Add a way to run pub and simulate 1+ packages are already published.

[kevmoo]

I'm hacking on package abc. I'm about ready to publish it.

I depend on abc from xyz.

I can put abc in the dependency_overrides section of xyz as a path dependency, but that misses things.

Did I mess up an SDK constraint? Another package constraint? etc etc

It'd be AWESOME if I could have the pub client simulate that a set of things I have locally are already published and then do it's thing.

cc @jakemac53 @natebosch

[kevmoo]

I'm trying to think of a way to do this without touching pubspec.yaml ... but it'd be nice to point to git repos as well. 🤷

[sigurdm]

This will be somewhat mitigated if/when we have staged publishing. You would be able to test out the package before fully publishing.

That said, I also think something like this would be really cool.
It would improve the workflow of mono-repos.

One issue is that we probably want to put this in a file somewhere. Flags are too ephemeral, eg. pub run will first check if the pubspec.lock is up-to-date, and without the flag it would not be able to confirm this.

See more discussions in this direction in: #2161 . Here we consider a separate override file. But I think the point of not overriding the solver completely, but rather treating the package as published in the solver is an important missing piece.