debugger; and breakpoints don't work with node --inspect

[snapwich]

Currently breakpoints can be set for use with node debug using the keyword debugger;, but any breakpoints set with debugger; when using node --inspect are ignored. This only applies to the test code; breakpoints set with debugger; within Jest or other node_module libraries are honored.

I set up a test repository to demonstrate the difference: https://github.com/snapwich/jest-inspect. Both methods can be tested by pulling the repo and running the following:

npm install

// works
node debug --debug-brk ./node_modules/.bin/jest -i

// doesn't honor "debugger;"
node --inspect --debug-brk ./node_modules/.bin/jest -i

Also, after the initial run-through with node --inspect, breakpoints can be applied to the code in the Sources tab. Any breakpoints placed in test code (such as __tests__/jest.js in jest-inspect repo above) will be ignored, but breakpoints placed in any other files (Jest or other node_modules code) will work correctly when the suite is rerun.

node --inspect is only available in node v6.3.0+ and I'm running on OSX using node v6.4.0 and npm v3.10.3

/cc @kentcdodds

[maximderbin]

run into the same problem today

[maximderbin]

Also in your example if I run npm run debug

  6
  7     // break won't be triggered
> 8     debugger;
  9
 10     expect(test).toBe(true);
test
ReferenceError: test is not defined

Am I doing something wrong or it doesn't have access to context?

[snapwich]

@maximderbin not sure why you're getting that ReferenceError, test should be defined just a few lines above there: https://github.com/snapwich/jest-inspect/blob/master/__tests__/jest.js#L5

edit - just tested, you need to type repl before typing test so the code runs in the proper context.

[maximderbin]

related issue facebook/create-react-app#594

[cpojer]

This is interesting. Is it possible that node's --debug flag doesn't work when using the vm module to create a context?

[aleclarson]

Any news on this?

[aleclarson]

Was this ever working before?

I don't think vm.runInContext supports the debugger protocol.

This article mentions port forwarding to support debugging VM code. Not sure if that's relevant.

Beyond that, maybe it's possible to use websockets within the VM (to support the debugger protocol)?

What do you think, @cpojer?

[gbiryukov]

maybe it is possible to run tests without vm context in debug mode?

[damonbauer]

This issue is the biggest reason why I can't switch to Jest. Any updates or ideas on how to make progress?

[cpojer]

I think we need to create a repro without Jest and submit an issue to the node.js bugtracker.

[Met48]

This NodeJS issue looks related: nodejs/node#7593.

Repro case is minimal:

var vm = require('vm');
new vm.Script('debugger;').runInContext(vm.createContext());
debugger;

Will break three times with node debug index.js but only twice with node --inspect --debug-brk index.js

[kmcq]

@cpojer do you think it's a good idea to change the content of http://facebook.github.io/jest/docs/troubleshooting.html#tests-are-failing-and-you-don-t-know-why to reflect that this doesn't work yet? I'm happy to submit a PR for this if that would be helpful -- what should the section say? Delete it? Say "coming soon"?

(I love Jest by the way! It makes React testing even more awesome)

[bent]

I've created a PR for an update to the docs on this: #1998

[guy-kdm]

It seems that node-inspector is not maintained anymore and does not support node 7.*. When I use
node --debug-brk --inspect ./node_modules/react-scripts/node_modules/.bin/jest -i
With CRA and node 7.1 it seems to load correctly in the dev tools and than hang with "waiting for debugger to disconnect" (even though execution is free)

[thomasklein]

Hi guys, any update on this issue?

[trodrigues]

Thanks to all who got this to work 👏

[WickyNilliams]

So is there anything in particular that needs to be done beyond installing latest node v8.4.0? Could someone post their vscode launch.json for this?

This vscode launch config works for me :)

    {
      "name": "Debug Jest tests",
      "type": "node",
      "request": "launch",
      "runtimeArgs": [
        "--inspect",
        "./node_modules/.bin/jest",
        "-i"
      ],
      "cwd": "${workspaceRoot}",
      "protocol": "inspector",
      "console": "integratedTerminal"
    }

[trodrigues]

You just need to run it in "the new way". That is, with inspect, --inspect or --inspect-brk. See https://nodejs.org/en/docs/inspector/ for more info on the various ways of running it and things that can connect to it.

The aforementioned jest-environment-node-debug is not necessary.

[cpojer]

node --inspect --inspect-brk node_modules/bin/jest should work with node 8.4.0 out of the box. I'm so happy this finally works, it was one major issue that was making it hard to debug JavaScript tests.

[Timer]

For those using create-react-app / react-scripts:

./node_modules/.bin/react-scripts --inspect-brk test --env=jsdom --runInBand

Make sure you're on react-scripts@^1.011!

[sparebytes]

Breakpoints don't hit for me.

• Windows 10
• Node 8.4
• VSCode 1.15.1
• Jest 20

See the example project here:
https://github.com/sparebytes/jest-debug-example

This is the launch config:

{
    "name": "Debug Jest tests",
    "type": "node",
    "request": "launch",
    "sourceMaps": true,
    "runtimeArgs": [
        "--inspect-brk",
        "--nolazy",
        "./node_modules/jest/bin/jest.js",
        "-i"
    ],
    "cwd": "${workspaceRoot}",
    "protocol": "inspector",
    "console": "integratedTerminal"
}

[Phlow2001]

@sparebytes in your console, check your node --version, make sure it's 8.4. The following launch config worked for me with your same specs:

  {
    "name": "Debug Jest tests",
    "type": "node",
    "request": "launch",
    "program": "${workspaceRoot}\\node_modules\\jest\\bin\\jest.js",
    "args": [
      "--runInBand",
      "--no-cache"
    ],
    "runtimeArgs": [
      "--inspect-brk"
    ],
    "cwd": "${workspaceRoot}",
    "protocol": "inspector",
    "console": "integratedTerminal"
  }

[SudoPlz]

Still doesn't work for me on 8.4.0 and I've tried everything.

It looks like the break points become red (get activated) after the tests have finished.. Any ideas?

[ghost]

+1
It does not work for me too

[robophil]

@yevhenchmykhunep did you give this a shot?

./node_modules/.bin/react-scripts --inspect-brk test --env=jsdom --runInBand

By @Timer

[FossPrime]

I'm having the issue on node v10.5.0 and jest@23.2.0 node --inspect --inspect-brk ./node_modules/jest/bin/jest.js

The break on first line works, but the debugger calls don't stop :(

[ghost]

Looks like it not the jest problem, but nodejs problem. I Having the same issue with debugging my application as well. I'm using node v8.11.3

[jcollum]

I can get the debugger to spawn and hit debugger lines in node 8.

"test:debug": "node --inspect-brk node_modules/.bin/jest --runInBand -t",

and

nvm exec 8 yarn test:debug

However, this debugger line will not cause a stop:

describe.skip('With Enzyme', () => {
  it('ArticleSidebar component displays', () => {
    debugger;

This line will:

// this code is in not in tests
import { config } from './nextConfig';
let log, logError;
debugger; 

So the moral of the story for me appears to be: don't expect debugger breaks to be hit if they are in Jest test code. Why? Maybe someone smarter than me wants to figure that out 😸

[jchani]

For those still stuck with this problem, debugging in Chrome DevTools works with the debugger statement. Not an ideal solution, but a decent workaround:

To debug in Google Chrome (or any Chromium-based browser), simply open your browser and go to chrome://inspect and click on "Open Dedicated DevTools for Node", which will give you a list of available node instances you can connect to. Simply click on the address displayed in the terminal (usually something like localhost:9229) after running the above command, and you will be able to debug Jest using Chrome's DevTools.

The Chrome Developer Tools will be displayed, and a breakpoint will be set at the first line of the Jest CLI script (this is done simply to give you time to open the developer tools and to prevent Jest from executing before you have time to do so). Click the button that looks like a "play" button in the upper right hand side of the screen to continue execution. When Jest executes the test that contains the debugger statement, execution will pause and you can examine the current scope and call stack.

Source: https://jestjs.io/docs/en/troubleshooting#tests-are-failing-and-you-don-t-know-why

[FossPrime]

@jchani even with this method, debug statements inside tests will still not break. As @jcollum pointed out. Even with break on first line enabled. Break points inside tests is the type we all want more than any other. Debugging why a test stopped working is a pita without this ability.

vuematerial/vue-material#1840 @Samuell1 why do you want to stick with jest 22 when we have 4 tests failing on dev... imo no commit should ever be allowed with failing tests.

[FossPrime]

For Vue users: if your debugger statements aren't working... try moving them to your component instead of the jest code, do as little as possible in jest and just check the state of your fixtures... at least until the nodejs team fixes this issue.

My debugger calls are ininput-speed.vue. I realise this is not ideal, but it beats not having debugging or forgoing tests because they are too hard to build.

import Vue from 'vue'
import { mount } from 'avoriaz'
import f1 from '../fixtures/input-speed.vue'

test('should work with phones autocorrect', async () => {
  const wrapper = await mount(f1, {})
  const vm = wrapper.vm

  await wrapper.vm.$nextTick()

  // should work with android autocorrect without waiting
  expect(vm.form.server).toBe('autocorrect')
  expect(vm.noBind).toBe('Not data binded')  // Should work without data binding
})

[brien-givens]

Adding this for anyone having this issue while using the --watch option - debugger statements are ignored with --watch, however adding --no-cache fixes the issue. I can confirm that the following works consistently on node 10.8.0:

node --inspect-brk node_modules/.bin/jest --runInBand --no-cache --watch

[prufrock123]

for node 6.x, instead of node --inspect-brk, try node inspect (note, the lack of hyphens)

nvm

[bernardoadc]

This extension has helped me: https://chrome.google.com/webstore/detail/nodejs-v8-inspector-manag/gnhhdgbaldcilmgcpfddgdbkhjohddkj/related?hl=en

It detects node --inspect and opens devTools in Chrome for that websocket. debugger statements and breakpoints set manually on devtools has worked!

[jcollum]

It's funny, it seems like i have better luck here if I turn OFF Node Inspector Manager and use chrome://inspect instead.

[june07]

@jcollum As the developer of NiM... anything, in particular, I should be aware of?

[jcollum]

Sorry, I don't have anything specific here. Sometimes hitting a breakpoint in a file that's behind a sourcemap is just flaky. Next time I need to debug a jest test I'll give NIM another shot.

[tschoartschi]

I wanted to report back that we encountered the same problem as mentioned by @brien-givens

As he said adding --no-cache solves the problem for us (details see here: #1652 (comment))

@brien-givens thanks for sharing your solution :-)

[yury-kozlov]

For me the issue was with two *.test.js files with the same name (located in different folders). When I removed one of them, debugger was hit in the other without problems.
Configuration:
"name": "Debug Jest Test", "type": "node", "request": "launch", "program": "${workspaceRoot}/node_modules/jest/bin/jest", "args": [ "${fileBasenameNoExtension}", ], "console": "integratedTerminal"

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