test-lfs: add tests demonstrating the interaction with largefiles

Obviously the original series needs to be accepted first, but there are concerns
about how well these extensions will play together before proceeding.  It looks
like the answer is surprisingly well.  There are some merge surprises
(largefiles seems to combine the choice of "keep tracking as a large/normal
file" with taking the content of the large/normal file) and some existing diff
weirdness (largefiles diffs the standins, not the large file).  Converting the
repo to normal files seemlessly transitions to lfs on the fly.  I didn't test
going the other way, because I'm not sure why anyone would want to do that.

I flagged the lack of a repo requirement after converting, because some of the
unsubmitted changes I have add a requirement on commit, but this somehow misses
the convert case.

I flagged an issue where devel-warnings are emitted on convert, which is a
separate issue.

tests/test-lfs-largefiles.t

@@ -0,0 +1,355
+This tests the interaction between the largefiles and lfs extensions, and
+conversion from largefiles -> lfs.
+
+  $ cat >> $HGRCPATH << EOF
+  > [extensions]
+  > largefiles =
+  > 
+  > [lfs]
+  > # standin files are 41 bytes.  Stay bigger for clarity.
+  > threshold = 42
+  > EOF
+
+Setup a repo with a normal file and a largefile, above and below the lfs
+threshold to test lfconvert.  *.txt start life as a normal file; *.bin start as
+an lfs/largefile.
+
+  $ hg init largefiles
+  $ cd largefiles
+  $ echo 'normal' > normal.txt
+  $ echo 'normal above lfs threshold 0000000000000000000000000' > lfs.txt
+  $ hg ci -Am 'normal.txt'
+  adding lfs.txt
+  adding normal.txt
+  $ echo 'largefile' > large.bin
+  $ echo 'largefile above lfs threshold 0000000000000000000000' > lfs.bin
+  $ hg add --large large.bin lfs.bin
+  $ hg ci -m 'add largefiles'
+
+  $ cat >> $HGRCPATH << EOF
+  > [extensions]
+  > lfs =
+  > EOF
+
+Add an lfs file and normal file that collide with files on the other branch.
+large.bin is added as a normal file, and is named as such only to clash with the
+largefile on the other branch.
+
+  $ hg up -q '.^'
+  $ echo 'below lfs threshold' > large.bin
+  $ echo 'lfs above the lfs threshold for length 0000000000000' > lfs.bin
+  $ hg ci -Am 'add with lfs extension'
+  adding large.bin
+  adding lfs.bin
+  created new head
+
+  $ hg log -G
+  @  changeset:   2:e989d0fa3764
+  |  tag:         tip
+  |  parent:      0:29361292f54d
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     add with lfs extension
+  |
+  | o  changeset:   1:6513aaab9ca0
+  |/   user:        test
+  |    date:        Thu Jan 01 00:00:00 1970 +0000
+  |    summary:     add largefiles
+  |
+  o  changeset:   0:29361292f54d
+     user:        test
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     summary:     normal.txt
+  
+--------------------------------------------------------------------------------
+Merge largefiles into lfs branch
+
+The largefiles extension will prompt to use the normal or largefile when merged
+into the lfs files.  `hg manifest` will show standins if present.  They aren't,
+because largefiles merge doesn't merge content.  If it did, selecting (n)ormal
+would convert to lfs on commit, if appropriate.
+
+BUG: Largefiles isn't running the merge tool, like when two lfs files are
+merged.  This is probably by design, but it should probably at least prompt if
+content should be taken from (l)ocal or (o)ther as well.
+
+  $ hg --config ui.interactive=True merge 6513aaab9ca0 <<EOF
+  > n
+  > n
+  > EOF
+  remote turned local normal file large.bin into a largefile
+  use (l)argefile or keep (n)ormal file? n
+  remote turned local normal file lfs.bin into a largefile
+  use (l)argefile or keep (n)ormal file? n
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg ci -m 'merge lfs with largefiles -> normal'
+  $ hg manifest
+  large.bin
+  lfs.bin
+  lfs.txt
+  normal.txt
+
+The merged lfs.bin resolved to lfs because the (n)ormal option was picked.  The
+lfs.txt file is unchanged by the merge, because it was added before lfs was
+enabled, and the content didn't change.
+  $ hg debugdata lfs.bin 0
+  version https://git-lfs.github.com/spec/v1
+  oid sha256:81c7492b2c05e130431f65a87651b54a30c5da72c99ce35a1e9b9872a807312b
+  size 53
+  x-is-binary 0
+  $ hg debugdata lfs.txt 0
+  normal above lfs threshold 0000000000000000000000000
+
+Another filelog entry is NOT made by the merge, so nothing is committed as lfs.
+  $ hg log -r . -T '{join(lfs_files, ", ")}\n'
+  
+
+Replay the last merge, but pick (l)arge this time.  The manifest will show any
+standins.
+
+  $ hg up -Cq e989d0fa3764
+
+  $ hg --config ui.interactive=True merge 6513aaab9ca0 <<EOF
+  > l
+  > l
+  > EOF
+  remote turned local normal file large.bin into a largefile
+  use (l)argefile or keep (n)ormal file? l
+  remote turned local normal file lfs.bin into a largefile
+  use (l)argefile or keep (n)ormal file? l
+  getting changed largefiles
+  2 largefiles updated, 0 removed
+  2 files updated, 0 files merged, 2 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg ci -m 'merge lfs with largefiles -> large'
+  created new head
+  $ hg manifest
+  .hglf/large.bin
+  .hglf/lfs.bin
+  lfs.txt
+  normal.txt
+
+--------------------------------------------------------------------------------
+Merge lfs into largefiles branch
+
+  $ hg up -Cq 6513aaab9ca0
+  $ hg --config ui.interactive=True merge e989d0fa3764 <<EOF
+  > n
+  > n
+  > EOF
+  remote turned local largefile large.bin into a normal file
+  keep (l)argefile or use (n)ormal file? n
+  remote turned local largefile lfs.bin into a normal file
+  keep (l)argefile or use (n)ormal file? n
+  getting changed largefiles
+  0 largefiles updated, 0 removed
+  2 files updated, 0 files merged, 2 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg ci -m 'merge largefiles with lfs -> normal'
+  created new head
+  $ hg manifest
+  large.bin
+  lfs.bin
+  lfs.txt
+  normal.txt
+
+The merged lfs.bin got converted to lfs because the (n)ormal option was picked.
+The lfs.txt file is unchanged by the merge, because it was added before lfs was
+enabled.
+  $ hg debugdata lfs.bin 0
+  version https://git-lfs.github.com/spec/v1
+  oid sha256:81c7492b2c05e130431f65a87651b54a30c5da72c99ce35a1e9b9872a807312b
+  size 53
+  x-is-binary 0
+  $ hg debugdata lfs.txt 0
+  normal above lfs threshold 0000000000000000000000000
+
+Another filelog entry is NOT made by the merge, so nothing is committed as lfs.
+  $ hg log -r . -T '{join(lfs_files, ", ")}\n'
+  
+
+Replay the last merge, but pick (l)arge this time.  The manifest will show the
+standins.
+
+  $ hg up -Cq 6513aaab9ca0
+
+  $ hg --config ui.interactive=True merge e989d0fa3764 <<EOF
+  > l
+  > l
+  > EOF
+  remote turned local largefile large.bin into a normal file
+  keep (l)argefile or use (n)ormal file? l
+  remote turned local largefile lfs.bin into a normal file
+  keep (l)argefile or use (n)ormal file? l
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg ci -m 'merge largefiles with lfs -> large'
+  created new head
+  $ hg manifest
+  .hglf/large.bin
+  .hglf/lfs.bin
+  lfs.txt
+  normal.txt
+
+--------------------------------------------------------------------------------
+
+When both largefiles and lfs are configured to add by size, the tie goes to
+largefiles since it hooks cmdutil.add() and lfs hooks the filelog write in the
+commit.  By the time the commit occurs, the tracked file is smaller than the
+threshold (assuming it is > 41, so the standins don't become lfs objects).
+
+  $ yes | head -n 1048576 > large_by_size.bin
+  $ hg --config largefiles.minsize=1 ci -Am 'large by size'
+  adding large_by_size.bin as a largefile
+  $ hg manifest
+  .hglf/large.bin
+  .hglf/large_by_size.bin
+  .hglf/lfs.bin
+  lfs.txt
+  normal.txt
+
+  $ hg rm large_by_size.bin
+  $ hg ci -m 'remove large_by_size.bin'
+
+Largefiles doesn't do anything special with diff, so it falls back to diffing
+the standins.  Extdiff also is standin based comparison.  Diff and extdiff both
+work on the original file for lfs objects.
+
+Largefile -> lfs transition
+  $ hg diff -r 1 -r 3
+  diff -r 6513aaab9ca0 -r dcc5ce63e252 .hglf/large.bin
+  --- a/.hglf/large.bin	Thu Jan 01 00:00:00 1970 +0000
+  +++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
+  @@ -1,1 +0,0 @@
+  -cef9a458373df9b0743a0d3c14d0c66fb19b8629
+  diff -r 6513aaab9ca0 -r dcc5ce63e252 .hglf/lfs.bin
+  --- a/.hglf/lfs.bin	Thu Jan 01 00:00:00 1970 +0000
+  +++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
+  @@ -1,1 +0,0 @@
+  -557fb6309cef935e1ac2c8296508379e4b15a6e6
+  diff -r 6513aaab9ca0 -r dcc5ce63e252 large.bin
+  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+  +++ b/large.bin	Thu Jan 01 00:00:00 1970 +0000
+  @@ -0,0 +1,1 @@
+  +below lfs threshold
+  diff -r 6513aaab9ca0 -r dcc5ce63e252 lfs.bin
+  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+  +++ b/lfs.bin	Thu Jan 01 00:00:00 1970 +0000
+  @@ -0,0 +1,1 @@
+  +lfs above the lfs threshold for length 0000000000000
+
+lfs -> largefiles transition
+  $ hg diff -r 2 -r 6
+  diff -r e989d0fa3764 -r 95e1e80325c8 .hglf/large.bin
+  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+  +++ b/.hglf/large.bin	Thu Jan 01 00:00:00 1970 +0000
+  @@ -0,0 +1,1 @@
+  +cef9a458373df9b0743a0d3c14d0c66fb19b8629
+  diff -r e989d0fa3764 -r 95e1e80325c8 .hglf/lfs.bin
+  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+  +++ b/.hglf/lfs.bin	Thu Jan 01 00:00:00 1970 +0000
+  @@ -0,0 +1,1 @@
+  +557fb6309cef935e1ac2c8296508379e4b15a6e6
+  diff -r e989d0fa3764 -r 95e1e80325c8 large.bin
+  --- a/large.bin	Thu Jan 01 00:00:00 1970 +0000
+  +++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
+  @@ -1,1 +0,0 @@
+  -below lfs threshold
+  diff -r e989d0fa3764 -r 95e1e80325c8 lfs.bin
+  --- a/lfs.bin	Thu Jan 01 00:00:00 1970 +0000
+  +++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
+  @@ -1,1 +0,0 @@
+  -lfs above the lfs threshold for length 0000000000000
+
+A largefiles repo can be converted to lfs.  The lfconvert command uses the
+convert extension under the hood with --to-normal.  So the --config based
+parameters are available, but not --authormap, --branchmap, etc.
+
+XXX: The default configitems are registered in convert.__init__, and I have no
+idea how to load that before lfconvert starts using other convert modules and
+incurring a devel-warn.  Even if the convert extension is enabled on the command
+line, it complains.  I have no idea how this fails, and the test in fcd2f9b06629
+works.
+
+  $ cd ..
+  $ hg lfconvert --to-normal largefiles nolargefiles 2>&1 | grep -v 'devel-warn'
+  initializing destination nolargefiles
+  0 additional largefiles cached
+  scanning source...
+  sorting...
+  converting...
+  8 normal.txt
+  7 add largefiles
+  6 add with lfs extension
+  5 merge lfs with largefiles -> normal
+  4 merge lfs with largefiles -> large
+  3 merge largefiles with lfs -> normal
+  2 merge largefiles with lfs -> large
+  1 large by size
+  0 remove large_by_size.bin
+  $ cd nolargefiles
+
+BUG: This should have a requires line for 'lfs'
+
+  $ cat .hg/requires
+  dotencode
+  fncache
+  generaldelta
+  revlogv1
+  store
+  $ hg log -r 'all()' -G -T '{rev} {join(lfs_files, ", ")} ({desc})\n'
+  o  8  (remove large_by_size.bin)
+  |
+  o  7 large_by_size.bin (large by size)
+  |
+  o    6  (merge largefiles with lfs -> large)
+  |\
+  +---o  5  (merge largefiles with lfs -> normal)
+  | |/
+  +---o  4 lfs.bin (merge lfs with largefiles -> large)
+  | |/
+  +---o  3  (merge lfs with largefiles -> normal)
+  | |/
+  | o  2 lfs.bin (add with lfs extension)
+  | |
+  o |  1 lfs.bin (add largefiles)
+  |/
+  o  0 lfs.txt (normal.txt)
+  
+  $ hg debugdata lfs.bin 0
+  version https://git-lfs.github.com/spec/v1
+  oid sha256:2172a5bd492dd41ec533b9bb695f7691b6351719407ac797f0ccad5348c81e62
+  size 53
+  x-is-binary 0
+  $ hg debugdata lfs.bin 1
+  version https://git-lfs.github.com/spec/v1
+  oid sha256:81c7492b2c05e130431f65a87651b54a30c5da72c99ce35a1e9b9872a807312b
+  size 53
+  x-is-binary 0
+  $ hg debugdata lfs.bin 2
+  version https://git-lfs.github.com/spec/v1
+  oid sha256:2172a5bd492dd41ec533b9bb695f7691b6351719407ac797f0ccad5348c81e62
+  size 53
+  x-is-binary 0
+  $ hg debugdata lfs.bin 3
+  abort: invalid revision identifier 3
+  [255]
+
+No diffs when comparing merge and p1 that kept p1's changes.  Diff of lfs to
+largefiles no longer operates in standin files.
+
+  $ hg diff -r 2:3
+  $ hg diff -r 2:6
+  diff -r e989d0fa3764 -r 752e3a0d8488 large.bin
+  --- a/large.bin	Thu Jan 01 00:00:00 1970 +0000
+  +++ b/large.bin	Thu Jan 01 00:00:00 1970 +0000
+  @@ -1,1 +1,1 @@
+  -below lfs threshold
+  +largefile
+  diff -r e989d0fa3764 -r 752e3a0d8488 lfs.bin
+  --- a/lfs.bin	Thu Jan 01 00:00:00 1970 +0000
+  +++ b/lfs.bin	Thu Jan 01 00:00:00 1970 +0000
+  @@ -1,1 +1,1 @@
+  -lfs above the lfs threshold for length 0000000000000
+  +largefile above lfs threshold 0000000000000000000000