/**
  * Calculates the fee based on fee event and amount
  *
  * @param eventType which fee event to use
  * @param amount amount in GBP
  * @param channel online or paper/default
  * @returns {Promise.<FeeOutcome>} promise containing the Fee outcome (including fee amount in GBP)
  */
 static async calculateFee (eventType: string, amount: number, channel: string): Promise<FeeOutcome> {
   if (StringUtils.isBlank(eventType)) {
     throw new Error('Fee eventType is required')
   }
   if (StringUtils.isBlank(channel)) {
     throw new Error('Fee channel is required')
   }
   ClaimValidator.claimAmount(amount)
   const feeUri: string = `${feesUrl}/fees-register/fees/lookup?service=${service}&jurisdiction1=${jurisdiction1}&jurisdiction2=${jurisdiction2}&channel=${channel}&event=${eventType}&amount_or_volume=${amount}`
   const options = {
     uri: feeUri
   }
   return request(options).then(function (response) {
     return plainToClass(FeeOutcome, response as object)
   })
 }

    ErrorHandling.apply(async (req: express.Request, res: express.Response, next: express.NextFunction): Promise<void> => {
      const form: Form<ClaimAmountBreakdown> = req.body

      if (form.hasErrors()) {
        renderView(form, res)
      } else {
        form.model.removeExcessRows()
        ClaimValidator.claimAmount(form.model.totalAmount())
        const draft: Draft<DraftClaim> = res.locals.claimDraft
        const user: User = res.locals.user

        draft.document.amount = form.model
        await new DraftService().save(draft, user.bearerToken)

        res.redirect(Paths.interestPage.uri)
      }
    })

 expect(() => ClaimValidator.claimAmount(null)).to.throw(Error, 'Claim amount must be a valid numeric value')