plugins/index.ts export should always be transpiled.

[sainthkh]

• Closes Typescript support: Update documentation for plugins.ts #7005

User facing changelog

When plugins/index.ts is not located at the default path and tsconfig.json has "module": "esnext" option, export is not transpiled. And it fails.

Additional details

Why was this change necessary?

To make TypeScript support available even when cypress tests are not located at the default path.

What is affected by this change?

N/A

Any implementation details to explain?

Added module: "CommonJS" to the option.

How has the user experience changed?

N/A

About test

Like #7072, this PR should also be tested on the master branch test repos. AFAIK, there is no way to test cypress open --project test/e2e command.

PR Tasks

• [N/A] Have tests been added/updated?
• Has the original issue been tagged with a release in ZenHub?
• [N/A] Has a PR for user-facing changes been opened in cypress-documentation?
• [N/A] Have API changes been updated in the type definitions?
• [N/A] Have new configuration options been added to the cypress.schema.json?

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User Experience

• The feature/bugfix is self-documenting from within the product.
• The change provides the end user with a way to fix their problem (no dead ends).

Functionality

• The code works and performs its intended function with the correct logic.
• Performance has been factored in (for example, the code cleans up after itself to not cause memory leaks).
• The code guards against edge cases and invalid input and has tests to cover it.

Maintainability

• The code is readable (too many nested 'if's are a bad sign).
• Names used for variables, methods, etc, clearly describe their function.
• The code is easy to understood and there are relevant comments explaining.
• New algorithms are documented in the code with link(s) to external docs (flowcharts, w3c, chrome, firefox).
• There are comments containing link(s) to the addressed issue (in tests and code).

Quality

• The change does not reimplement code.
• There's not a module from the ecosystem that should be used instead.
• There is no redundant or duplicate code.
• There are no irrelevant comments left in the code.
• Tests are testing the code’s intended functionality in the best way possible.

Internal

• The original issue has been tagged with a release in ZenHub.

[sainthkh]

this. is meaningless because it's an arrow function. It made projects load typescript from the cypress package, not their project.

[bahmutov]

yeah, between and project.js and resolve.js the duplication is hard to manage. Also, the tsnode options are better covered in #7166

[bahmutov]

I have confirmed that this PR finds the right user typescript module and transpiles the export keyword to always produce CommonJS module.

For testing, I suggest creating another fixture in packages/server/test/support/fixtures/projects and adding an e2e test in packages/server/test/e2e/3_plugins_spec.js

[sainthkh]

@bahmutov

I added a test that checks a project with tsconfig.json whose "module" value isn't "CommonJS".

This test makes me think:

• We can use the same test to test Make TypeScript always transpile modules to CommonJS style #7166. I guess we don't need other test for that PR.
• It doesn't test user typescript is imported correctly when the tests are executed with --project option.

[bahmutov]

Closing in favor of #7197