Jest: Jest loops in watch mode

[FezVrasta]

Do you want to request a _feature_ or report a _bug_?
bug

What is the current behavior?
Jest --watch loops

If the current behavior is a bug, please provide the steps to reproduce and
either a repl.it demo through https://repl.it/languages/jest or a minimal
repository on GitHub that we can yarn install and yarn test.

Mine is a rewired CRA with these Jest options:

"jest": {
    "setupFiles": [
      "raf/polyfill"
    ],
    "coverageThreshold": {
      "global": {
        "branches": 30,
        "functions": 34,
        "lines": 39,
        "statements": 34
      }
    },
    "testResultsProcessor": "jest-bamboo-formatter",

What is the expected behavior?

Jest watch shouldn't loop

Please provide your exact Jest configuration and mention your Jest, node,
yarn/npm version and operating system.
Node v8.9.0
Yarn 1.3.2
Hest 20.0.4

[thymikee]

Can you send a repo with the issue happening?

[FezVrasta]

I can't share the repo and I fear there's something in my repo that's causing this problem...

[FezVrasta]

I thought it could be this (https://github.com/facebook/jest/issues/4635), but I tried the suggested fix and it doesn't help 🤷‍♀️

[thymikee]

Can you profile if anything is triggering a change in your FS. How it behaves it there are tests, or you press a or run with --watchAll?

[FezVrasta]

@thymikee may you provide a source where I can read how to profile the FS changes?

With --watchAll I get the same problem. If I run all the tests, they run, and then they automatically run again

[thymikee]

Should do the trick:
https://stackoverflow.com/questions/1515730/is-there-a-command-like-watch-or-inotifywait-on-the-mac

[FezVrasta]

I see that jest.json is changing, but I already excluded it with:

    "watchPathIgnorePatterns": [
      "<rootDir>/jest.json"
    ],

[thymikee]

It's really hard to tell something without the code in front of you. I would try other patterns to ignore (e.g. without rootDir, using absolute path, more generic, whatever) and monkey-patch setting watchPathIgnorePatterns to see what it gets eventually

[FezVrasta]

I can't find the watch file to monkey patch, where is it?

I tried with require.resolve('./jest.json') but it still loops

[SimenB]

What I did was add a console.log to the change event linked in that issue. Then you can see what file triggers the watcher

[FezVrasta]

The file is jest.json, but I should have already ignored it 🤷‍♀️

[SimenB]

Just that file? Without a repro it's hard to help you...

[FezVrasta]

Yeah I know... for now I managed to enable the bamboo reporter only when the tests run on CI, so that I don't encounter this problem, I guess it's also a good thing because doing so I don't run useless code on local machines.

[SimenB]

Closing as there's not much we can do without a repro. Feel free to keep bouncing ideas here!

[kyhy]

Following workaround in https://github.com/facebook/jest/issues/4635 fixed the issue.

https://github.com/facebook/jest/issues/4635#issuecomment-337132601

[jlangr]

I experience this problem with a fairly vanilla create-react-app learning project. See https://github.com/susiehill/amortization for the repo. I tried the workaround in #4635, which first required that I do an eject, but that did not appear to work.

This problem appears intermittently. _Sometimes_, blowing away node_modules and redoing the npm install fixes the problem, but only temporarily--it seems to invariably resurface later.

At least once, it sat there when I started (because it didn't need to re-rerun tests from the last run), but the problem started when I pressed a.

MacOS 10.13.3
Jest 20.0.4 (as installed via create-react-app)
Node 8.2.1
NPM 5.7.1

So what's particularly interesting is that I had to work on a Windows machine (I think v10) earlier, and had experienced a different problem there: A single test takes excessive time (12-20s) to run. There are a number of posts on that issue, similarly, but no fix worked. Any chance these are related problems?

[951565664]

I experience this problem when I use ../node_modules/.bin/jest to run, Loop execution does not stop，I try and add --env=node ,

[rhinodavid]

I just started experiencing the same issue and have been scratching my head trying to find a solution… and I’ve figured it out. __My root directory was in my Dropbox folder.__ Every time Dropbox sync’d a file (even upload, it appears), Jest detected a change and reran the test. Pausing Dropbox sync fixes this for me.

[Sergioamjr]

I was getting this error, just after create an app with create-reac-app. The project was in a folder sync with iCloud too. I've moved the project to the desktop folder and the problem stopped. Seems me that jest is watching some folder above and triggering the tests.

[DenisGorbachev]

Solved by

    "watchPathIgnorePatterns": [
      "<rootDir>/node_modules",
    ]

although I don't believe it to be the right solution.

[smazzoleni]

Solved in jest.config.js by

    roots: ['src']

The problem for me was due to files created by reporters, which trigger a new test run everytime the previous run created the report file.
Another solution was to ignore report files with watchPathIgnorePatterns

[rmanguinho]

What I did was add a console.log to the change event linked in that issue. Then you can see what file triggers the watcher

Can you provide an example of how to do this?

[r-mc2]

For me it was a bit of a combination of both 951565664's comment & DenisGorbachev's solution.

We start jest from within a script that imports Jest itself, so it pulls jest out of "/node_modules/.bin/jest". Not 100% why, but running jest out of "node_modules" seems to update at least one file over and over. So, when using --watchAll it'll loop 5+ times before finally settling.

However, we can't use 951565664's solution of --env=node (or "testEnvironment": "node" for the config JSON), as some of our tests require the virtual DOM provided by jsdom.
But, adding node_modules to the watchPathIgnorePatterns Denis mentioned fixed it.