Run load tests

Files named <name>.load.<ext> are load tests. The node presets recognize them but leave them out of a normal run, and always leave them out of coverage. This guide adds a second config that runs them.

Steps

Name the load test files <name>.load.<ext>, such as src/api.load.ts. Put them in the source folder with the other tests.
Create a second config that spreads configs.nodeLoad over your preset:
jest.load.config.mjs
```
import { configs } from '@repobuddy/jest'

export default {
  preset: '@repobuddy/jest/presets/ts-esm',
  ...configs.nodeLoad,
}
```
Your testRegex and coveragePathIgnorePatterns replace the preset’s.

Add a script:

{
  "scripts": {
    "test:load": "cross-env NODE_OPTIONS=--experimental-vm-modules jest --config jest.load.config.mjs"
  }
}

Drop NODE_OPTIONS for a CommonJS preset.

Run both kinds in one config

Pass both identifier lists to configs.configNode():

import { configs } from '@repobuddy/jest'

export default {
  preset: '@repobuddy/jest/presets/ts-esm',
  ...configs.configNode([...configs.defaultTestIdentifiers, ...configs.loadTestIdentifiers]),
}

Finished config

import { configs } from '@repobuddy/jest'

export default {
  preset: '@repobuddy/jest/presets/ts-esm',
  ...configs.nodeLoad,
}

Verify

Check that the normal run skips the load test:
Terminal window
```
jest --listTests
```
Check that the load config finds only load tests:
Terminal window
```
jest --config jest.load.config.mjs --listTests
```

In the ts-cjs fixture, the normal run lists 14 files and not nodejs.load.ts. A config of ts plus configs.nodeLoad lists only nodejs.load.ts.

Limits

Only the node presets have load test support. configs.jsdom has a fixed glob with no load identifier.
Load tests can also target a Node.js major: <name>.load.node20.ts.