private static AssertionException wrongTypeError(String msgPrefix, ICell expectedCell, CellValue actualValue)
 {
     return new AssertionException(msgPrefix + " Result type mismatch. Evaluated result was "
             + actualValue.FormatAsString()
             + " but the expected result was "
             + formatValue(expectedCell)
             );
 }
 private static void ConfirmErrorResult(String msgPrefix, int expectedErrorCode, CellValue actual)
 {
     if (actual.CellType != CellType.ERROR)
     {
         throw new AssertionException(msgPrefix + " Expected cell error ("
                 + ErrorEval.GetText(expectedErrorCode) + ") but actual value was "
                 + actual.FormatAsString());
     }
     if (expectedErrorCode != actual.ErrorValue)
     {
         throw new AssertionException(msgPrefix + " Expected cell error code ("
                 + ErrorEval.GetText(expectedErrorCode)
                 + ") but actual error code was ("
                 + ErrorEval.GetText(actual.ErrorValue)
                 + ")");
     }
 }