I want to make sure the infrastructure is headed in the right direction overall before fixing unit tests

begins to provide for this

D19706 begins to provide for this. I'm just going to roll the rest of it into T13098 since most further changes are likely to be entangled.

The lint unit tests are significantly entangled with general lint infrastructure, so I'm now looking at making arc lint run again: I want to make sure the infrastructure is headed in the right direction overall before fixing unit tests, so we don't end up with a narrowly-scoped fix to the lint tests that needs to be rewritten once arc lint comes online. In particular, linters currently have their hands very deep in repository / working copy information. Although I think it is plausible that a linter may want access to this information (for example, we have a unit test method which reads configuration to render a link to the Phabricator install, which doesn't seem strictly bad), I think linters and unit tests should not require this information and we should not need to build an entire working copy to run a linter.

Now that arc unit runs, I'm going to try to make the test suite pass so that tests are a useful tool in moving forward. We currently have 162 test failures.

Here are some of the bigger ideas around arc unit:

In theory, arc unit is next on the docket so we can start getting test coverage, then Windows support. However, I suspect arc unit may unfurl into a lot of substeps.

For prompting, the major things I want to do are:

In D19697 I claimed my next plans were "Windows, signal handling, and prompts", but I think arc unit needs to work again before I can convincingly do the Windows stuff. So it looks like signal handling and prompts first.

Also, damn, I've used libphutil for so many things - ExecFuture and HTTPSFuture are just by far the best thing out there for async work.

Actually, we can go one step further than D19686, I think.

We have a general initialization order issue where a later config file may define a load/--library setting that includes a typed Setting/Config object for a setting value in an earlier file. So I think this needs to happen in several phases:

T11934 is not exactly adjacent here, but I suspect it feeds into some other incidental goals and may provide a workaround for some things which get removed.