anchor.diff:      |> should equal false
   
   [<Test>]
  -let ``parse - move down``() =
  +let ``ProjectSystem - parse - move down``() =
       let pf = FsProject.parse astInput
       let pf' = FsProject.moveDown "app.config" pf
       let files = pf'.SourceFiles.AllFiles()
  
positive.code:     pf'.SourceFiles.AllFiles() |> Seq.length |> should be (equal 3)
  
  [<Test>]
  let ``parse - remove file``() =
      let pf = FsProject.parse astInput
      let f = "FixProject.fs"
      let pf' = FsProject.removeSourceFile f pf
      pf'.SourceFiles.AllFiles() |> Seq.length |> should be (equal 2)
  
  [<Test>]
  let ``parse - remove not existing file``() =
      let pf = FsProject.parse astInput
      let f = "FixProject2.fs"
      let pf' = FsProject.removeSourceFile f pf
      pf'.SourceFiles.AllFiles() |> Seq.length |> should be (equal 3)
  
  [<Test>]
  let ``parse  - order file``() =
      let pf = FsProject.parse astInput
      let pf' = pf |> FsProject.moveUp "a_file.fs" |> FsProject.moveUp "a_file.fs" 
      let files = pf'.SourceFiles.AllFiles()
  
negative.code:     files |> Seq.length |> should be (equal 3)
  
  [<Test>]
  let ``ProjectSystem - parse - add reference``() =
      let pf = FsProject.parse astInput
      let r = {Reference.Empty with Include = "System.Xml"}
      let pf' = FsProject.addReference r pf
      pf'.References |> Seq.length |> should be (equal 6)
  
  [<Test>]
  let ``ProjectSystem - parse - add existing reference``() =
      let pf = FsProject.parse astInput
      let r = {Reference.Empty with Include = "System"}
      let pf' = FsProject.addReference r pf
      pf'.References |> Seq.length |> should be (equal 5)
  
  [<Test>]
  let ``ProjectSystem - parse - remove reference``() =
      let pf = FsProject.parse astInput
      let r = {Reference.Empty with Include = "System"}
      let pf' = FsProject.removeReference r pf
      pf'.References |> Seq.length |> should be (equal 4)
  
  [<Test>]
  let ``ProjectSystem - parse - remove not existing reference``() =
      let pf = FsProject.parse astInput
      let r = {Reference.Empty with Include = "System.Xml"}
      let pf' = FsProject.removeReference r pf
      pf'.References |> Seq.length |> should be (equal 5)
  
  [<Test>]
  let ``ProjectSystem - parse - move up``() =
      let pf = FsProject.parse astInput
      let pf' = FsProject.moveUp "App.config" pf
      let files = pf'.SourceFiles.AllFiles()
  