anchor.diff:  nuget FAKE = 1.1
   nuget SignalR = 3.3.2"""
   
  -    try
  -        DependenciesFile.FromCode(config).Add("fAKe","") |> ignore
  -        failwith "adding the same package did not throw"
  -    with e -> 
  -        e.Message |> shouldEqual <| sprintf "%s has already package %s" Constants.DependenciesFile "fAKe"+    DependenciesFile.FromCode(config).Add("fAKe","") |> ignore
positive.code: 
  
  [<Test>]
  let ``should fail if package already exists``() = 
      let config = """source http://nuget.org/api/v2
  
  nuget Castle.Windsor-log4net ~> 3.2
  
negative.code: nuget FAKE = 1.1
  nuget SignalR = 3.3.2"""
  
      DependenciesFile.FromCode(config).Add("FAKE","") |> ignore
      
  [<Test>]
  let ``should not fail if package already exists - case insensitive``() = 
      let config = """source http://nuget.org/api/v2
  
  nuget Castle.Windsor-log4net ~> 3.2
  