grahpql-jit-subscription.test.ts

import { makeExecutableSchema } from "@graphql-tools/schema";
import { parse } from "graphql";
import { compileQuery, isCompiledQuery } from "../execution";

function isAsyncIterable<T>(val: any): val is AsyncIterableIterator<T> {
  return val != null && typeof val[Symbol.asyncIterator] === "function";
}

const schema = makeExecutableSchema({
  typeDefs: `
    type Subscription {
      nodes: Node
    }
    type Node {
      id: ID
    }
  `,
  resolvers: {
    Subscription: {
      nodes: {
        async *subscribe() {
          for (let i = 0; i < 3; i++) {
            yield {
              id: i.toString()
            };
          }
        },
        /**
         * Without this resolver, the tests below would fail
         */
        resolve(source) {
          return source;
        }
      }
    }
  }
});

async function subscribe(query: string) {
  const document = parse(query);
  const prepared = compileQuery(schema, document);
  if (!isCompiledQuery(prepared)) return prepared;
  return prepared.subscribe!({}, {}, {});
}

describe("subscription happy case", () => {
  test("nodes and ids", async () => {
    const sub = await subscribe(`
      subscription {
        nodes {
          id
        }
      }
    `);
    if (isAsyncIterable(sub)) {
      let i = 0;
      for await (const val of sub) {
        expect(val.data?.nodes?.id).toBe((i++).toString());
      }
    }
  });
});