Add warning about implicit dependency on react-addons-test-utils

[thatjessicakelly]

A warning like this should hopefully help with #225.

Not exactly sure what the text should say.

[lelandrichardson]

Hmm. This is a good idea. we should do this for all of the implicit dependencies. We could link to the README of the repo for more context as well

[ljharb]

tbh this should probably process.exit(1) rather than rethrowing the error

[lelandrichardson]

I think error is better. Enzyme can be run in browser-based test runners

[ljharb]

ah, very true, this is fine then

[ljharb]

How many other implicit non-peer deps are there?? ideally we have as close to zero as possible

[lelandrichardson]

We are in this situation because of 0.13 and 0.14 compatibility...

If you are using React 0.13, then you are all good. react is all you need, and react is a dep.
If you are using React 0.14, then you need to have react, react-dom, and react-addons-test-utils.

Since react-dom and react-addons-test-utils are packages that cannot be installed alongside react 0.13, we need to have implicit dependencies.

[ljharb]

I wonder if making them optionalDependencies would be any better - i'm not sure how that field interacts with npm

[lelandrichardson]

@ljharb optionalDependencies won't work. We tried that first, and shit blew up if you tried to use enzyme with 0.13

[ljharb]

ah right, i'd forgotten. in that case this try/require/catch pattern is probably the cleanest way forward - maybe we could put all of those in one file (either one group or one per weird-dep) that re-exports either the libs or undefined, and require that module where they're needed?

[thatjessicakelly]

Let me know how you want me to handle it and I'm happy to update this

[lelandrichardson]

@ljharb i feel like there is already enough misdirection with the react-compat file. This file is already dealing with the differences between 0.13 and 0.14, so putting this logic here I think is sane.

@thatjessicakelly, do you think you could just update your PR to do the same thing for react-dom in addition to react-addons-test-utils?

[ljharb]

Makes sense.

[thatjessicakelly]

Done. I also linked to the README

[capaj]

@thatjessicakelly you keep using that word "warning", yet you throw an error. Interesting.

[ljharb]

@capaj that tone is not appreciated. Conceptually it's a warning, so by a technical definition of English, it's correct. You will not do well playing the condescending pedantry game here.

[capaj]

condescending pedantry game here

ok 😀