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docs: fix provider stateHandlers example #1513

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Jul 8, 2025
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docs: fix provider stateHandlers example #1513

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4 changes: 2 additions & 2 deletions docs/provider.md
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Original file line number Diff line number Diff line change
Expand Up @@ -120,9 +120,9 @@ If you have defined any `state`s in your consumer tests, the `Verifier` can put
const opts = {
...
stateHandlers: {
[null]: () => {
"null": () => {
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@mefellows mefellows Jun 26, 2025

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hmm this actually just matches the string "null", and not a null handler. Perhaps we're better updating the types to support this more directly?

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@zachlysobey zachlysobey Jun 26, 2025 •
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In JS, all object property keys (except for Symbols) are strings. When you use [null] like this, it coerces it to a string under the hood.

A few examples that demonstrate this

const obj = {};
obj[null] = 42;
console.log(obj); // { "null": 42 }
console.log(obj["null"]); // 42
Object.keys({ [null]: 1 }) // ['null']
Object.keys({ "null": 1 }) // ['null']
const obj1 = { [null]: 1, "null": 2 }
const obj2 = { "null": 2, [null]: 1 }
JSON.stringify(obj1) // '{"null":2}'
JSON.stringify(obj2) // '{"null":1}'

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@zachlysobey zachlysobey Jun 26, 2025 •
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All of those examples are how it works with the node REPL, or the browser console.
If you run those examples with ts-node (the TypeScript REPL) they all fail with runtime errors.
Compiling with tsc also fails for the same reason.

A computed property name must be of type 'string', 'number', 'symbol', or 'any'

This isn't a matter of updating the types or something. It's how TS was designed. They identify this pattern as confusing and problematic, and explicitly disallow it.

TS1170 has a bit more context

// This is the "default" state handler, when no state is given
}
},
"Has no animals": () => {
animalRepository.clear()
return Promise.resolve(`Animals removed from the db`)
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