API Extractor generates an api.md file containing the public API for a package. @fluentui/react and related packages as well as @fluentui/web-components use API Extractor to ensure that API changes must be reviewed before being merged into master. (@fluentui/react-northstar and related packages do not use API Extractor as of writing.)
As part of a package's build process, the api-extractor task checks the package's public API with the package's auto-generated .api.md file.
If building locally, the API file will be updated automatically (in 7.0 and master). Be sure to commit the updates with your other changes!
In PR builds, the task will fail if it detects missing API file updates.
(Previously it was necessary to run a separate command yarn update-api to update the API files, but we decided to streamline this and do the update automatically as part of the build instead.)
See the API Documentation page.