Replace 2 occurrences of string in type ReactTestRendererJSON

[pedrottimark]

While studying implementation details of react-test-renderer, type ReactTestRendererJSON contradicted instead of confirmed what I had observed in Jest.

To verify misleading Flow errors, I temporarily pasted an object as if from renderer.create(<th colSpan={2}>{13}</th>).toJSON() into ReactTestRendererFiber.js and ReactTestRendererStack.js:

const th: ReactTestRendererJSON = {
  type: 'th',
  props: { colSpan: 2 },
  children: [13],
};

Currently the type is neither exported nor has an opportunity to report incorrect errors, but it could confuse people who read it as the specification of the object format from the test renderer.

• Is any too lax as the type for values of props?
• For the definition of ReactText see https://github.com/facebook/react/blob/master/src/renderers/shared/fiber/isomorphic/ReactTypes.js#L24

[gaearon]

@iamdustan Can you please review this?

[iamdustan]

I’m 90% certain this is okay, but want to confirm the possibly subtle differences between fiber and stack and the handling of numbers.

[iamdustan]

I have to double-check, but I don’t think the fiber version would ever return a number since it’s always converted to strings inside fiber.

[iamdustan]

yeah, I think this is okay. I thought the same thing when grabbing this from the stack implementation. 👍

[iamdustan]

since stack and children behave in slightly different ways I do think that numbers are still numbers at this point, but once again I’ll need to confirm in a short while.

[pedrottimark]

Thank you for reviewing. In case it helps you to understand what brought me here: test-rendering dom elements with only a relevant subset of props (given the purpose of that particular test) as the expected value for toMatchObject assertion. You might think of it as an “internal” snapshot whose goal is to minimize irrelevant changes to tests. So, I need to prototype in Fiber also, if possible :)

[pedrottimark]

I reverted to string in ReactTestRendererFiber.js because as @iamdustan suggested, the tests confirm a difference between Fiber and Stack reconciler:

• https://github.com/facebook/react/blob/master/src/renderers/testing/__tests__/ReactTestRenderer-test.js#L121
• https://github.com/facebook/react/blob/master/src/renderers/testing/__tests__/ReactTestRenderer-test.js#L498

[iamdustan]

I think this looks good @gaearon. Thanks @pedrottimark.