anchor.diff:                  let f2  = "H2O" |> parseFormulaString 
                   let res = substract f1 f2 |> toString 
                   Expect.equal res "H0.00 O0.00" "Substraction of formulas failed"
  -
           ]
       
       open BioFSharp.Mass  
  
positive.code:                     RelAtomicMass = 1.007947
                      }
                  let H1' = create "H" 1 1 1.00782503207 0.999885 1.007947
                  Expect.isTrue (H1=H1') (sprintf "%A <> %A, check parameter order 'create'" H1 H1')
          ]
      
      open BioFSharp.Elements
  
negative.code:                         Expect.floatClose Accuracy.high min expMin "Delta mass calculation failed, lower border is incorrect."
                  yield 
                      testCase "upper_Border" <| fun () ->
                          Expect.floatClose Accuracy.high max expMax "Delta mass calculation failed, upper border is incorrect."                   
              ]        
          ]
          