tests/test-logexchange.t

wireproto: implement basic frame reading and processing

We just implemented support for writing frames. Now let's implement
support for reading them.

The bulk of the new code is for a class that maintains the state of
a server. Essentially, you construct an instance, feed frames to it,
and it tells you what you should do next. The design is inspired by
the "sans I/O" movement and the reactor pattern. We don't want to
perform I/O or any major blocking event during frame ingestion because
this arbitrarily limits ways that server pieces can be implemented.
For example, it makes it much harder to swap in an alternate
implementation based on asyncio or do crazy things like have requests
dispatch to other processes.

We do still implement readframe() which does I/O. But it is decoupled
from the server reactor. And important parsing of frame headers is
a standalone function. So I/O is only needed to obtain frame data.

Because testing server-side ingest is useful and difficult on running
servers, we create a new "debugreflect" endpoint that will echo back
to the client what was received and how it was interpreted. This could
be useful for a server admin, someone implementing a client. But
immediately, it is useful for testing: we're able to demonstrate that
frames are parsed correctly and turned into requests to run commands
without having to implement command dispatch on the server!

In addition, we implement Python level unit tests for the reactor.
This is vastly more efficient than sending requests to the
"debugreflect" endpoint and vastly more powerful for advanced
testing.

Differential Revision: https://phab.mercurial-scm.org/D2852

Testing the functionality to pull remotenames
=============================================

  $ cat >> $HGRCPATH << EOF
  > [alias]
  > glog = log -G -T '{rev}:{node|short}  {desc}'
  > [experimental]
  > remotenames = True
  > [extensions]
  > remotenames =
  > show =
  > EOF

Making a server repo
--------------------

  $ hg init server
  $ cd server
  $ for ch in a b c d e f g h; do
  >   echo "foo" >> $ch
  >   hg ci -Aqm "Added "$ch
  > done
  $ hg glog
  @  7:ec2426147f0e  Added h
  |
  o  6:87d6d6676308  Added g
  |
  o  5:825660c69f0c  Added f
  |
  o  4:aa98ab95a928  Added e
  |
  o  3:62615734edd5  Added d
  |
  o  2:28ad74487de9  Added c
  |
  o  1:29becc82797a  Added b
  |
  o  0:18d04c59bb5d  Added a
  
  $ hg bookmark -r 3 foo
  $ hg bookmark -r 6 bar
  $ hg up 4
  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
  $ hg branch wat
  marked working directory as branch wat
  (branches are permanent and global, did you want a bookmark?)
  $ echo foo >> bar
  $ hg ci -Aqm "added bar"

Making a client repo
--------------------

  $ cd ..

  $ hg clone server client
  updating to branch default
  8 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ cd client
  $ cat .hg/logexchange/bookmarks
  0
  
  87d6d66763085b629e6d7ed56778c79827273022\x00default\x00bar (esc)
  62615734edd52f06b6fb9c2beb429e4fe30d57b8\x00default\x00foo (esc)

  $ cat .hg/logexchange/branches
  0
  
  ec2426147f0e39dbc9cef599b066be6035ce691d\x00default\x00default (esc)
  3e1487808078543b0af6d10dadf5d46943578db0\x00default\x00wat (esc)

  $ hg show work
  o  3e14 (wat) (default/wat) added bar
  |
  ~
  @  ec24 (default/default) Added h
  |
  ~

  $ hg update "default/wat"
  1 files updated, 0 files merged, 3 files removed, 0 files unresolved
  $ hg identify
  3e1487808078 (wat) tip

Making a new server
-------------------

  $ cd ..
  $ hg init server2
  $ cd server2
  $ hg pull ../server/
  pulling from ../server/
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 9 changesets with 9 changes to 9 files (+1 heads)
  adding remote bookmark bar
  adding remote bookmark foo
  new changesets 18d04c59bb5d:3e1487808078
  (run 'hg heads' to see heads)

Pulling form the new server
---------------------------
  $ cd ../client/
  $ hg pull ../server2/
  pulling from ../server2/
  searching for changes
  no changes found
  $ cat .hg/logexchange/bookmarks
  0
  
  62615734edd52f06b6fb9c2beb429e4fe30d57b8\x00default\x00foo (esc)
  87d6d66763085b629e6d7ed56778c79827273022\x00default\x00bar (esc)
  87d6d66763085b629e6d7ed56778c79827273022\x00$TESTTMP/server2\x00bar (esc)
  62615734edd52f06b6fb9c2beb429e4fe30d57b8\x00$TESTTMP/server2\x00foo (esc)

  $ cat .hg/logexchange/branches
  0
  
  3e1487808078543b0af6d10dadf5d46943578db0\x00default\x00wat (esc)
  ec2426147f0e39dbc9cef599b066be6035ce691d\x00default\x00default (esc)
  ec2426147f0e39dbc9cef599b066be6035ce691d\x00$TESTTMP/server2\x00default (esc)
  3e1487808078543b0af6d10dadf5d46943578db0\x00$TESTTMP/server2\x00wat (esc)

  $ hg log -G
  @  changeset:   8:3e1487808078
  |  branch:      wat
  |  tag:         tip
  |  remote branch:  $TESTTMP/server2/wat
  |  remote branch:  default/wat
  |  parent:      4:aa98ab95a928
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     added bar
  |
  | o  changeset:   7:ec2426147f0e
  | |  remote branch:  $TESTTMP/server2/default
  | |  remote branch:  default/default
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     Added h
  | |
  | o  changeset:   6:87d6d6676308
  | |  bookmark:    bar
  | |  remote bookmark:  $TESTTMP/server2/bar
  | |  remote bookmark:  default/bar
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     Added g
  | |
  | o  changeset:   5:825660c69f0c
  |/   user:        test
  |    date:        Thu Jan 01 00:00:00 1970 +0000
  |    summary:     Added f
  |
  o  changeset:   4:aa98ab95a928
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     Added e
  |
  o  changeset:   3:62615734edd5
  |  bookmark:    foo
  |  remote bookmark:  $TESTTMP/server2/foo
  |  remote bookmark:  default/foo
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     Added d
  |
  o  changeset:   2:28ad74487de9
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     Added c
  |
  o  changeset:   1:29becc82797a
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     Added b
  |
  o  changeset:   0:18d04c59bb5d
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     Added a
  
Testing the templates provided by remotenames extension

`remotenames` keyword

  $ hg log -G -T "{rev}:{node|short} {remotenames}\n"
  @  8:3e1487808078 $TESTTMP/server2/wat default/wat
  |
  | o  7:ec2426147f0e $TESTTMP/server2/default default/default
  | |
  | o  6:87d6d6676308 $TESTTMP/server2/bar default/bar
  | |
  | o  5:825660c69f0c
  |/
  o  4:aa98ab95a928
  |
  o  3:62615734edd5 $TESTTMP/server2/foo default/foo
  |
  o  2:28ad74487de9
  |
  o  1:29becc82797a
  |
  o  0:18d04c59bb5d
  
`remotebookmarks` and `remotebranches` keywords

  $ hg log -G -T "{rev}:{node|short} [{remotebookmarks}] ({remotebranches})"
  @  8:3e1487808078 [] ($TESTTMP/server2/wat default/wat)
  |
  | o  7:ec2426147f0e [] ($TESTTMP/server2/default default/default)
  | |
  | o  6:87d6d6676308 [$TESTTMP/server2/bar default/bar] ()
  | |
  | o  5:825660c69f0c [] ()
  |/
  o  4:aa98ab95a928 [] ()
  |
  o  3:62615734edd5 [$TESTTMP/server2/foo default/foo] ()
  |
  o  2:28ad74487de9 [] ()
  |
  o  1:29becc82797a [] ()
  |
  o  0:18d04c59bb5d [] ()
  
Testing the revsets provided by remotenames extension

`remotenames` revset

  $ hg log -r "remotenames()" -GT "{rev}:{node|short} {remotenames}\n"
  @  8:3e1487808078 $TESTTMP/server2/wat default/wat
  :
  : o  7:ec2426147f0e $TESTTMP/server2/default default/default
  : |
  : o  6:87d6d6676308 $TESTTMP/server2/bar default/bar
  :/
  o  3:62615734edd5 $TESTTMP/server2/foo default/foo
  |
  ~

`remotebranches` revset

  $ hg log -r "remotebranches()" -GT "{rev}:{node|short} {remotenames}\n"
  @  8:3e1487808078 $TESTTMP/server2/wat default/wat
  |
  ~
  o  7:ec2426147f0e $TESTTMP/server2/default default/default
  |
  ~

`remotebookmarks` revset

  $ hg log -r "remotebookmarks()" -GT "{rev}:{node|short} {remotenames}\n"
  o  6:87d6d6676308 $TESTTMP/server2/bar default/bar
  :
  o  3:62615734edd5 $TESTTMP/server2/foo default/foo
  |
  ~