Nock fixtures: Ignore request body when matching - nock

Question

In the Readme for nock it explains how one can ignore the request body.
I am using the fixtures feature of nock and I need to ignore the request body (at least partially). How can I do this? Can I write a regex in the body field of the json entries in the fixtures files?

Answer 1

I solved it myself after some painful digging. Here is the solution:
I am trying to nock requests to the Kraken API. The request for the endpoint /0/private/TradesHistory is of method POST and sends a body containing a "query string like" string. For example the body will look like ofs=50&nonce=xxx. The nonce value changes with each request, so I want to ignore it to when looking for a matching nock. (The nonce can only be used once, it would make no sense for the client library to send the same value again).
So I have to add a "preprocessing" function as a config object to the call to nockBack like so:
import * as queryString from 'query-string'
import { back } from 'nock'
import * as path from 'path'
const before = (scope: any) => {
scope.filteringRequestBody = (body: string, aRecordedBody: string) => {
const { of: currentOffset, } = queryString.parse(`?${body}`) //Prepend a `?` so it is actually a query string.
const { of: recordedOffset, } = queryString.parse(`?${body}`)
if (!(currentOffset || recordedOffset)) {//This is the case where no offset is set. There is only possible recorded body in my case that matches this: The other body which has no offset. I replace the body with the recorded body to produce a match.
return aRecordedBody
}
if (currentOffset === recordedOffset) {//This is the case where the sent body has the same offset as the recorded body. I replace the body with the recorded body in order to produce a match.
return aRecordedBody
}
return body
}
}
back.fixtures = `${__dirname}/nockFixtures/`
const { nockDone } = back('nocks.json',{before})
...//Run my queris
nockDone()
Now it works like a charm.