Added unit test that would have caught the recent error code transform regression

[bvaughn]

Added an automated test that would have caught the regression introduced with #11291 and fixed by #11350.

The new test verifies that this:

invariant(condition, 'This is not a real error message.');

Gets transformed to this:

!condition ? invariant(false, 'This is not a real error message.') : void 0;

Prior to #11291 it would not have been transformed (and so would have been slightly less efficient). After #11291 (with the regression) it would have failed with:

+ !condition ? __DEV__ ? invariant(false, 'This is not a real error message.') : 'This is not a real error message.' : void 0;

[gaearon]

Tangential but one downside of more efficient code is now we exercise the argument calculation code path less in tests. Which means that if it throws with some unusual inputs we might not know now. Because we'll only get invariant when we test specifically for it failing.

On the other hand as far as I understand this was already happening as soon as a code was recorded anyway.

Perhaps we should make an exception for tests and never wrap for them at all?

[gaearon]

While we're at it let's rename the test to match the transform new name?

[bvaughn]

Perhaps we should make an exception for tests and never wrap for them at all?

In general, I dig this suggestion, but I'm not sure how we'd make it work with tests like ReactDOMProduction "should throw with an error code in production". The transform runs on the code before the tests beforeEach hook sets the fake NODE_ENV.

I think we'd actually need to run against the production build (eg react-dom.production.min) which sounds nicer than mocking NODE_ENV but I'm not sure how to accomplish it. Maybe we could circle back here as a follow up after chatting?

While we're at it let's rename the test to match the transform new name?

Sure.

[gaearon]

Sounds good.