tests/test-show.t

dirstate-tree: Avoid BTreeMap double-lookup when inserting a dirstate entry

The child nodes of a given node in the tree-shaped dirstate are kept in a
`BTreeMap` where keys are file names as strings. Finding or inserting a value
in the map takes `O(log(n))` string comparisons, which adds up when constructing
the tree.

The `entry` API allows finding a "spot" in the map that may or may not be
occupied and then access that value or insert a new one without doing map
lookup again. However the current API is limited in that calling `entry`
requires an owned key (and so a memory allocation), even if it ends up not
being used in the case where the map already has a value with an equal key.

This is still a win, with 4% better end-to-end time for `hg status` measured
here with hyperfine:

```
Benchmark #1: ../hg2/hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1
  Time (mean ± σ):      1.337 s ±  0.018 s    [User: 892.9 ms, System: 437.5 ms]
  Range (min … max):    1.316 s …  1.373 s    10 runs

Benchmark #2: ./hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1
  Time (mean ± σ):      1.291 s ±  0.008 s    [User: 853.4 ms, System: 431.1 ms]
  Range (min … max):    1.283 s …  1.309 s    10 runs

Summary
  './hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1' ran
    1.04 ± 0.02 times faster than '../hg2/hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1'
```

* ./hg is this revision
* ../hg2/hg is its parent
* $REPO is an old snapshot of mozilla-central

Differential Revision: https://phab.mercurial-scm.org/D10550

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

No arguments shows available views

  $ hg init empty
  $ cd empty
  $ hg show
  available views:
  
  bookmarks -- bookmarks and their associated changeset
  stack -- current line of work
  work -- changesets that aren't finished
  
  abort: no view requested
  (use "hg show VIEW" to choose a view)
  [255]

`hg help show` prints available views

  $ hg help show
  hg show VIEW
  
  show various repository information
  
      A requested view of repository data is displayed.
  
      If no view is requested, the list of available views is shown and the
      command aborts.
  
      Note:
         There are no backwards compatibility guarantees for the output of this
         command. Output may change in any future Mercurial release.
  
         Consumers wanting stable command output should specify a template via
         "-T/--template".
  
      List of available views:
  
      bookmarks   bookmarks and their associated changeset
  
      stack       current line of work
  
      work        changesets that aren't finished
  
  (use 'hg help -e show' to show help for the show extension)
  
  options:
  
   -T --template TEMPLATE display with template
  
  (some details hidden, use --verbose to show complete help)

Unknown view prints error

  $ hg show badview
  abort: unknown view: badview
  (run "hg show" to see available views)
  [255]

HGPLAIN results in abort

  $ HGPLAIN=1 hg show bookmarks
  abort: must specify a template in plain mode
  (invoke with -T/--template to control output format)
  [255]

But not if a template is specified

  $ HGPLAIN=1 hg show bookmarks -T '{bookmark}\n'
  (no bookmarks set)

  $ cd ..

bookmarks view with no bookmarks prints empty message

  $ hg init books
  $ cd books
  $ touch f0
  $ hg -q commit -A -m initial

  $ hg show bookmarks
  (no bookmarks set)

bookmarks view shows bookmarks in an aligned table

  $ echo book1 > f0
  $ hg commit -m 'commit for book1'
  $ echo book2 > f0
  $ hg commit -m 'commit for book2'

  $ hg bookmark -r 1 book1
  $ hg bookmark a-longer-bookmark

  $ hg show bookmarks
  * a-longer-bookmark    7b57
    book1                b757

A custom bookmarks template works

  $ hg show bookmarks -T '{node} {bookmark} {active}\n'
  7b5709ab64cbc34da9b4367b64afff47f2c4ee83 a-longer-bookmark True
  b757f780b8ffd71267c6ccb32e0882d9d32a8cc0 book1 False

bookmarks JSON works

  $ hg show bookmarks -T json
  [
   {
    "active": true,
    "bookmark": "a-longer-bookmark",
    "longestbookmarklen": 17,
    "node": "7b5709ab64cbc34da9b4367b64afff47f2c4ee83",
    "nodelen": 4
   },
   {
    "active": false,
    "bookmark": "book1",
    "longestbookmarklen": 17,
    "node": "b757f780b8ffd71267c6ccb32e0882d9d32a8cc0",
    "nodelen": 4
   }
  ]

JSON works with no bookmarks

  $ hg book -d a-longer-bookmark
  $ hg book -d book1
  $ hg show bookmarks -T json
  [
  ]

commands.show.aliasprefix aliases values to `show <view>`

  $ hg --config commands.show.aliasprefix=s sbookmarks
  (no bookmarks set)

  $ hg --config commands.show.aliasprefix=sh shwork
  @  7b57 commit for book2
  o  b757 commit for book1
  o  ba59 initial

  $ hg --config commands.show.aliasprefix='s sh' swork
  @  7b57 commit for book2
  o  b757 commit for book1
  o  ba59 initial

  $ hg --config commands.show.aliasprefix='s sh' shwork
  @  7b57 commit for book2
  o  b757 commit for book1
  o  ba59 initial

The aliases don't appear in `hg config`

  $ hg --config commands.show.aliasprefix=s config alias
  [1]

Doesn't overwrite existing alias

  $ hg --config alias.swork='log -r .' --config commands.show.aliasprefix=s swork
  changeset:   2:7b5709ab64cb
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     commit for book2
  

  $ hg --config alias.swork='log -r .' --config commands.show.aliasprefix=s config alias
  alias.swork=log -r .

  $ cd ..