Does svelte-jester work with svelte 5?

[norricorp]

My package.json includes
"jest": "^29.7.0",
"svelte": "^5.0.0",
"svelte-jester": "^5.0.0",

For svelte 5 migration I added
import { render } from 'svelte/server';
to ssr.test.js

Result is

FAIL test/ssr/ssr.test.js
● Test suite failed to run

Jest encountered an unexpected token

Jest failed to parse a file. This happens e.g. when your code or its dependencies use non-standard JavaScript syntax, or when Jest is not configured to support such syntax.

Out of the box Jest supports Babel, which will be used to transform your files into valid JS based on your Babel configuration.

By default "node_modules" folder is ignored by transformers.

Here's what you can do:
 • If you are trying to use ECMAScript Modules, see https://jestjs.io/docs/ecmascript-modules for how to enable it.
 • If you are trying to use TypeScript, see https://jestjs.io/docs/getting-started#using-typescript
 • To have some of your "node_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config.
 • If you need a custom transformation specify a "transform" option in your config.
 • If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config option.

You'll find more details and examples of these config options in the docs:
https://jestjs.io/docs/configuration
For information about custom transformations, see:
https://jestjs.io/docs/code-transformation

Details:

C:\GitWork\svelte4-navigator\node_modules\svelte\src\server\index.js:1
({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,jest){export { render } from '../internal/server/index.js';
                                                                                  ^^^^^^

SyntaxError: Unexpected token 'export'

> 1 | import { render } from 'svelte/server';
    | ^
  2 | import cheerio from "cheerio";
  3 | // eslint-disable-next-line import/extensions, import/no-unresolved
  4 | import app from "./dist/App";

  at Runtime.createScriptFromCode (node_modules/jest-runtime/build/index.js:1505:14)
  at Object.require (test/ssr/ssr.test.js:1:1)

[sebastianrothe]

Thanks for the question. I might have some time on the weekend to look into this.

In the meantime, you can check here, if anything resolves the problem: #121 (comment)

[norricorp]

it certainly works with svelte 4. The tests, which were originally written for svelte 2/3, worked without any changes. But I did have to change the test code for 5 and that caused the error.

[norricorp]

Hi @sebastianrothe,
Did you get a chance to look at this?
Regards

[sebastianrothe]

Hi @sebastianrothe, Did you get a chance to look at this? Regards

Yeah, and to my surprise, we already have svelte5 support and tests. https://github.com/svelteness/svelte-jester/tree/master/e2e/svelte-5

I upgraded to the current svelte version and it works as well (#300). Can you provide a sample repo with your problem?

[norricorp]

The repo that I have been using is https://github.com/norricorp/svelte4-navigator on the svelte5 branch.
BUT https://github.com/norricorp/svelte4-navigator/blob/main/test/ssr/ssr.test.js does not contain the changed code, which is

import { render } from 'svelte/server';
import cheerio from "cheerio";
// eslint-disable-next-line import/extensions, import/no-unresolved
import app from "./dist/App";

const createSelector = testId => `[data-testid="${testId}"]`;

render = url => {
	const { html, head } = render(app, { props: { url }});
//	const { html } = app.render({ url });
	return testId => cheerio.load(html)(createSelector(testId));
};

I made the change based on
https://svelte.dev/docs/svelte/v5-migration-guide#Components-are-no-longer-classes-Server-API-changes

The error is pointing to the import render.

I will also raise this again with the svelte forum on discord. The background is that I made changes to a fork of the original repo and (naturally) wanted to do the minimum so I would rather not have to get involved with learning jest right now.