tests/test-sidedata.t

tests: add test for Rust formatting

We enforce formatting for Python and C. It makes sense to do it
for Rust as well.

Since our rustfmt.toml relies on unstable rustfmt features, we
need to use a Nightly rustfmt with --unstable-features in order
for it to work. This is a bit hacky and I would prefer we remove
this requirement. But for now, this commit assumes this is the
way things must be and we go out of our way to detect and use the
rustfmt from the "nightly" toolchain, as installed via rustup.

We had to add some environment variables to the tests to make
the Rust binaries happy. Otherwise when running rustfmt we get
an error about no default toolchain being installed.

Differential Revision: https://phab.mercurial-scm.org/D7579

==========================================================
Test file dedicated to checking side-data related behavior
==========================================================

Check data can be written/read from sidedata
============================================

  $ cat << EOF >> $HGRCPATH
  > [extensions]
  > testsidedata=$TESTDIR/testlib/ext-sidedata.py
  > EOF

  $ hg init test-sidedata --config format.exp-use-side-data=yes
  $ cd test-sidedata
  $ echo aaa > a
  $ hg add a
  $ hg commit -m a --traceback
  $ echo aaa > b
  $ hg add b
  $ hg commit -m b
  $ echo xxx >> a
  $ hg commit -m aa

  $ hg debugsidedata -c 0
  2 sidedata entries
   entry-0001 size 4
   entry-0002 size 32
  $ hg debugsidedata -c 1 -v
  2 sidedata entries
   entry-0001 size 4
    '\x00\x00\x006'
   entry-0002 size 32
    '\x98\t\xf9\xc4v\xf0\xc5P\x90\xf7wRf\xe8\xe27e\xfc\xc1\x93\xa4\x96\xd0\x1d\x97\xaaG\x1d\xd7t\xfa\xde'
  $ hg debugsidedata -m 2
  2 sidedata entries
   entry-0001 size 4
   entry-0002 size 32
  $ hg debugsidedata a  1
  2 sidedata entries
   entry-0001 size 4
   entry-0002 size 32

Check upgrade behavior
======================

Right now, sidedata has not upgrade support

Check that we can upgrade to sidedata
-------------------------------------

  $ hg init up-no-side-data --config format.exp-use-side-data=no
  $ hg debugformat -v -R up-no-side-data
  format-variant    repo config default
  fncache:           yes    yes     yes
  dotencode:         yes    yes     yes
  generaldelta:      yes    yes     yes
  sparserevlog:      yes    yes     yes
  sidedata:           no     no      no
  copies-sdc:         no     no      no
  plain-cl-delta:    yes    yes     yes
  compression:       zlib   zlib    zlib
  compression-level: default default default
  $ hg debugformat -v -R up-no-side-data --config format.exp-use-side-data=yes
  format-variant    repo config default
  fncache:           yes    yes     yes
  dotencode:         yes    yes     yes
  generaldelta:      yes    yes     yes
  sparserevlog:      yes    yes     yes
  sidedata:           no    yes      no
  copies-sdc:         no     no      no
  plain-cl-delta:    yes    yes     yes
  compression:       zlib   zlib    zlib
  compression-level: default default default
  $ hg debugupgraderepo -R up-no-side-data --config format.exp-use-side-data=yes > /dev/null

Check that we can downgrade from sidedata
-----------------------------------------

  $ hg init up-side-data --config format.exp-use-side-data=yes
  $ hg debugformat -v -R up-side-data
  format-variant    repo config default
  fncache:           yes    yes     yes
  dotencode:         yes    yes     yes
  generaldelta:      yes    yes     yes
  sparserevlog:      yes    yes     yes
  sidedata:          yes     no      no
  copies-sdc:         no     no      no
  plain-cl-delta:    yes    yes     yes
  compression:       zlib   zlib    zlib
  compression-level: default default default
  $ hg debugformat -v -R up-side-data --config format.exp-use-side-data=no
  format-variant    repo config default
  fncache:           yes    yes     yes
  dotencode:         yes    yes     yes
  generaldelta:      yes    yes     yes
  sparserevlog:      yes    yes     yes
  sidedata:          yes     no      no
  copies-sdc:         no     no      no
  plain-cl-delta:    yes    yes     yes
  compression:       zlib   zlib    zlib
  compression-level: default default default
  $ hg debugupgraderepo -R up-side-data --config format.exp-use-side-data=no > /dev/null