tests/test-revlog-v2.t

revlogv2: simplify and clarify the processing of each entry

As we add more entries and some of them has non trivial processing it seems
useful to make the processing leaner and clearly separated to simplify futures
patches.

Differential Revision: https://phab.mercurial-scm.org/D10773

#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 empty-repo
  $ cd empty-repo
  $ cat .hg/requires
  dotencode
  exp-dirstate-v2 (dirstate-v2 !)
  exp-revlogv2.2
  fncache
  generaldelta
  persistent-nodemap (rust !)
  revlog-compression-zstd (zstd !)
  sparserevlog
  store

  $ 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                                     |....|

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-6b8ab34b.dat
  .hg/store/00changelog-88698448.idx
  .hg/store/00changelog.i
  .hg/store/00manifest-1335303a.dat
  .hg/store/00manifest-b875dfc5.idx
  .hg/store/00manifest.i