anchor.diff:  
           let changed = bunnyHillProjection.Change.Invoke(bh, systemContext, change)
   
  -        Assert.AreEqual(bh.DownrangeWindow.Start, changed.DownrangeWindow.Start)
  -        Assert.AreEqual(newWindowEnd, changed.DownrangeWindow.End)
  +        let actualWindow = changed.DownrangeWindow
  +        Assert.AreEqual<DownrangeWindow>(expectedWindow, actualWindow)
  
positive.code:     [<TestMethod>]
      member __.``Change window start`` () =
  
          let bh = { DownrangeWindow = { Start = 3.0<m>; End = 5.0<m> } }
          let newWindowStart = bh.DownrangeWindow.Start + 0.1<m>
          let change = ChangeWindowStart newWindowStart
          let systemContext = {
              SystemType = ArisSystemType.Aris3000
  
negative.code:             AuxLens = AuxLensType.None
              AntialiasingPeriod = 0<Us>
          }
  
          let constrained = bunnyHillProjection.Constrain.Invoke(bh, ctx)
  
          Assert.AreNotEqual<BunnyHillSettings>(bh, constrained, "Must show *some* constraint!")
  