tests/test-hghave.t

ui: move URL and path detection into path API

ui.expandpath() has code for recognizing URLs or local filesystem
paths. Our goal is to use ``path`` class instances everywhere a path
is represented.

Changing ui.expandpath() to return path instances is a lot of work.
Our goal is to slowly marginalize it by moving logic into the paths
API and to convert callers to the paths API.

Many callers of ui.expandpath() pass in a value that could be a
local filesystem path or URI. We move the detection of these strings
from ui.expandpath() to paths.getpath() and path.__init__(). To do
this properly in a way that is compatible with future callers, we
need to parse the "#branch" syntax out of locations. This is a bit
complicated, but it is necessary.

The code for URL parsing is essentially a copy of hg.parseurl().
Once all consumers are speaking the paths API, it is likely that
this function won't be called any more and it can be deleted.

Testing that hghave does not crash when checking features

  $ hghave --test-features 2>/dev/null

Testing hghave extensibility for third party tools

  $ cat > hghaveaddon.py <<EOF
  > import hghave
  > @hghave.check("custom", "custom hghave feature")
  > def has_custom():
  >     return True
  > EOF

(invocation via run-tests.py)

  $ cat > test-hghaveaddon.t <<EOF
  > #require custom
  >   $ echo foo
  >   foo
  > EOF
  $ run-tests.py test-hghaveaddon.t
  .
  # Ran 1 tests, 0 skipped, 0 warned, 0 failed.

(invocation via command line)

  $ unset TESTDIR
  $ hghave custom

(terminate with exit code 2 at failure of importing hghaveaddon.py)

  $ rm hghaveaddon.*
  $ cat > hghaveaddon.py <<EOF
  > importing this file should cause syntax error
  > EOF

  $ hghave custom
  failed to import hghaveaddon.py from '.': invalid syntax (hghaveaddon.py, line 1)
  [2]