tests/test-extension-timing.t

rhg: Port Python’s `ui.configlist` as `Config::get_list`

This new method is not used yet outside of its own unit tests,
so this changeset should make no observable change.

The Rust parser implementation attempts to exactly replicate the behavior of
the Python one, even in edge cases where that behavior is… surprising.
New unit tests capture some of these edge cases.

This started as a line-by-line port. The main changes are:

* Pass around a parser mode enum instead of parser functions
* Inline the whole parser into one function
* Use `[u8]::get` which returns an `Option`,
  instead of indexing  after explicitly checking the length.

Differential Revision: https://phab.mercurial-scm.org/D11389

#require no-chg

Test basic extension support

  $ cat > foobar.py <<EOF
  > import os
  > from mercurial import commands, registrar
  > cmdtable = {}
  > command = registrar.command(cmdtable)
  > configtable = {}
  > configitem = registrar.configitem(configtable)
  > configitem(b'tests', b'foo', default=b"Foo")
  > def uisetup(ui):
  >     ui.debug(b"uisetup called [debug]\\n")
  >     ui.write(b"uisetup called\\n")
  >     ui.status(b"uisetup called [status]\\n")
  >     ui.flush()
  > def reposetup(ui, repo):
  >     ui.write(b"reposetup called for %s\\n" % os.path.basename(repo.root))
  >     ui.write(b"ui %s= repo.ui\\n" % (ui == repo.ui and b"=" or b"!"))
  >     ui.flush()
  > @command(b'foo', [], b'hg foo')
  > def foo(ui, *args, **kwargs):
  >     foo = ui.config(b'tests', b'foo')
  >     ui.write(foo)
  >     ui.write(b"\\n")
  > @command(b'bar', [], b'hg bar', norepo=True)
  > def bar(ui, *args, **kwargs):
  >     ui.write(b"Bar\\n")
  > EOF
  $ abspath=`pwd`/foobar.py

  $ mkdir barfoo
  $ cp foobar.py barfoo/__init__.py
  $ barfoopath=`pwd`/barfoo

  $ hg init a
  $ cd a
  $ echo foo > file
  $ hg add file
  $ hg commit -m 'add file'

  $ echo '[extensions]' >> $HGRCPATH
  $ echo "foobar = $abspath" >> $HGRCPATH

  $ filterlog () {
  >   sed -e 's!^[0-9/]* [0-9:]* ([0-9]*)>!YYYY/MM/DD HH:MM:SS (PID)>!'
  > }

Test extension setup timings

  $ hg foo --traceback --config devel.debug.extensions=yes --debug 2>&1 | filterlog
  YYYY/MM/DD HH:MM:SS (PID)> loading extensions
  YYYY/MM/DD HH:MM:SS (PID)> - processing 1 entries
  YYYY/MM/DD HH:MM:SS (PID)>   - loading extension: foobar
  YYYY/MM/DD HH:MM:SS (PID)>   > foobar extension loaded in * (glob)
  YYYY/MM/DD HH:MM:SS (PID)>     - validating extension tables: foobar
  YYYY/MM/DD HH:MM:SS (PID)>     - invoking registered callbacks: foobar
  YYYY/MM/DD HH:MM:SS (PID)>     > callbacks completed in * (glob)
  YYYY/MM/DD HH:MM:SS (PID)> > loaded 1 extensions, total time * (glob)
  YYYY/MM/DD HH:MM:SS (PID)> - loading configtable attributes
  YYYY/MM/DD HH:MM:SS (PID)> - executing uisetup hooks
  YYYY/MM/DD HH:MM:SS (PID)>   - running uisetup for foobar
  uisetup called [debug]
  uisetup called
  uisetup called [status]
  YYYY/MM/DD HH:MM:SS (PID)>   > uisetup for foobar took * (glob)
  YYYY/MM/DD HH:MM:SS (PID)> > all uisetup took * (glob)
  YYYY/MM/DD HH:MM:SS (PID)> - executing extsetup hooks
  YYYY/MM/DD HH:MM:SS (PID)>   - running extsetup for foobar
  YYYY/MM/DD HH:MM:SS (PID)>   > extsetup for foobar took * (glob)
  YYYY/MM/DD HH:MM:SS (PID)> > all extsetup took * (glob)
  YYYY/MM/DD HH:MM:SS (PID)> - executing remaining aftercallbacks
  YYYY/MM/DD HH:MM:SS (PID)> > remaining aftercallbacks completed in * (glob)
  YYYY/MM/DD HH:MM:SS (PID)> - loading extension registration objects
  YYYY/MM/DD HH:MM:SS (PID)> > extension registration object loading took * (glob)
  YYYY/MM/DD HH:MM:SS (PID)> > extension foobar take a total of * to load (glob)
  YYYY/MM/DD HH:MM:SS (PID)> extension loading complete
  YYYY/MM/DD HH:MM:SS (PID)> loading additional extensions
  YYYY/MM/DD HH:MM:SS (PID)> - processing 1 entries
  YYYY/MM/DD HH:MM:SS (PID)> > loaded 0 extensions, total time * (glob)
  YYYY/MM/DD HH:MM:SS (PID)> - loading configtable attributes
  YYYY/MM/DD HH:MM:SS (PID)> - executing uisetup hooks
  YYYY/MM/DD HH:MM:SS (PID)> > all uisetup took * (glob)
  YYYY/MM/DD HH:MM:SS (PID)> - executing extsetup hooks
  YYYY/MM/DD HH:MM:SS (PID)> > all extsetup took * (glob)
  YYYY/MM/DD HH:MM:SS (PID)> - executing remaining aftercallbacks
  YYYY/MM/DD HH:MM:SS (PID)> > remaining aftercallbacks completed in * (glob)
  YYYY/MM/DD HH:MM:SS (PID)> - loading extension registration objects
  YYYY/MM/DD HH:MM:SS (PID)> > extension registration object loading took * (glob)
  YYYY/MM/DD HH:MM:SS (PID)> extension loading complete
  YYYY/MM/DD HH:MM:SS (PID)> - executing reposetup hooks
  YYYY/MM/DD HH:MM:SS (PID)>   - running reposetup for foobar
  reposetup called for a
  ui == repo.ui
  YYYY/MM/DD HH:MM:SS (PID)>   > reposetup for foobar took * (glob)
  YYYY/MM/DD HH:MM:SS (PID)> > all reposetup took * (glob)
  Foo

  $ cd ..

  $ echo 'foobar = !' >> $HGRCPATH