tests/test-largefiles-cache.t

largefiles: cache new largefiles for new heads when pulling

When the user pulls from a remote repository that is not his default repo, it
is quite likely that he will pull a new head.  This means that if he tries to
merge or rebase with the other head, he will run into a problem becuase
largefiles has no way of tracking where the remote repository for this other
head is, so it cannot download the largefiles from this other remote repository.
It will attempt to download them from its default remote repository, which will
not yet contain the largefiles.

This patch solves this problem by caching any new largefiles for all heads
directly into the system cache at the time of the pull, so they are available
later.

This behavior is actually more in line with Mercurial's distributed nature,
because pulling already implies we have a connection to the remote server, but
merging or rebasing does not.

Create user cache directory

  $ USERCACHE=`pwd`/cache; export USERCACHE
  $ cat <<EOF >> ${HGRCPATH}
  > [extensions]
  > hgext.largefiles=
  > [largefiles]
  > usercache=${USERCACHE}
  > EOF
  $ mkdir -p ${USERCACHE}

Create source repo, and commit adding largefile.

  $ hg init src
  $ cd src
  $ echo large > large
  $ hg add --large large
  $ hg commit -m 'add largefile'
  $ cd ..

Discard all cached largefiles in USERCACHE

  $ rm -rf ${USERCACHE}

Create mirror repo, and pull from source without largefile:
"pull" is used instead of "clone" for suppression of (1) updating to
tip (= cahcing largefile from source repo), and (2) recording source
repo as "default" path in .hg/hgrc.

  $ hg init mirror
  $ cd mirror
  $ hg pull ../src
  pulling from ../src
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  (run 'hg update' to get a working copy)
  caching new largefiles
  0 largefiles cached

Update working directory to "tip", which requires largefile("large"),
but there is no cache file for it.  So, hg must treat it as
"missing"(!) file.

  $ hg update
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  getting changed largefiles
  large: Can't get file locally
  (no default or default-push path set in hgrc)
  0 largefiles updated, 0 removed
  $ hg status
  ! large

Update working directory to null: this cleanup .hg/largefiles/dirstate

  $ hg update null
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  getting changed largefiles
  0 largefiles updated, 0 removed

Update working directory to tip, again.

  $ hg update
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  getting changed largefiles
  large: Can't get file locally
  (no default or default-push path set in hgrc)
  0 largefiles updated, 0 removed
  $ hg status
  ! large