Jest doesn't work with Parcel out of the box, as the docs suggest

[provegard]

🐛 Bug Report

The Getting Started page states:

Jest can be used in projects that use parcel-bundler to manage assets, styles, and compilation similar to webpack. Parcel requires zero configuration. Refer to the official docs to get started.

This implies (to me) that Parcel can do preprocessing before Jest runs, and that I don't need to do anything to make it work. However, this does not seem to be the case. When I run Jest with some files that use import and export, I get:

    ({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,global,jest){import { jsSum } from "../src/js";
                                                                                             ^^^^^^

    SyntaxError: Cannot use import statement outside a module

Parcel can build the code without problem.

The linked Parcel documentation is not helpful AFAICS.

To Reproduce

1. Clone git@github.com:provegard/jest-test.git
2. Run npm install
3. Run npm test

Expected behavior

Jest uses Parcel to bundle/preprocess before running tests.

[ahnpnl]

I think Jest doc needs a guide like this https://jestjs.io/docs/webpack

[provegard]

I think Jest doc needs a guide like this https://jestjs.io/docs/webpack

Correct me if I'm wrong, but that guide doesn't seem to show how to use Webpack and Jest together, but rather how to translate Webpack config to Jest config, no?

[ahnpnl]

I’ve never tried that guide tbh. Perhaps you should ask in Jest Discord community to get help. This is not something provided out-of-the-box so I don’t think it is a Jest issue.

[provegard]

I'd say that the fact that Jest has documentation that is incorrect and/or misleading is a Jest issue.

In this particular case, the person who wrote the following supposedly meant to link to something useful:

Refer to the official docs to get started.

However, as far as I can tell the official Parcel docs are not useful when it comes to using Jest with Parcel, so I think one of two actions are appropriate:

1. Link to something useful.
2. Remove the unhelpful documentation.

Don't you agree?

[SimenB]

I've never used Parcel, so I'm not the person to update it. I think ideally we'd figure out what is needed and then update the guide. Would you be up for that?

I'm also happy to just remove it seeing as it's currently somewhat misleading.

#10211 (comment)

/cc @gkanishk

[gkanishk]

Hey @SimenB , I can work on documentation. We need to config babel along with parcel to work along with jest

[provegard]

Hey @SimenB , I can work on documentation. We need to config babel along with parcel to work along with jest

👍 I wouldn't know what to write anyway - I'm using parcel and jest and they both work fine, independently of each other.

[gkanishk]

Hey @SimenB , I can work on documentation. We need to config babel along with parcel to work along with jest

👍 I wouldn't know what to write anyway - I'm using parcel and jest and they both work fine, independently of each other.

will start working once I get assigned
cc. @SimenB

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