急にjest --watchができなくなったので、調べてみた。

現象

❯ yarn test:watch
yarn run v1.22.10
$ cross-env NODE_ENV=test jest --config=jest.config.json --watch
2021-03-23 20:35 node[59503] (FSEvents.framework) FSEventStreamStart: register_with_server: ERROR: f2d_register_rpc() => (null) (-22)
2021-03-23 20:35 node[59503] (FSEvents.framework) FSEventStreamStart: register_with_server: ERROR: f2d_register_rpc() => (null) (-22)
2021-03-23 20:35 node[59503] (FSEvents.framework) FSEventStreamStart: register_with_server: ERROR: f2d_register_rpc() => (null) (-22)
events.js:292
      throw er; // Unhandled 'error' event
      ^

Error: EMFILE: too many open files, watch
    at FSEvent.FSWatcher._handle.onchange (internal/fs/watchers.js:178:28)
Emitted 'error' event on FSWatcher instance at:
    at FSEvent.FSWatcher._handle.onchange (internal/fs/watchers.js:184:12) {
  errno: -24,
  syscall: 'watch',
  code: 'EMFILE',
  filename: null
}
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

環境

ProductName:    Mac OS X
ProductVersion: 10.13.6
BuildVersion:   17G14033

❯ node -v
v14.15.4
❯ yarn -v
1.22.10
❯ yarn jest --version
v20.0.4

最初はwatchmanはない。
yarnだとwatchmonがあるので間違いに注意。

❯ which watchman
watchman not found
❯ brew install watchman

長い更新時間

❯ which watchman
/usr/local/bin/watchman

実行結果

❯ yarn test:watch
yarn run v1.22.10
$ cross-env NODE_ENV=test jest --config=jest.config.json --watch

 PASS  src/tests/components/Header.test.js
 PASS  src/tests/components/ExpenseDashboardPage.test.js
 PASS  src/tests/components/AddExpensePage.test.js
 PASS  src/tests/actions/expenses.test.js
 PASS  src/tests/components/EditExpensePage.test.js
 PASS  src/tests/components/ConfModal.test.js
 PASS  src/tests/components/LoginPage.test.js
 PASS  src/tests/actions/auth.test.js

Test Suites: 8 passed, 8 total
Tests:       25 passed, 25 total
Snapshots:   6 passed, 6 total
Time:        7.874s, estimated 8s
Ran all test suites related to changed files.

✨  Done in 240.85s.

確かに実行できるようになった。

参考

JestのwatchがError watching file for changes: EMFILE でコケるときの対処
 macOS Sierra ＃1767でウォッチモードが機能しなくなりました