[BUG] Unknown file extension ".ts" on fresh init when adding "type": "module"

[pleek91]

Context:

• Playwright Version: 1.27.1
• Operating System: Mac
• Node.js version: 16.5.0
• Browser: N/A
• Extra: N/A

System:

• OS: macOS 12.6
• Memory: 89.59 MB / 16.00 GB

Binaries:

• Node: 16.5.0 - ~/.nvm/versions/node/v16.5.0/bin/node
• npm: 8.3.0 - ~/.nvm/versions/node/v16.5.0/bin/npm

Languages:

• Bash: 3.2.57 - /bin/bash

Code Snippet

N/A

Describe the bug

In a completely empty directory I ran npm init playwright@latest, and chose

✔ Do you want to use TypeScript or JavaScript? · TypeScript
✔ Where to put your end-to-end tests? · tests
✔ Add a GitHub Actions workflow? (y/N) · false
✔ Install Playwright browsers (can be done manually via 'npx playwright install')? (Y/n) · false

Then I ran npx playwright test and everything ran correctly.
Then I added "type": "module" to my package.json and ran npx playwright test again.

Received this error

TypeError: Unknown file extension ".ts" for /Users/my-name/Development/playwright-ts-bug/playwright.config.ts

[mxschmitt]

Works for me - I can't repro! Can you make sure that you use Node.js 16+? I saw you wrote that you are using a recent one, but type: module support is only supported in Playwright in 16+.

[pleek91]

My node version is 16.5.0 so that should be fine right?

[mxschmitt]

It actually needs to be a more recent one, like v16.18.0.

[pleek91]

Okay, I'll update node and try that again when I have a chance. Thank you! I'll close this issue.

[acdcjunior]

I got this error in a monorepo where the package with TS tests had "type": "module", and playwright was installed in the root.

Setting "type": "module", in the root as well fixed the problem.

I don't have non "type": "module", packages, so take it with a grain of salt.

[diegohaz]

I'm also seeing this error on a monorepo project. The packages with the test files are marked with "type": "module". But, unfortunately, I can't set "type": "module" to the root package, where the playwright.config.ts file is.

It would be nice if Playwright implemented a flag or something to force it to run as ESM even without "type": "module" or maybe detect it automatically by reading a playwright.config.mts file (notice the .mts extension).

The workaround I found was running playwright with an ESM loader (make sure to install esm-loader-typescript):

NODE_OPTIONS=--loader=esm-loader-typescript playwright test

[simonwep]

Any update on this one? This is still an issue... and I'm not sure what is the recommended workaround for that.

[M-51]

If you still have this problem, try to add playwright.config.ts file (if you don't have already) to directory where package.json of your project is.
I have no idea why it works this way.

I had simple project, I didn't need complex configuration, so I skipped config file (as far as I know it is not required), but was getting TypeError: Unknown file extension ".ts" error.

Then added empty playwright.config.ts - and it works...

If you have monorepo, every project needs to have own config file.
One playwright.config.ts in root of monorepo is not enough.

[morganney]

Why is this closed? At least update the documentation for install to include that a monorepo will require use of --config when running playwright test in case your config is colocated with the package containing tests.