Using local version of a library instead of the one published to npm.

Say, you’re developing xml-wrappers. In local xml-wrappers directory

$ yarn link
...
info You can now run `yarn link "xml-wrappers"` in the projects where you want to use this package and it will be used instead.
...

Go to the application which uses the library

$ yarn link xml-wrappers
...
success Using linked package for "xml-wrappers".

Unlink after you’re done

$ yarn unlink