Composer: How to reference local git repo's branch for development.

composer-notes.md

APP'S COMPOSER.JSON

....
"repositories": [
    { "type": "git", "url": "../email-library" }
],
"require": {
    "php": ">=5.6.4",
    "laravel/framework": "5.4.*",
    "laravel/tinker": "~1.0",
    "acme/php-email-library": "dev-test"
},
....

PACKAGE/LIBRARY FOLDER

(at relative path mentioned in "repositories" above)

Create a branch called test (not dev-test) and make your commits there, but don't need to push to a remote repo. Then you can run composer update from your app's folder, and it'll reference the latest commit from that branch.