tests/test-empty-group.t

tests: add tests of pathcopies()

I'm working on support for storing copy metadata in the changeset
instead of in the filelog. When storing it in the changeset, it will
obviously be efficient to get the copy metadata for all files in a
single changeset, but it will be more expensive to get the copy
metadata all revisions of a single file. Some algorithms will then
need to be optimized differently. The first method I'm going to
rewrite is pathcopies().

This commit adds many tests for pathcopies(), so we can run the tests
with both old and new versions of the code, as well as with metadata
stored in filelog or in changeset (later). They use the
debugpathcopies command I recently added (with no tests when it was
added). They show a few bugs and few cases of slightly weird
behavior. I'll fix the bugs in the next few commits.

Differential Revision: https://phab.mercurial-scm.org/D5986

#  A          B
#
#  3  4       3
#  |\/|       |\
#  |/\|       | \
#  1  2       1  2
#  \ /        \ /
#   0          0
#
# if the result of the merge of 1 and 2
# is the same in 3 and 4, no new manifest
# will be created and the manifest group
# will be empty during the pull
#
# (plus we test a failure where outgoing
# wrongly reported the number of csets)

  $ hg init a
  $ cd a
  $ touch init
  $ hg ci -A -m 0
  adding init
  $ touch x y
  $ hg ci -A -m 1
  adding x
  adding y

  $ hg update 0
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ touch x y
  $ hg ci -A -m 2
  adding x
  adding y
  created new head

  $ hg merge 1
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -A -m m1

  $ hg update -C 1
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg merge 2
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -A -m m2
  created new head

  $ cd ..

  $ hg clone -r 3 a b
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 3 changes to 3 files
  new changesets 5fcb73622933:d15a0c284984
  updating to branch default
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg clone -r 4 a c
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 3 changes to 3 files
  new changesets 5fcb73622933:1ec3c74fc0e0
  updating to branch default
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg -R a outgoing b
  comparing with b
  searching for changes
  changeset:   4:1ec3c74fc0e0
  tag:         tip
  parent:      1:79f9e10cd04e
  parent:      2:8e1bb01c1a24
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     m2
  
  $ hg -R a outgoing c
  comparing with c
  searching for changes
  changeset:   3:d15a0c284984
  parent:      2:8e1bb01c1a24
  parent:      1:79f9e10cd04e
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     m1
  
  $ hg -R b outgoing c
  comparing with c
  searching for changes
  changeset:   3:d15a0c284984
  tag:         tip
  parent:      2:8e1bb01c1a24
  parent:      1:79f9e10cd04e
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     m1
  
  $ hg -R c outgoing b
  comparing with b
  searching for changes
  changeset:   3:1ec3c74fc0e0
  tag:         tip
  parent:      1:79f9e10cd04e
  parent:      2:8e1bb01c1a24
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     m2
  

  $ hg -R b pull a
  pulling from a
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 0 changes to 0 files (+1 heads)
  new changesets 1ec3c74fc0e0
  (run 'hg heads' to see heads, 'hg merge' to merge)

  $ hg -R c pull a
  pulling from a
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 0 changes to 0 files (+1 heads)
  new changesets d15a0c284984
  (run 'hg heads' to see heads, 'hg merge' to merge)