bool IsItAuthenticated { get; set; } }

class HttpServerUtilityMock : HttpServerUtilityBase { private string _path; public override void TransferRequest(string path) { _path = path; }

public void ShouldHaveTransferredTo(string expectedPath)
{
    Assert.AreEqual(expectedPath, _path);
}

}

This entry was posted on Thursday, May 28th, 2009 at 10:14 am and is filed under Microsoft technologies, Software development. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.