tests/test-show-work.t

show: use consistent (and possibly shorter) node lengths

`hg show` makes heavy use of shortest() to limit the length of the node
hash.

For the "stack" and "work" views, you are often looking at multiple
lines of similar output for "lines" of work. It is visually appeasing
for things to vertically align. A naive use of {shortest(node, N)}
could result in variable length nodes and for the first character of
the description to vary by a column or two.

We implement a function to determine the longest shortest prefix for
a set of revisions. The new function is used to determine the printed
node length for all `hg show` views.

.. feature::

   show: use consistent node length in views

Our previous shortest node length of 5 was arbitrarily chosen.

shortest() already does the work of ensuring that a partial node
isn't ambiguous with an integer revision, which is our primary risk
of a collision for very short nodes. It should be safe to go with the
shortest node possible.

Existing code is also optimized to handle nodes as short as 4.

So, we decrease the minimum hash length from 5 to 4.

We also add a test demonstrating that prefix collisions increase the
node length.

.. feature::

   show: decrease minimum displayed hash length from 5 to 4

Differential Revision: https://phab.mercurial-scm.org/D558

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

  $ hg init repo0
  $ cd repo0

Command works on an empty repo

  $ hg show work

Single draft changeset shown

  $ echo 0 > foo
  $ hg -q commit -A -m 'commit 0'

  $ hg show work
  @  9f17 commit 0

Even when it isn't the wdir

  $ hg -q up null

  $ hg show work
  o  9f17 commit 0

Single changeset is still there when public because it is a head

  $ hg phase --public -r 0
  $ hg show work
  o  9f17 commit 0

A draft child will show both it and public parent

  $ hg -q up 0
  $ echo 1 > foo
  $ hg commit -m 'commit 1'

  $ hg show work
  @  181c commit 1
  o  9f17 commit 0

Multiple draft children will be shown

  $ echo 2 > foo
  $ hg commit -m 'commit 2'

  $ hg show work
  @  128c commit 2
  o  181c commit 1
  o  9f17 commit 0

Bumping first draft changeset to public will hide its parent

  $ hg phase --public -r 1
  $ hg show work
  @  128c commit 2
  o  181c commit 1
  |
  ~

Multiple DAG heads will be shown

  $ hg -q up -r 1
  $ echo 3 > foo
  $ hg commit -m 'commit 3'
  created new head

  $ hg show work
  @  f0ab commit 3
  | o  128c commit 2
  |/
  o  181c commit 1
  |
  ~

Even when wdir is something else

  $ hg -q up null

  $ hg show work
  o  f0ab commit 3
  | o  128c commit 2
  |/
  o  181c commit 1
  |
  ~

Draft child shows public head (multiple heads)

  $ hg -q up 0
  $ echo 4 > foo
  $ hg commit -m 'commit 4'
  created new head

  $ hg show work
  @  668c commit 4
  | o  f0ab commit 3
  | | o  128c commit 2
  | |/
  | o  181c commit 1
  |/
  o  9f17 commit 0

  $ cd ..

Branch name appears in output

  $ hg init branches
  $ cd branches
  $ echo 0 > foo
  $ hg -q commit -A -m 'commit 0'
  $ echo 1 > foo
  $ hg commit -m 'commit 1'
  $ echo 2 > foo
  $ hg commit -m 'commit 2'
  $ hg phase --public -r .
  $ hg -q up -r 1
  $ hg branch mybranch
  marked working directory as branch mybranch
  (branches are permanent and global, did you want a bookmark?)
  $ echo 3 > foo
  $ hg commit -m 'commit 3'
  $ echo 4 > foo
  $ hg commit -m 'commit 4'

  $ hg show work
  @  f8dd (mybranch) commit 4
  o  90cf (mybranch) commit 3
  | o  128c commit 2
  |/
  o  181c commit 1
  |
  ~

  $ cd ..

Bookmark name appears in output

  $ hg init bookmarks
  $ cd bookmarks
  $ echo 0 > foo
  $ hg -q commit -A -m 'commit 0'
  $ echo 1 > foo
  $ hg commit -m 'commit 1'
  $ echo 2 > foo
  $ hg commit -m 'commit 2'
  $ hg phase --public -r .
  $ hg bookmark @
  $ hg -q up -r 1
  $ echo 3 > foo
  $ hg commit -m 'commit 3'
  created new head
  $ echo 4 > foo
  $ hg commit -m 'commit 4'
  $ hg bookmark mybook

  $ hg show work
  @  cac8 (mybook) commit 4
  o  f0ab commit 3
  | o  128c (@) commit 2
  |/
  o  181c commit 1
  |
  ~

  $ cd ..

Tags are rendered

  $ hg init tags
  $ cd tags
  $ echo 0 > foo
  $ hg -q commit -A -m 'commit 1'
  $ echo 1 > foo
  $ hg commit -m 'commit 2'
  $ hg tag 0.1
  $ hg phase --public -r .
  $ echo 2 > foo
  $ hg commit -m 'commit 3'
  $ hg tag 0.2

  $ hg show work
  @  3758 Added tag 0.2 for changeset 6379c25b76f1
  o  6379 (0.2) commit 3
  o  a2ad Added tag 0.1 for changeset 6a75536ea0b1
  |
  ~

  $ cd ..

Multiple names on same changeset render properly

  $ hg init multiplenames
  $ cd multiplenames
  $ echo 0 > foo
  $ hg -q commit -A -m 'commit 1'
  $ hg phase --public -r .
  $ hg branch mybranch
  marked working directory as branch mybranch
  (branches are permanent and global, did you want a bookmark?)
  $ hg bookmark mybook
  $ echo 1 > foo
  $ hg commit -m 'commit 2'

  $ hg show work
  @  3483 (mybook) (mybranch) commit 2
  o  97fc commit 1

Multiple bookmarks on same changeset render properly

  $ hg book mybook2
  $ hg show work
  @  3483 (mybook mybook2) (mybranch) commit 2
  o  97fc commit 1

  $ cd ..

Extra namespaces are rendered

  $ hg init extranamespaces
  $ cd extranamespaces
  $ echo 0 > foo
  $ hg -q commit -A -m 'commit 1'
  $ hg phase --public -r .
  $ echo 1 > foo
  $ hg commit -m 'commit 2'
  $ echo 2 > foo
  $ hg commit -m 'commit 3'

  $ hg --config extensions.revnames=$TESTDIR/revnamesext.py show work
  @  32f3 (r2) commit 3
  o  6a75 (r1) commit 2
  o  97fc (r0) commit 1

  $ cd ..

Prefix collision on hashes increases shortest node length

  $ hg init hashcollision
  $ cd hashcollision
  $ echo 0 > a
  $ hg -q commit -Am 0
  $ for i in 17 1057 2857 4025; do
  >   hg -q up 0
  >   echo $i > a
  >   hg -q commit -m $i
  >   echo 0 > a
  >   hg commit -m "$i commit 2"
  > done

  $ hg show work
  @  cfd04 4025 commit 2
  o  c562d 4025
  | o  08048 2857 commit 2
  | o  c5623 2857
  |/
  | o  6a6b6 1057 commit 2
  | o  c5625 1057
  |/
  | o  96b4e 17 commit 2
  | o  11424 17
  |/
  o  b4e73 0

  $ cd ..