tests/test-children.t

formatter: add helper to create a formatter optionally backed by file

To make things simple, openformatter() and maybereopen() have no support
for a plain object API. Callers must use the "with" statement.

Unlike cmdutil.makefileobj(), append mode ('ab') isn't supported by these
functions. This is because JSON output can't be simply concatenated. Perhaps
cmdutil.export() will have to build a {filename: [revs...]} map first and
write revs per file.

test children command

  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > children =
  > EOF

init
  $ hg init t
  $ cd t

no working directory
  $ hg children

setup
  $ echo 0 > file0
  $ hg ci -qAm 0 -d '0 0'

  $ echo 1 > file1
  $ hg ci -qAm 1 -d '1 0'

  $ echo 2 >> file0
  $ hg ci -qAm 2 -d '2 0'

  $ hg co null
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ echo 3 > file3
  $ hg ci -qAm 3 -d '3 0'

hg children at revision 3 (tip)
  $ hg children

  $ hg co null
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

hg children at nullrev (should be 0 and 3)
  $ hg children
  changeset:   0:4df8521a7374
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  changeset:   3:e2962852269d
  tag:         tip
  parent:      -1:000000000000
  user:        test
  date:        Thu Jan 01 00:00:03 1970 +0000
  summary:     3
  
  $ hg co 1
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved

hg children at revision 1 (should be 2)
  $ hg children
  changeset:   2:8f5eea5023c2
  user:        test
  date:        Thu Jan 01 00:00:02 1970 +0000
  summary:     2
  
  $ hg co 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

hg children at revision 2 (other head)
  $ hg children

  $ for i in null 0 1 2 3; do
  > echo "hg children -r $i"
  > hg children -r $i
  > done
  hg children -r null
  changeset:   0:4df8521a7374
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  changeset:   3:e2962852269d
  tag:         tip
  parent:      -1:000000000000
  user:        test
  date:        Thu Jan 01 00:00:03 1970 +0000
  summary:     3
  
  hg children -r 0
  changeset:   1:708c093edef0
  user:        test
  date:        Thu Jan 01 00:00:01 1970 +0000
  summary:     1
  
  hg children -r 1
  changeset:   2:8f5eea5023c2
  user:        test
  date:        Thu Jan 01 00:00:02 1970 +0000
  summary:     2
  
  hg children -r 2
  hg children -r 3

hg children -r 0 file0 (should be 2)
  $ hg children -r 0 file0
  changeset:   2:8f5eea5023c2
  user:        test
  date:        Thu Jan 01 00:00:02 1970 +0000
  summary:     2
  

hg children -r 1 file0 (should be 2)
  $ hg children -r 1 file0
  changeset:   2:8f5eea5023c2
  user:        test
  date:        Thu Jan 01 00:00:02 1970 +0000
  summary:     2
  

  $ hg co 0
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved

hg children file0 at revision 0 (should be 2)
  $ hg children file0
  changeset:   2:8f5eea5023c2
  user:        test
  date:        Thu Jan 01 00:00:02 1970 +0000
  summary:     2
  

should be compatible with templater (don't pass fctx to displayer)
  $ hg children file0 -Tdefault
  changeset:   2:8f5eea5023c2
  user:        test
  date:        Thu Jan 01 00:00:02 1970 +0000
  summary:     2
  

  $ cd ..