view tests/test-pull-update.t @ 46706:93e9f448273c

rhg: Add support for automatic fallback to Python

`rhg` is a command-line application that can do a small subset of what
`hg` can. It is written entirely in Rust, which avoids the cost of starting
a Python interpreter and importing many Python modules.
In a script that runs many `hg` commands, this cost can add up.

However making users decide when to use `rhg` instead of `hg` is
not practical as we want the subset of supported functionality
to grow over time.

Instead we introduce "fallback" behavior where, when `rhg` encounters
something (a sub-command, a repository format, …) that is not implemented
in Rust-only, it does nothing but silently start a subprocess of
Python-based `hg` running the same command.
That way `rhg` becomes a drop-in replacement for `hg` that sometimes
goes faster. Whether Python is used should be an implementation detail
not apparent to users (other than through speed).

A new `fallback` value is added to the previously introduced
`rhg.on-unsupported` configuration key. When in this mode, the new
`rhg.fallback-executable` config is determine what command to use
to run a Python-based `hg`.

The previous `rhg.on-unsupported = abort-silent` configuration was designed
to let a wrapper script call `rhg` and then fall back to `hg` based on the
exit code. This is still available, but having fallback behavior built-in
in rhg might be easier for users instead of leaving that script "as an
exercise for the reader".

Using a subprocess like this is not idea, especially when `rhg` is to be
installed in `$PATH` as `hg`, since the other `hg.py` executable needs
to still be available… somewhere. Eventually this could be replaced
by using PyOxidizer to a have a single executable that embeds a Python
interpreter, but only starts it when needed.

Differential Revision: https://phab.mercurial-scm.org/D10093

  $ hg init t
  $ cd t
  $ echo 1 > foo
  $ hg ci -Am m
  adding foo

  $ cd ..
  $ hg clone t tt
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd tt
  $ echo 1.1 > foo
  $ hg ci -Am m

  $ cd ../t
  $ echo 1.2 > foo
  $ hg ci -Am m

Should respect config to disable dirty update
  $ hg co -qC 0
  $ echo 2 > foo
  $ hg --config commands.update.check=abort pull -u ../tt
  pulling from ../tt
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  new changesets 107cefe13e42
  1 local changesets published
  abort: uncommitted changes
  [20]
  $ hg --config extensions.strip= strip --no-backup tip
  $ hg co -qC tip

Should not update to the other topological branch:

  $ hg pull -u ../tt
  pulling from ../tt
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  new changesets 107cefe13e42
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  updated to "800c91d5bfc1: m"
  1 other heads for branch "default"

  $ cd ../tt

Should not update to the other branch:

  $ hg pull -u ../t
  pulling from ../t
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  new changesets 800c91d5bfc1
  1 local changesets published
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  updated to "107cefe13e42: m"
  1 other heads for branch "default"

  $ HGMERGE=true hg merge
  merging foo
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -mm

  $ cd ../t

Should work:

  $ hg pull -u ../tt
  pulling from ../tt
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (-1 heads)
  new changesets 483b76ad4309
  1 local changesets published
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

Similarity between "hg update" and "hg pull -u" in handling bookmark
====================================================================

Test that updating activates the bookmark, which matches with the
explicit destination of the update.

  $ echo 4 >> foo
  $ hg commit -m "#4"
  $ hg bookmark active-after-pull
  $ cd ../tt

(1) activating by --rev BOOKMARK

  $ hg bookmark -f active-before-pull
  $ hg bookmarks
   * active-before-pull        3:483b76ad4309

  $ hg pull -u -r active-after-pull
  pulling from $TESTTMP/t
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  adding remote bookmark active-after-pull
  added 1 changesets with 1 changes to 1 files
  new changesets f815b3da6163
  1 local changesets published
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (activating bookmark active-after-pull)

  $ hg parents -q
  4:f815b3da6163
  $ hg bookmarks
   * active-after-pull         4:f815b3da6163
     active-before-pull        3:483b76ad4309

(discard pulled changes)

  $ hg update -q 483b76ad4309
  $ hg rollback -q

(2) activating by URL#BOOKMARK

  $ hg bookmark -f active-before-pull
  $ hg bookmarks
   * active-before-pull        3:483b76ad4309

  $ hg pull -u $TESTTMP/t#active-after-pull
  pulling from $TESTTMP/t
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  adding remote bookmark active-after-pull
  added 1 changesets with 1 changes to 1 files
  new changesets f815b3da6163
  1 local changesets published
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (activating bookmark active-after-pull)

  $ hg parents -q
  4:f815b3da6163
  $ hg bookmarks
   * active-after-pull         4:f815b3da6163
     active-before-pull        3:483b76ad4309

(discard pulled changes)

  $ hg update -q 483b76ad4309
  $ hg rollback -q

Test that updating deactivates current active bookmark, if the
destination of the update is explicitly specified, and it doesn't
match with the name of any existing bookmarks.

  $ cd ../t
  $ hg bookmark -d active-after-pull
  $ hg branch bar -q
  $ hg commit -m "#5 (bar #1)"
  $ cd ../tt

(1) deactivating by --rev REV

  $ hg bookmark -f active-before-pull
  $ hg bookmarks
   * active-before-pull        3:483b76ad4309

  $ hg pull -u -r b5e4babfaaa7
  pulling from $TESTTMP/t
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 1 changes to 1 files
  new changesets f815b3da6163:b5e4babfaaa7
  1 local changesets published
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (leaving bookmark active-before-pull)

  $ hg parents -q
  5:b5e4babfaaa7
  $ hg bookmarks
     active-before-pull        3:483b76ad4309

(discard pulled changes)

  $ hg update -q 483b76ad4309
  $ hg rollback -q

(2) deactivating by --branch BRANCH

  $ hg bookmark -f active-before-pull
  $ hg bookmarks
   * active-before-pull        3:483b76ad4309

  $ hg pull -u -b bar
  pulling from $TESTTMP/t
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 1 changes to 1 files
  new changesets f815b3da6163:b5e4babfaaa7
  1 local changesets published
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (leaving bookmark active-before-pull)

  $ hg parents -q
  5:b5e4babfaaa7
  $ hg bookmarks
     active-before-pull        3:483b76ad4309

(discard pulled changes)

  $ hg update -q 483b76ad4309
  $ hg rollback -q

(3) deactivating by URL#ANOTHER-BRANCH

  $ hg bookmark -f active-before-pull
  $ hg bookmarks
   * active-before-pull        3:483b76ad4309

  $ hg pull -u $TESTTMP/t#bar
  pulling from $TESTTMP/t
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 1 changes to 1 files
  new changesets f815b3da6163:b5e4babfaaa7
  1 local changesets published
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (leaving bookmark active-before-pull)

  $ hg parents -q
  5:b5e4babfaaa7
  $ hg bookmarks
     active-before-pull        3:483b76ad4309

  $ cd ..