tests/test-hghave.t

test-lfs: add tests demonstrating the interaction with largefiles

Obviously the original series needs to be accepted first, but there are concerns
about how well these extensions will play together before proceeding.  It looks
like the answer is surprisingly well.  There are some merge surprises
(largefiles seems to combine the choice of "keep tracking as a large/normal
file" with taking the content of the large/normal file) and some existing diff
weirdness (largefiles diffs the standins, not the large file).  Converting the
repo to normal files seemlessly transitions to lfs on the fly.  I didn't test
going the other way, because I'm not sure why anyone would want to do that.

I flagged the lack of a repo requirement after converting, because some of the
unsubmitted changes I have add a requirement on commit, but this somehow misses
the convert case.

I flagged an issue where devel-warnings are emitted on convert, which is a
separate issue.

  $ . "$TESTDIR/helpers-testrepo.sh"

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
  $ ( \
  > testrepohgenv; \
  > $PYTHON $TESTDIR/run-tests.py $HGTEST_RUN_TESTS_PURE test-hghaveaddon.t \
  > )
  .
  # Ran 1 tests, 0 skipped, 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]