tests/test-hghave.t

largefiles: allow the archiving of largefiles to be disabled

There are currently no users of this, but it is a necessary step before
converting extdiff to use archive.  It may be useful to add an argument to
extdiff in the future and allow largefiles to be diffed, but archiving
largefiles can have significant overhead and may not be very diffable, so
archiving them by default seems wrong.

It is a mystery to me why the lfstatus attribute needs to be set on the
unfiltered repo.  However if it is set on the filtered repo instead (and the
filtered repo is passed to the original command), the lfstatus attribute is
False in the overrides for archival.archive() and hgsubrepo.archive() when
invoking the archive command.  This smells like the buggy status behavior (see
67d63ec85eb7, which was reverted in df463ca0adef).  Neither the status nor
summary commands have this weird behavior in their respective overrides.

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]