dartdev tests have no way to use source versions of subprocesses

[jcollins-g]

Particularly for the end to end tests, there is no way to use the source version of subprocesses like analysis_server during testing. This increases friction for making changes involving both dartdev and subprocesses because you have to rebuild the SDK on each loop. Worse still, the tests won't alert you if you forgot to (or didn't know you had to) rebuild which can lead to wasted time trying to figure out why changes don't seem to apply.

There should be some setting (possibly via an environment variable) for the tests and possibly dartdev itself to use source versions of the various tools where possible to make this simpler.

[sigurdm]

Not having to recompile the sdk every time would be awesome.

But running from source is not that fast. We probably want some way of precompiling the analysis_server and other processes to a snapshot before testing (maybe similar to what we do in pub ).