tests/test-revlog-v2.t

interfaces: introduce and use a protocol class for the `mpatch` module

See f2832de2a46c for details when this was done for the `bdiff` module.

Two things worth pointing out-

  1) The `cffi` module "inherits" the `pure` implementation of `patchedsize()`
     because of its wildcard import.
  2) It's odd that the `mpatchError` lives in both `pure` and `cext` modules.

I initially thought to move the exception into the new class, and make the
existing class name an alias to the class in the new location, but the exception
is created in C code by the `cext` module, so that won't work.  I don't think a
protocol class is approriate, because there's nothing special about the class to
distinguish from any other `Exception`.  Fortunately, nobody is catching this
exception in core, so we can kick the can down the road.

#require reporevlogstore

A repo with unknown revlogv2 requirement string cannot be opened

  $ hg init invalidreq
  $ cd invalidreq
  $ echo exp-revlogv2.unknown >> .hg/requires
  $ hg log
  abort: repository requires features unknown to this Mercurial: exp-revlogv2.unknown
  (see https://mercurial-scm.org/wiki/MissingRequirement for more information)
  [255]
  $ cd ..

Can create and open repo with revlog v2 requirement

  $ cat >> $HGRCPATH << EOF
  > [experimental]
  > revlogv2 = enable-unstable-format-and-corrupt-my-data
  > EOF

  $ hg init new-repo
  $ cd new-repo
  $ hg debugrequires | grep revlogv2
  exp-revlogv2.2
  dirstate-v2 (dirstate-v2 !)

  $ hg log

Unknown flags to revlog are rejected

  >>> with open('.hg/store/00changelog.i', 'wb') as fh:
  ...     fh.write(b'\xff\x00\xde\xad') and None

  $ hg log
  abort: unknown flags (0xff00) in version 57005 revlog 00changelog
  [50]

  $ cd ..

Writing a simple revlog v2 works

  $ hg init simple
  $ cd simple
  $ touch foo
  $ hg -q commit -A -m initial

  $ hg log
  changeset:   0:96ee1d7354c4
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     initial
  

Header written as expected

  $ f --hexdump --bytes 4 .hg/store/00changelog.i
  .hg/store/00changelog.i:
  0000: 00 00 de ad                                     |....|

  $ f --hexdump --bytes 4 .hg/store/data/foo.i
  .hg/store/data/foo.i:
  0000: 00 00 de ad                                     |....|

Bundle use a compatible changegroup format
------------------------------------------

  $ hg bundle --all ../basic.hg
  1 changesets found
  $ hg debugbundle --spec ../basic.hg
  bzip2-v2

The expected files are generated
--------------------------------

We should have have:
- a docket
- a index file with a unique name
- a data file

  $ ls .hg/store/00changelog* .hg/store/00manifest*
  .hg/store/00changelog-1335303a.sda
  .hg/store/00changelog-6b8ab34b.idx
  .hg/store/00changelog-b875dfc5.dat
  .hg/store/00changelog.i
  .hg/store/00manifest-05a21d65.idx
  .hg/store/00manifest-43c37dde.dat
  .hg/store/00manifest-e2c9362a.sda
  .hg/store/00manifest.i

Local clone works
-----------------

  $ hg clone . ../cloned-repo
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg tip | tee ../tip-new
  changeset:   0:96ee1d7354c4
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     initial
  
  $ hg tip -R ../cloned-repo | tee ../tip-cloned
  changeset:   0:96ee1d7354c4
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     initial
  

The two repository should be identical, this diff MUST be empty

  $ cmp ../tip-new ../tip-cloned || diff -U8 ../tip-new ../tip-cloned


hg verify should be happy
-------------------------

  $ hg verify -q

  $ hg verify -R ../cloned-repo -q