When I am developing a JavaScript module, I can use npm link to install my local development version in local projects that use the module as a dependency. This is a great workflow.
It's not developing in place, which I think is a less good than TDD, but its a way easier way to do integration testing and manual QA, I think.
In Composer, I can, if possible, force a package to install using git, so then I can develop in place. Nice, but not great.
Short version of question: Can I tell composer to temporarily install a dependency from a git repo/ set of files in my local file system and control the link from the composer CLI?