tests/test-encoding.t

tests: add test-remotefilelog-strip.t to demonstrate an issue with linknodes

### Background

Every time a commit is modified, remotefilelog updates the metadata for the file
object to point to the new commit (I believe that this is different from
non-remotefilelog hg, which leaves the linkrevs pointing to the obsolete
commits; doing otherwise would involve changing data in the middle of revlogs).

With `hg strip` (or other things that use repair.strip()), when you strip a
commit that's not the tip of the revlog, there may be commits after it in revnum
order that aren't descended from it and don't need to be (and shouldn't be)
stripped. These are "saved" by strip in a bundle, and that bundle is reapplied
after truncating the relevant revlogs.

### The problem

Remotefilelog generally avoids being involved at all in strip. Currently, that
includes even providing file contents to this backup bundle. This can cause the
linknode to point to a changeset that is no longer in the repository.

Example:

```
@  3 df91f74b871e
|
| x  2 70494d7ec5ef
|/
| x  1 1e423846dde0
|/
o  0 b292c1e3311f
```

Commits 1, 2, and 3 are related via obsolescence, and are description-only
changes. The linknode for the file in these commits changed each time we updated
the description, so it's currently df91f7. If I strip commits 1 and 3, however,
the linknode *remains* df91f7, which no longer exists in the repository. Commit
70494d was "saved", stripped, and then reapplied, so it is in the repository (as
revision 1 instead of 2 now), and was unobsoleted since the obsmarker was
stripped as well. The linknode for the file should point to 70494d, the most
recent commit that is in the repository that modified the file.

Remotefilelog has some logic to handle broken linknodes, but it can be slow. We
have actually disabled it internally because it's too slow for our purposes.

Differential Revision: https://phab.mercurial-scm.org/D10319

Test character encoding

  $ hg init t
  $ cd t

we need a repo with some legacy latin-1 changesets

  $ hg unbundle "$TESTDIR/bundles/legacy-encoding.hg"
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files
  new changesets 1e78a93102a3:0e5b7e3f9c4a (2 drafts)
  (run 'hg update' to get a working copy)
  $ hg co
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ "$PYTHON" << EOF
  > f = open('latin-1', 'wb'); f.write(b"latin-1 e' encoded: \xe9"); f.close()
  > f = open('utf-8', 'wb'); f.write(b"utf-8 e' encoded: \xc3\xa9"); f.close()
  > f = open('latin-1-tag', 'wb'); f.write(b"\xe9"); f.close()
  > EOF

should fail with encoding error

  $ echo "plain old ascii" > a
  $ hg st
  M a
  ? latin-1
  ? latin-1-tag
  ? utf-8
  $ HGENCODING=ascii hg ci -l latin-1
  transaction abort!
  rollback completed
  abort: decoding near ' encoded: \xe9': 'ascii' codec can't decode byte 0xe9 in position 20: ordinal not in range(128)! (esc)
  [255]

these should work

  $ echo "latin-1" > a
  $ HGENCODING=latin-1 hg ci -l latin-1
  $ echo "utf-8" > a
  $ HGENCODING=utf-8 hg ci -l utf-8
  $ HGENCODING=latin-1 hg tag `cat latin-1-tag`
  $ HGENCODING=latin-1 hg branch `cat latin-1-tag`
  marked working directory as branch \xe9 (esc)
  (branches are permanent and global, did you want a bookmark?)
  $ HGENCODING=latin-1 hg ci -m 'latin1 branch'
  $ hg -q rollback
  $ HGENCODING=latin-1 hg branch
  \xe9 (esc)
  $ HGENCODING=latin-1 hg ci -m 'latin1 branch'
  $ rm .hg/branch

hg log (ascii)

  $ hg --encoding ascii log
  changeset:   5:a52c0692f24a
  branch:      ?
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     latin1 branch
  
  changeset:   4:94db611b4196
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Added tag ? for changeset ca661e7520de
  
  changeset:   3:ca661e7520de
  tag:         ?
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     utf-8 e' encoded: ?
  
  changeset:   2:650c6f3d55dd
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     latin-1 e' encoded: ?
  
  changeset:   1:0e5b7e3f9c4a
  user:        test
  date:        Mon Jan 12 13:46:40 1970 +0000
  summary:     koi8-r: ????? = u'\u0440\u0442\u0443\u0442\u044c'
  
  changeset:   0:1e78a93102a3
  user:        test
  date:        Mon Jan 12 13:46:40 1970 +0000
  summary:     latin-1 e': ? = u'\xe9'
  

hg log (latin-1)

  $ hg --encoding latin-1 log
  changeset:   5:a52c0692f24a
  branch:      \xe9 (esc)
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     latin1 branch
  
  changeset:   4:94db611b4196
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Added tag \xe9 for changeset ca661e7520de (esc)
  
  changeset:   3:ca661e7520de
  tag:         \xe9 (esc)
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     utf-8 e' encoded: \xe9 (esc)
  
  changeset:   2:650c6f3d55dd
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     latin-1 e' encoded: \xe9 (esc)
  
  changeset:   1:0e5b7e3f9c4a
  user:        test
  date:        Mon Jan 12 13:46:40 1970 +0000
  summary:     koi8-r: \xd2\xd4\xd5\xd4\xd8 = u'\\u0440\\u0442\\u0443\\u0442\\u044c' (esc)
  
  changeset:   0:1e78a93102a3
  user:        test
  date:        Mon Jan 12 13:46:40 1970 +0000
  summary:     latin-1 e': \xe9 = u'\\xe9' (esc)
  

hg log (utf-8)

  $ hg --encoding utf-8 log
  changeset:   5:a52c0692f24a
  branch:      \xc3\xa9 (esc)
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     latin1 branch
  
  changeset:   4:94db611b4196
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Added tag \xc3\xa9 for changeset ca661e7520de (esc)
  
  changeset:   3:ca661e7520de
  tag:         \xc3\xa9 (esc)
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     utf-8 e' encoded: \xc3\xa9 (esc)
  
  changeset:   2:650c6f3d55dd
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     latin-1 e' encoded: \xc3\xa9 (esc)
  
  changeset:   1:0e5b7e3f9c4a
  user:        test
  date:        Mon Jan 12 13:46:40 1970 +0000
  summary:     koi8-r: \xc3\x92\xc3\x94\xc3\x95\xc3\x94\xc3\x98 = u'\\u0440\\u0442\\u0443\\u0442\\u044c' (esc)
  
  changeset:   0:1e78a93102a3
  user:        test
  date:        Mon Jan 12 13:46:40 1970 +0000
  summary:     latin-1 e': \xc3\xa9 = u'\\xe9' (esc)
  

hg tags (ascii)

  $ HGENCODING=ascii hg tags
  tip                                5:a52c0692f24a
  ?                                  3:ca661e7520de

hg tags (latin-1)

  $ HGENCODING=latin-1 hg tags
  tip                                5:a52c0692f24a
  \xe9                                  3:ca661e7520de (esc)

hg tags (utf-8)

  $ HGENCODING=utf-8 hg tags
  tip                                5:a52c0692f24a
  \xc3\xa9                                  3:ca661e7520de (esc)

hg tags (JSON)

  $ hg tags -Tjson
  [
   {
    "node": "a52c0692f24ad921c0a31e1736e7635a8b23b670",
    "rev": 5,
    "tag": "tip",
    "type": ""
   },
   {
    "node": "ca661e7520dec3f5438a63590c350bebadb04989",
    "rev": 3,
    "tag": "\xc3\xa9", (esc)
    "type": ""
   }
  ]

hg branches (ascii)

  $ HGENCODING=ascii hg branches
  ?                              5:a52c0692f24a
  default                        4:94db611b4196 (inactive)

hg branches (latin-1)

  $ HGENCODING=latin-1 hg branches
  \xe9                              5:a52c0692f24a (esc)
  default                        4:94db611b4196 (inactive)

hg branches (utf-8)

  $ HGENCODING=utf-8 hg branches
  \xc3\xa9                              5:a52c0692f24a (esc)
  default                        4:94db611b4196 (inactive)
  $ echo '[ui]' >> .hg/hgrc
  $ echo 'fallbackencoding = koi8-r' >> .hg/hgrc

hg log (utf-8)

  $ HGENCODING=utf-8 hg log
  changeset:   5:a52c0692f24a
  branch:      \xc3\xa9 (esc)
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     latin1 branch
  
  changeset:   4:94db611b4196
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Added tag \xc3\xa9 for changeset ca661e7520de (esc)
  
  changeset:   3:ca661e7520de
  tag:         \xc3\xa9 (esc)
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     utf-8 e' encoded: \xc3\xa9 (esc)
  
  changeset:   2:650c6f3d55dd
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     latin-1 e' encoded: \xc3\xa9 (esc)
  
  changeset:   1:0e5b7e3f9c4a
  user:        test
  date:        Mon Jan 12 13:46:40 1970 +0000
  summary:     koi8-r: \xd1\x80\xd1\x82\xd1\x83\xd1\x82\xd1\x8c = u'\\u0440\\u0442\\u0443\\u0442\\u044c' (esc)
  
  changeset:   0:1e78a93102a3
  user:        test
  date:        Mon Jan 12 13:46:40 1970 +0000
  summary:     latin-1 e': \xd0\x98 = u'\\xe9' (esc)
  

hg log (dolphin)

  $ HGENCODING=dolphin hg log
  abort: unknown encoding: dolphin
  (please check your locale settings)
  [255]
  $ HGENCODING=ascii hg branch `cat latin-1-tag`
  abort: decoding near '\xe9': 'ascii' codec can't decode byte 0xe9 in position 0: ordinal not in range(128)! (esc)
  [255]
  $ cp latin-1-tag .hg/branch
  $ HGENCODING=latin-1 hg ci -m 'auto-promote legacy name'

Test roundtrip encoding of lookup tables when not using UTF-8 (issue2763)

  $ HGENCODING=latin-1 hg up `cat latin-1-tag`
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ cd ..

Test roundtrip encoding/decoding of utf8b for generated data

#if hypothesis

  >>> import hypothesishelpers
  >>> from mercurial import encoding
  >>> hypothesishelpers.roundtrips(hypothesishelpers.st.binary(),
  ...                              encoding.fromutf8b, encoding.toutf8b)
  Round trip OK

#endif