Reduce dependency count

Describe the feature you’d like:

Reduce the number of dependencies installed when installing dom-testing-library. The feature set of this package is fantastic for anyone writing tests against the DOM.

Being able to query against the DOM in the language of your users and using waitFor & other techniques to deal with asynchronous frameworks is really really nice.

Currently when I install this library I get

├─┬ @testing-library/dom@7.5.2
│ ├─┬ @babel/runtime@7.9.6
│ │ └── regenerator-runtime@0.13.5
│ ├─┬ aria-query@4.0.2
│ │ ├── @babel/runtime@7.9.6 deduped
│ │ └─┬ @babel/runtime-corejs3@7.9.6
│ │   ├── core-js-pure@3.6.5
│ │   └── regenerator-runtime@0.13.5 deduped
│ ├── dom-accessibility-api@0.4.3
│ └─┬ pretty-format@26.0.1
│   ├─┬ @jest/types@26.0.1
│   │ ├── @types/istanbul-lib-coverage@2.0.1
│   │ ├─┬ @types/istanbul-reports@1.1.1
│   │ │ ├── @types/istanbul-lib-coverage@2.0.1 deduped
│   │ │ └─┬ @types/istanbul-lib-report@3.0.0
│   │ │   └── @types/istanbul-lib-coverage@2.0.1 deduped
│   │ ├─┬ @types/yargs@15.0.4
│   │ │ └── @types/yargs-parser@15.0.0
│   │ └─┬ chalk@4.0.0
│   │   ├── ansi-styles@4.2.1 deduped
│   │   └─┬ supports-color@7.1.0
│   │     └── has-flag@4.0.0
│   ├── ansi-regex@5.0.0
│   ├─┬ ansi-styles@4.2.1
│   │ ├── @types/color-name@1.1.1
│   │ └─┬ color-convert@2.0.1
│   │   └── color-name@1.1.4 deduped
│   └── react-is@16.13.1

29 dependencies, from these it looks like only ( @testing-library/dom ; dom-accessibility-api ; aria-query ; pretty-format ; ansi-styles ; color-convert ; color-name ) are useful dependencies.

It would be great if installing this library only installed 3 dependencies and if it had 4 optional dependencies ( pretty-format & ansi-* make great optional dependencies )

Suggested implementation:

To reduce dependency count the following could be implemented

• Removing babel dependency
• Remove nested babel dependency from aria-query
• Make pretty-format an optional dependencies
• Remove @jest/types from pretty-format or replace pretty-format with a smaller library.

Describe alternatives you’ve considered:

🤷

Teachability, Documentation, Adoption, Migration Strategy:

Having an optional dependency does require teaching users that pretty-format can be installed to pretty print the errors and warnings generated by dom-testing-library.

Your tests will work fine as is but might not be as pretty when looking at the output of a test failure without having installed pretty-format

An optional dependency looks like

let prettyFormat
try {
  prettyFormat = require('pretty-format')
} catch (err) {
  console.warn('If you would like a pretty error; please npm install pretty-format')
}

/* ... */

// In the library itself; wrap every usage of `prettyFormat` in a ternary or if statement
console.log(prettyFormat ? prettyFormat(x) : x)

[kentcdodds]

Thanks for sharing your opinions @Raynos, but I think there’s a values misalignment here so I don’t expect this to go anywhere. Sorry.

[eps1lon]

As an alternative to an optional dependency we could vendor it.

So we would need to maintain it rather than the folks over at jest? That doesn’t sound like a solution to me.

I understand the general concern but I don’t agree with the extreme step to simply cut it. All of the listed dependencies (with the exception of dom-accessibility-api maybe) are maintained either by large orgs or long term OSS maintainers.

The security risk they pose seems to be on the same level as using testing-library itself. It sounds like there is some subtext here I’m not getting. Could you explain why pretty-format is such an issue for you?