Make fc.pre an assertion function
#4709
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Sounds to be a really good idea. Thanks for the PR |
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By making `fc.pre` an assertion function TypeScript can narrow
types based on the condition. For example:
const item: number | undefined = numberArray[randomIndex]
fc.pre(item !== undefined)
item // narrowed type: number
If `fc.pre` is not an assertion function, we have to do an
additional (redundant) check to convince TypeScript that `item`
is not `undefined`.
See: https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-7.html#assertion-functions
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Everything is OK on my end. I'm just waiting a little bit to merge it. I have to decide how breaking it will be... In other words : Is it a minor or major? For now, I think so but I have to be sure. I promise you it's gonna merged soon either for next minor or for next major (currently working on packing everything for it). |
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no stress ❤️ |
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Will be available in a few minutes in 3.16.0 |
By making
fc.prean assertion function TypeScript can narrow types based on the condition. For example:If
fc.preis not an assertion function, we have to do an additional (redundant) check to convince TypeScript thatitemis notundefined.See: https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-7.html#assertion-functions
I marked this change as "decline" but I'm not sure what's appropriate. There is no runtime impact and the API hasn't really changed either. The return type is technically still
void.Category:
Potential impacts: