tests/test-hghave.t

color: respect HGPLAINEXCEPT=color to allow colors while scripting (issue5749)

I'd also like --color=always on the command-line to override HGPLAIN=1
et al, but that's more work, and this seems like a better fix. We've
got a fair number of programs that actually want to automate hg and
get colored output to users, so they should set HGPLAINEXCEPT=alias
(what we usually recommend), but this has been breaking them because
they then lose color.

.. feature::

  The ``HGPLAINEXCEPT`` environment variable can now include ``color``
  to allow automatic output colorization in otherwise automated
  environments.

Differential Revision: https://phab.mercurial-scm.org/D1532

  $ . "$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]