Mock data based on query path

[bengry]

I'm trying to set up a mock server for testing purposes that returns mock data that is deterministic across runs - i.e. using seeds.

However, I don't want all calls returning in the same info (e.g. all Strings to be "Hello World"), so my idea was to use the query path and variables as a seed for something like Fakerjs - i.e.

type Todo {
  id: ID!
  text: String!
  completed: Boolean!
}

type TodoEdge {
  node: Todo!
  cursor: String!
}

type TodoConnection {
  edges: [TodoEdge]
  pageInfo: PageInfo!
}

type PageInfo {
  hasNextPage: Boolean!
  hasPreviousPage: Boolean!
  startCursor: String
  endCursor: String
}

type Query {
  todos(first: Int, after: String, last: Int, before: String): TodoConnection!
}

and the query

query {
  todos(first: 10) {
    edges {
      node {
        id  # hash('todos' + JSON.stringify({ first: 10 }) + 'edges' + 'node' + <index> + 'id')
        text # hash('todos' + JSON.stringify({ first: 10 }) + 'edges' + 'node' + <index> + 'text')
        ...
      }
  }
}

I'm unsure if achieving this using @graphql-tools/mock is possible, and if so - how? The public API for custom-resolving scalars does not pass the query path to the resolver.

Ideally, I'd do something like this:

import { addMocksToSchema, mockServer } from '@graphql-tools/mock'

// cache of a query path to Faker instance, so multiple calls to the same thing increment the internal count of faker, and not create a new instance, removing the usefulness of a seed
declare const fakerInstances: {
  /* Get or create a Faker instance for the given context */
  get(context: { path: string, variables?: object }): Faker;
}

// Mock object
const mocks = {
  Int: ({ path, variables }) => fakerInstances.get({ path, variables }).number.int(),
  Float: ({ path, variables }) => fakerInstances.get({ path, variables }).number.float(),
  String: ({ path, variables }) => fakerInstances.get({ path, variables }).word.sample(),
  DateTime: ({ path, variables }) => fakerInstances.get({ path, variables }).date.recent().toISOString()
}
 
const server = mockServer(schema, mock);

Any help would be greatly appreciated.