tests/test-check-help.t

templatekw: add new-style template expansion to {manifest}

The goal is to allow us to easily access to nested data. The dot operator
will be introduced later so we can write '{p1.files}' instead of
'{revset("p1()") % "{files}"}' for example.

In the example above, 'p1' needs to carry a mapping dict along with its
string representation. If it were a list or a dict, it could be wrapped
semi-transparently with the _hybrid class, but for non-list/dict types,
it would be difficult to proxy all necessary functions to underlying value
type because several core operations may conflict with the ones of the
underlying value:

 - hash(value) should be different from hash(wrapped(value)), which means
   dict[wrapped(value)] would be invalid
 - 'value == wrapped(value)' would be false, breaks 'ifcontains'
 - len(wrapped(value)) may be either len(value) or len(iter(wrapped(value)))

So the wrapper has no proxy functions and its scope designed to be minimal.
It's unwrapped at eval*() functions so we don't have to care for a wrapped
object unless it's really needed:

  # most template functions just call evalfuncarg()
  unwrapped_value = evalfuncarg(context, mapping, args[n])
  # if wrapped value is needed, use evalrawexp()
  maybe_wrapped_value = evalrawexp(context, mapping, args[n])

Another idea was to wrap every template variable with a tagging class, but
which seemed uneasy without a static type checker.

This patch updates {manifest} to a mappable as an example.

#require test-repo

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

  $ cat <<'EOF' > scanhelptopics.py
  > from __future__ import absolute_import, print_function
  > import re
  > import sys
  > if sys.platform == "win32":
  >     import os, msvcrt
  >     msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
  > topics = set()
  > topicre = re.compile(r':hg:`help ([a-z0-9\-.]+)`')
  > for fname in sys.argv:
  >     with open(fname) as f:
  >         topics.update(m.group(1) for m in topicre.finditer(f.read()))
  > for s in sorted(topics):
  >     print(s)
  > EOF

  $ cd "$TESTDIR"/..

Check if ":hg:`help TOPIC`" is valid:
(use "xargs -n1 -t" to see which help commands are executed)

  $ testrepohg files 'glob:{hgdemandimport,hgext,mercurial}/**/*.py' \
  > | sed 's|\\|/|g' \
  > | xargs $PYTHON "$TESTTMP/scanhelptopics.py" \
  > | xargs -n1 hg help > /dev/null