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.NET Automated Testing with Session and Microsoft Fakes

I am working on a project that uses session and application level calls nested deep within the code. It is not practical to refactor those calls to pass in the values needed and make Unit Testing possible through dependency injection, so I needed to find a way to create automated tests that would not crash on those calls. I researched and tried out many different approaches. Ultimately what I came up with was to use Microsoft's Fakes to mimmic the Session and Application calls. I was helped greatly by this post,Testing Untestable Code Thanks to MS Fakes, and commented my code with his link in case others at my company need to view it.

I created a class that my Web Tests can inherit from that will handle the setup of these Fake calls.

Imports System.IO
Imports System.Web
Imports System.Web.Fakes
Imports Microsoft.QualityTools.Testing.Fakes

<TestClass()> Public Class SessionTestBase
 Private _fakeHttpContext As IDisposable

 <TestInitialize()> Public Sub BeforeEachTestBase()
  _fakeHttpContext = ShimsContext.Create

  System.Web.Fakes.ShimHttpContext.CurrentGet = Function()
                                                  Return New HttpContext(New HttpRequest("", "", ""), New HttpResponse(New StringWriter()))
                                                End Function


 End Sub

 Private Sub SetupSessionState()
  Dim sessionState As New System.Web.SessionState.Fakes.ShimHttpSessionState
  sessionState.SessionIDGet = Function()
                                Return "1"
                              End Function

  Dim sessionDictionary As New Dictionary(Of String, Object)
  sessionState.ItemSetStringObject = Sub(key As String, value As Object)
                                       sessionDictionary.Add(key, value)
                                     End Sub
  sessionState.ItemGetString = Function(key As String)
                                 If sessionDictionary.ContainsKey(key) Then
                                   Return sessionDictionary(key)
                                   Return Nothing
                                 End If
                               End Function

  System.Web.Fakes.ShimHttpContext.AllInstances.SessionGet = Function(o As Object)
                                                               Return sessionState
                                                             End Function
 End Sub

 Private Sub SetupApplicationState()
  Dim applicationState As New ShimHttpApplicationState
  Dim applicationDictionary As New Dictionary(Of String, Object)
  applicationState.ItemSetStringObject = Sub(key As String, value As Object)
                                           applicationDictionary.Add(key, value)
                                         End Sub
  applicationState.ItemGetString = Function(key As String)
                                     If applicationDictionary.ContainsKey(key) Then
                                       Return applicationDictionary(key)
                                       Return Nothing
                                     End If
                                   End Function

  System.Web.Fakes.ShimHttpContext.AllInstances.ApplicationGet = Function(o As Object)
                                                                   Return applicationState
                                                                 End Function
 End Sub

 <TestCleanup()> Public Sub AfterEachTestBase()
  If _fakeHttpContext IsNot Nothing Then
  End If
 End Sub
End Class


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