How to mock httpcontext in service - unit-testing

Question

How can the httpcontext in this service be mocked?
When I attempt to unit test this service it complains about the httpcontext being null.
What can be used in place of the httpcontext? I'm using webforms not mvc. I have seen multiple posts on faking the httpcontext class but not using webforms.
public class FileService : IFileService
{
public string GetEmployeePicLocation(Employee employee)
{
string AgentFilesDirectory = "~\\AgentFiles\\";
Image newImage = new Image();
DirectoryInfo diSubPath =
new DirectoryInfo(HttpContext.Current.Server
.MapPath(AgentFilesDirectory + employee.User_Name));
string localDIR = AgentFilesDirectory + employee.User_Name + "\\";
string defaultDIR = AgentFilesDirectory + "nopic\\nopic.jpg";
string strFile;
if (diSubPath.Exists)
{
FileInfo[] arrJPG = diSubPath.GetFiles("*.jpg");
FileInfo[] arrPNG = diSubPath.GetFiles("*.png");
if (!(arrJPG.Length == 0) || !(arrPNG.Length == 0))
{
foreach (FileInfo f in diSubPath.GetFiles("*.jpg"))
{
newImage.ImageUrl = localDIR + employee.PicFile;
}
foreach (FileInfo f in diSubPath.GetFiles("*.png"))
{
newImage.ImageUrl = localDIR + employee.PicFile;
}
}
else
{
newImage.ImageUrl = defaultDIR;
}
}
if (!(diSubPath.Exists))
{
newImage.ImageUrl = defaultDIR;
}
return newImage.ImageUrl.ToString();
}
}

Answer 1

Even though you're not doing MVC, HttpContextBase is defined in the System.Web assembly (or if you're using .Net 3.5, in System.Web.Abstractions) and so you can still using it. Change your class to take an instance of HttpContextBase, and you can create a mock and set it up as needed.
Your class would look like this:
public class FileService : IFileService
{
private HttpContextBase httpContext;
public FileService(HttpContextBase httpContext) {
this.httpContext = httpContext;
}
Then in your test:
var httpContextMock = new Mock<HttpContextBase>();
httpContextMock.Setup(x => x.SkipAuthorization).Returns(true);
var fileService = new FileService(httpContextMock.Object);
You'll need to also use some DI pattern so that the HttpContextBase instance is passed in either your constructor or via property injection.
You'll have to do something similar I think for your calls to the various System.IO classes, unless you actually have a place on the file system setup and ready to do for your tests.

Answer 2

I would use IoC and introduce some interface property that would provide access to select HttpContext properties. When testing you just use your implementation which would feed method with needed values during the test.
here is some pesudo-code:
public class FileService : IFileService
{
// injected property
public IHttpContext CurrentContex {get;set;}
public string GetEmployeePicLocation(Employee employee)
{
string AgentFilesDirectory = "~\\AgentFiles\\";
Image newImage = new Image();
DirectoryInfo diSubPath = new DirectoryInfo(CurrentContex.Server.MapPath(AgentFilesDirectory + employee.User_Name));
// ...
}
}
PS: I think you're looking for a HttpContext stub. Please have a look here http://martinfowler.com/articles/mocksArentStubs.html

Answer 3

I see that you got some answers on how to mock it, just thought I'd suggest an alternate method that may be simpler when it takes effort to replace a static access;
If you move the access to HttpContext to a virtual method;
protected virtual DirectoryInfo GetEmployeeDirInfo(Employee employee)
{
return new DirectoryInfo(
HttpContext.Current.Server.MapPath(AgentFilesDirectory + employee.User_Name));
}
and replace the old line doing the access with;
DirectoryInfo diSubPath = GetEmployeeDirInfo(employee);
...you can suddenly trivially replace the access by "mocking" the class manually;
internal class FileServiceMock : FileService
{
protected override DirectoryInfo GetEmployeeDirInfo(Employee employee)
{
return new DirectoryInfo("C:\\Temp");
}
}
...and just test FileServiceMock in your test.
void Testmethod() {
FileService service = new FileServiceMock();
...

Answer 4

alternatively use HostingEnvironment.MapPath . .it doesnt need httpcontext . .avoid httpcontext