Add support to instanceOf for [Symbol.hasInstance] #1543
Merged
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Background
Though it is easy to replicate this functionality (eg:
sinon.match(x => s instanceof foo)
), the fact that this is not supported out-of-the-box can produce confusion, as the behaviour of instanceOf matchers and the instanceof operator differs regarding [Symbol.hasInstance].Solution
This PR addresses this issue by lifting the limitation to allow not only functions, but any object with [Symbol.hasInstance] method, as defined by the standard, if supported by the interpreter.
How to verify
npm install
node
(make sure your node version supports ES6 symbols)var sinon = require("./")
var matcher = sinon.match.instanceOf({ [Symbol.hasInstance]: () => true })
matcher.test("foo")
// returns trueChecklist for author
npm run lint
passes