view tests/test-update-names.t @ 33289:abd7dedbaa36

sparse: vendor Facebook-developed extension

Facebook has developed an extension to enable "sparse" checkouts -
a working directory with a subset of files. This feature is a critical
component in enabling repositories to scale to infinite number of
files while retaining reasonable performance. It's worth noting
that sparse checkout is only one possible solution to this problem:
another is virtual filesystems that realize files on first access.
But given that virtual filesystems may not be accessible to all
users, sparse checkout is necessary as a fallback.

Per mailing list discussion at
https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-March/095868.html
we want to add sparse checkout to the Mercurial distribution via
roughly the following mechanism:

1. Vendor extension as-is with minimal modifications (this patch)
2. Refactor extension so it is more clearly experimental and inline
   with Mercurial practices
3. Move code from extension into core where possible
4. Drop experimental labeling and/or move feature into core
   after sign-off from narrow clone feature owners

This commit essentially copies the sparse extension and tests
from revision 71e0a2aeca92a4078fe1b8c76e32c88ff1929737 of the
https://bitbucket.org/facebook/hg-experimental repository.

A list of modifications made as part of vendoring is as follows:

* "EXPERIMENTAL" added to module docstring
* Imports were changed to match Mercurial style conventions
* "testedwith" value was updated to core Mercurial special value and
  comment boilerplate was inserted
* A "clone_sparse" function was renamed to "clonesparse" to appease
  the style checker
* Paths to the sparse extension in tests reflect built-in location
* test-sparse-extensions.t was renamed to test-sparse-fsmonitor.t
  and references to "simplecache" were removed. The test always skips
  because it isn't trivial to run it given the way we currently run
  fsmonitor tests
* A double empty line was removed from test-sparse-profiles.t

There are aspects of the added code that are obviously not ideal.
The goal is to make a minimal number of modifications as part of
the vendoring to make it easier to track changes from the original
implementation. Refactoring will occur in subsequent patches.

Test update logic when there are renames or weird same-name cases between dirs
and files

Update with local changes across a file rename

  $ hg init r1 && cd r1

  $ echo a > a
  $ hg add a
  $ hg ci -m a

  $ hg mv a b
  $ hg ci -m rename

  $ echo b > b
  $ hg ci -m change

  $ hg up -q 0

  $ echo c > a

  $ hg up
  merging a and b to b
  warning: conflicts while merging b! (edit, then use 'hg resolve --mark')
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges
  [1]

Test update when local untracked directory exists with the same name as a
tracked file in a commit we are updating to
  $ hg init r2 && cd r2
  $ echo root > root && hg ci -Am root  # rev 0
  adding root
  $ echo text > name && hg ci -Am "name is a file"  # rev 1
  adding name
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ mkdir name
  $ hg up 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

Test update when local untracked directory exists with some files in it and has
the same name a tracked file in a commit we are updating to. In future this
should be updated to give an friendlier error message, but now we should just
make sure that this does not erase untracked data
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ mkdir name
  $ echo text > name/file
  $ hg st
  ? name/file
  $ hg up 1
  abort: *: '$TESTTMP/r1/r2/name' (glob)
  [255]
  $ cd ..

#if symlink

Test update when two commits have symlinks that point to different folders
  $ hg init r3 && cd r3
  $ echo root > root && hg ci -Am root
  adding root
  $ mkdir folder1 && mkdir folder2
  $ ln -s folder1 folder
  $ hg ci -Am "symlink to folder1"
  adding folder
  $ rm folder
  $ ln -s folder2 folder
  $ hg ci -Am "symlink to folder2"
  $ hg up 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd ..

#endif

#if rmcwd

Test that warning is printed if cwd is deleted during update
  $ hg init r4 && cd r4
  $ mkdir dir
  $ cd dir
  $ echo a > a
  $ echo b > b
  $ hg add a b
  $ hg ci -m "file and dir"
  $ hg up -q null
  current directory was removed
  (consider changing to repo root: $TESTTMP/r1/r4)

#endif