Mocked values for fields that take in parameters are not respected when provided in a list

[nickiepucel]

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---

Describe the bug

Mocked values for fields that take in parameters are not respected when provided in a list.

If you have a field on an object that takes in parameters, and you attempt to mock that field in a list of those objects, the mocked value for the field is ignored, and a default value is provided instead.

To Reproduce Steps to reproduce the behavior:

The following code can be used to reproduce the issue

import { addMocksToSchema } from "@graphql-tools/mock";
import { makeExecutableSchema } from "@graphql-tools/schema";
import { graphql } from "graphql";

const typeDefs = `#graphql
  type UserGroup {
    id: ID!
    users: [User!]!
  }

  type User {	
    id: ID!
    # User has a nullable membership field that takes in some input
    membership(param: String!): Membership
  }

  type Membership {
    id: ID!
  }

  type Query {
    getUserGroup: UserGroup
  }
`;

const query = /* GraphQL */ `
  query GetUserGroup {
    getUserGroup {
      id
      users {
        id
        # input is provided in the query here
        membership(param: "test") {
          id
        }
      }
    }
  }
`;

const mockSchema = addMocksToSchema({
  schema: makeExecutableSchema({
    typeDefs,
  }),

  mocks: {
    UserGroup: () => ({
      users: [
        // Neither of these overrides work
        { membership: null },
        { membership: { id: "mock-membership-id" } },
      ],
    }),
  },
});

graphql(mockSchema, query).then((result) => console.log("Got result", result));

The result that is printed out:
As json

{
  "data": {
    "getUserGroup": {
      "id": "875ca18b-66a7-4633-a47e-1d57de90a176",
      "users": [
        {
          "id": "cbb42248-9cbd-48ab-a86c-438cd41ec6f6",
          "membership": {
            "id": "ee1a9260-4e4e-4778-8ef0-dd8754c88c6f"
          }
        },
        {
          "id": "51742853-07b0-4666-906e-2377d21433de",
          "membership": {
            "id": "6e8e08af-398a-4f1a-806b-f8b2d92a43b0"
          }
        }
      ]
    }
  }
}

Screenshot of browser console:

Expected behavior

The overrides should work, and the returned result should be:

{
  "data": {
    "getUserGroup": {
      "id": "f1d3506d-9901-412e-aee1-0114f76a4f62",
      "users": [
        {
          "id": "ca41e01f-e45e-4f10-8eb5-f143432fdd69",
          "membership": null
        },
        {
          "id": "6cfba26e-1b7e-4a4e-9dec-99eb2fa54e1d",
          "membership": {
            "id": "mock-membership-id"
          }
        }
      ]
    }
  }
}

Environment:

• OS: macOS 14.6.1
• @graphql-tools/mock: 9.0.1
• @graphql-tools/schema: 10.0.2
• graphql: 15.8.0
• NodeJS: v20.11.1

Additional context

The overrides work as expected with minor tweaks:

• If you make param optional, and don't pass one in in the query, the overrides work
• Overriding membership via mocking User works as expected

User: () => ({ membership: null }) // this works

• The bug also presents itself when the field returns a primitive rather than an object type

type User {
  # mocks provided for name in the list would also be ignored
  name(param: String!): String
}