Load a file once the Jest environment has been properly deconstructed

Question

Load a file once the Jest environment has been properly deconstructed

I am currently working on developing a straightforward API using Express, and I have encountered an issue while attempting to add tests with Jest. When running the tests, an error is displayed:

ReferenceError: You are trying to `import` a file after the Jest environment has been torn down.

      at BufferList.Readable (node_modules/readable-stream/lib/_stream_readable.js:179:22)
      at BufferList.Duplex (node_modules/readable-stream/lib/_stream_duplex.js:67:12)
      at new BufferList (node_modules/bl/bl.js:33:16)
      at new MessageStream (node_modules/mongodb/lib/cmap/message_stream.js:35:21)
      at new Connection (node_modules/mongodb/lib/cmap/connection.js:52:28)
/home/jonathangomz/Documents/Node/Express/Devotionals/node_modules/readable-stream/lib/_stream_readable.js:111
  var isDuplex = stream instanceof Duplex;
                        ^

TypeError: Right-hand side of 'instanceof' is not callable

Concerns arise regarding the reliability of the test results right after Jest encounters this issue:

https://i.sstatic.net/87bam.png

The test script is as follows:

const app = require("../app");
const request = require("supertest");

describe("Testing root router", () => {
  test("Should test that true === true", async () => {
    jest.useFakeTimers();
    const response = await request(app).get("/");
    expect(response.status).toBe(200);
  });
});

The Jest configuration in my package.json file is set as:

"jest": {
    "testEnvironment": "node",
    "coveragePathIgnorePatterns": [
      "/node_modules/"
    ]
  }

Additional Notes:

Despite attempting to use jest.useFakeTimers(), the issue persists and it seems like I may be implementing it incorrectly. I have also tried adding it within the beforeEach method without success.

javascript express jestjs

Answer 1

Answer №1

For me, the solution was adding the package to the transformIgnorePatterns section in the jest configuration file.

Answer 2

For me, the solution was adding the package to the transformIgnorePatterns section in the jest configuration file.

Answer 3

Answer №2

To enhance your testing capabilities, try incorporating jest.useFakeTimers() immediately following all imports.

Have you considered converting your test to be async?

const app = require("../app");
const request = require("supertest");

describe("Testing root router", async () => {
  test("Ensuring that true === true", async () => {
    jest.useFakeTimers();
    const response = await request(app).get("/");
    expect(response.status).toBe(200);
  });
});

Answer 4

To enhance your testing capabilities, try incorporating jest.useFakeTimers() immediately following all imports.

Have you considered converting your test to be async?

const app = require("../app");
const request = require("supertest");

describe("Testing root router", async () => {
  test("Ensuring that true === true", async () => {
    jest.useFakeTimers();
    const response = await request(app).get("/");
    expect(response.status).toBe(200);
  });
});

Answer 5

Answer №3

In order to manipulate timers in your asynchronous test, make sure to include jest.useFakeTimers('modern') before the asynchronous call. Then, add jest.runAllTimers() after the asynchronous call to fast-forward the timers for accurate testing.

const app = require("../app")
const request = require("supertest")

describe("Testing root router", () => {
  test("Should test that true === true", async () => {

    //Before asynchronous call
    jest.useFakeTimers("modern")

    const response = await request(app).get("/")

    //After asynchronous call
    jest.runAllTimers()

    expect(response.status).toBe(200)
  })
})

Answer 6

In order to manipulate timers in your asynchronous test, make sure to include jest.useFakeTimers('modern') before the asynchronous call. Then, add jest.runAllTimers() after the asynchronous call to fast-forward the timers for accurate testing.

const app = require("../app")
const request = require("supertest")

describe("Testing root router", () => {
  test("Should test that true === true", async () => {

    //Before asynchronous call
    jest.useFakeTimers("modern")

    const response = await request(app).get("/")

    //After asynchronous call
    jest.runAllTimers()

    expect(response.status).toBe(200)
  })
})

Answer 7

Answer №4

For those running Jest, consider using the --testTimeout=10000 flag to extend the timeout and avoid potential issues.

Referenced from Testing NodeJs/Express API with Jest and Supertest

The --testTimeout flag allows you to adjust Jest's default timeout from 5000ms to 10000ms, which can be crucial for database refresh requirements before testing.

Answer 8

For those running Jest, consider using the --testTimeout=10000 flag to extend the timeout and avoid potential issues.

Referenced from Testing NodeJs/Express API with Jest and Supertest

The --testTimeout flag allows you to adjust Jest's default timeout from 5000ms to 10000ms, which can be crucial for database refresh requirements before testing.

Load a file once the Jest environment has been properly deconstructed

Additional Notes:

Answer №1

Answer №2

Answer №3

Answer №4

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