composer package development with dependencies

gistfile1.txt

develop your packages in a folder called, for example: packages/yourvendorname/packagename
push you package to git / packagist
after that, edit your main composer.json file so it will include you package (@section required)
now you autoloader knows about your package.
last but not least, the magic:

cd vendor/yourvendorname && rm -rf packagename && ln -s ../../packages/yourvendorname/packagename

now you can develop your package like it's in you live vendor directory.
so... now also you dependencies will load which you included in your 'required' section in your package composer.json