fix(workers): use advanced serialization by default in child process workers

Author: SimenB

CHANGELOG.md

@@ -19,6 +19,7 @@
 - `[jest-runtime, jest-transform]` share `cacheFS` between runtime and transformer ([#10901](https://github.com/facebook/jest/pull/10901))
 - `[jest-transform]` Pass config options defined in Jest's config to transformer's `process` and `getCacheKey` functions ([#10926](https://github.com/facebook/jest/pull/10926))
 - `[jest-worker]` Add support for custom task queues and adds a `PriorityQueue` implementation. ([#10921](https://github.com/facebook/jest/pull/10921))
+- `[jest-worker]` [**BREAKING**] Default to advanced serialization when using child process workers ([#10982] (https://github.com/facebook/jest/pull/10982))
 
 ### Fixes
 

packages/jest-worker/README.md

@@ -69,7 +69,7 @@ Maximum amount of times that a dead child can be re-spawned, per call. Defaults
 
 #### `forkOptions: Object` (optional)
 
-Allow customizing all options passed to `childProcess.fork`. By default, some values are set (`cwd`, `env` and `execArgv`), but you can override them and customize the rest. For a list of valid values, check [the Node documentation](https://nodejs.org/api/child_process.html#child_process_child_process_fork_modulepath_args_options).
+Allow customizing all options passed to `childProcess.fork`. By default, some values are set (`cwd`, `env`, `execArgv` and `serialization`), but you can override them and customize the rest. For a list of valid values, check [the Node documentation](https://nodejs.org/api/child_process.html#child_process_child_process_fork_modulepath_args_options).
 
 #### `computeWorkerKey: (method: string, ...args: Array<any>) => ?string` (optional)
 

packages/jest-worker/src/workers/ChildProcessWorker.ts

@@ -92,6 +92,9 @@ export default class ChildProcessWorker implements WorkerInterface {
       } as NodeJS.ProcessEnv,
       // Suppress --debug / --inspect flags while preserving others (like --harmony).
       execArgv: process.execArgv.filter(v => !/^--(debug|inspect)/.test(v)),
+      // default to advanced serialization in order to match worker threads
+      // @ts-expect-error: option does not exist on the node 10 types
+      serialization: 'advanced',
       silent: true,
       ...this._options.forkOptions,
     });

packages/jest-worker/src/workers/__tests__/ChildProcessWorker.test.js

@@ -70,6 +70,7 @@ it('passes fork options down to child_process.fork, adding the defaults', () =>
     env: {...process.env, FORCE_COLOR: supportsColor.stdout ? '1' : undefined}, // Default option.
     execArgv: ['-p'], // Filtered option.
     execPath: 'hello', // Added option.
+    serialization: 'advanced', // Default option.
     silent: true, // Default option.
   });
 });