A new repository uses zlib storage, which doesn't need a requirement

  $ hg init default

  $ cd default

  $ cat .hg/requires

  dotencode

  fncache

  generaldelta

  revlogv1

  sparserevlog

  store

  testonly-simplestore (reposimplestore !)

  $ touch foo

  $ hg -q commit -A -m 'initial commit with a lot of repeated repeated repeated text to trigger compression'

  $ hg debugrevlog -c | grep 0x78

      0x78 (x)  :   1 (100.00%)

      0x78 (x)  : 110 (100.00%)

  $ cd ..

Unknown compression engine to format.compression aborts

  (run "hg debuginstall" to list available compression engines)

  [255]

A requirement specifying an unknown compression engine results in bail

  $ hg init unknownrequirement

  $ cd unknownrequirement

  $ echo exp-compression-unknown >> .hg/requires

  $ hg log

  abort: repository requires features unknown to this Mercurial: exp-compression-unknown!

  (see https://mercurial-scm.org/wiki/MissingRequirement for more information)

  [255]

  $ cd ..

#if zstd

  $ cd zstd

  $ cat .hg/requires

  dotencode

  exp-compression-zstd

  fncache

  generaldelta

  revlogv1

  sparserevlog

  store

  testonly-simplestore (reposimplestore !)

  $ touch foo

  $ hg -q commit -A -m 'initial commit with a lot of repeated repeated repeated text'

  $ hg debugrevlog -c | grep 0x28

      0x28      :  1 (100.00%)

      0x28      : 98 (100.00%)

  $ cd ..

Specifying a new format.compression on an existing repo won't introduce data

with that engine or a requirement

  $ cd default

  $ touch bar

  $ cat .hg/requires

  dotencode

  fncache

  generaldelta

  revlogv1

  sparserevlog

  store

  testonly-simplestore (reposimplestore !)

  $ hg debugrevlog -c | grep 0x78

      0x78 (x)  :   2 (100.00%)

      0x78 (x)  : 199 (100.00%)

#endif

checking zlib options

=====================

  $ hg init zlib-level-default

  $ hg init zlib-level-1

  $ cat << EOF >> zlib-level-1/.hg/hgrc

  > [storage]

  > revlog.zlib.level=1

  > EOF

  $ hg init zlib-level-9

  $ cat << EOF >> zlib-level-9/.hg/hgrc

  > [storage]

  > revlog.zlib.level=9

  > EOF

  $ commitone() {

  >    repo=$1

  >    cp $RUNTESTDIR/bundles/issue4438-r1.hg $repo/a

  >    hg -R $repo add $repo/a

  >    hg -R $repo commit -m some-commit

  > }

  $ for repo in zlib-level-default zlib-level-1 zlib-level-9; do

  >     commitone $repo

  > done

  $ $RUNTESTDIR/f -s */.hg/store/data/*

  zlib-level-1/.hg/store/data/a.i: size=4146

  zlib-level-9/.hg/store/data/a.i: size=4138

  zlib-level-default/.hg/store/data/a.i: size=4138

Test error cases

  $ hg init zlib-level-invalid

  $ cat << EOF >> zlib-level-invalid/.hg/hgrc

  > [storage]

  > revlog.zlib.level=foobar

  > EOF

  $ commitone zlib-level-invalid

  abort: storage.revlog.zlib.level is not a valid integer ('foobar')

  abort: storage.revlog.zlib.level is not a valid integer ('foobar')

  [255]

  $ hg init zlib-level-out-of-range

  $ cat << EOF >> zlib-level-out-of-range/.hg/hgrc

  > [storage]

  > revlog.zlib.level=42

  > EOF

  $ commitone zlib-level-out-of-range

  abort: invalid value for `storage.revlog.zlib.level` config: 42

  abort: invalid value for `storage.revlog.zlib.level` config: 42

  [255]

checking zstd options

=====================

  $ cat << EOF >> zstd-level-1/.hg/hgrc

  > [storage]

  > revlog.zstd.level=1

  > EOF

  $ cat << EOF >> zstd-level-22/.hg/hgrc

  > [storage]

  > revlog.zstd.level=22

  > EOF

  $ commitone() {

  >    repo=$1

  >    cp $RUNTESTDIR/bundles/issue4438-r1.hg $repo/a

  >    hg -R $repo add $repo/a

  >    hg -R $repo commit -m some-commit

  > }

  $ for repo in zstd-level-default zstd-level-1 zstd-level-22; do

  >     commitone $repo

  > done

  $ $RUNTESTDIR/f -s zstd-*/.hg/store/data/*

  zstd-level-1/.hg/store/data/a.i: size=4097

  zstd-level-22/.hg/store/data/a.i: size=4091

  zstd-level-default/.hg/store/data/a.i: size=4094

Test error cases

  $ cat << EOF >> zstd-level-invalid/.hg/hgrc

  > [storage]

  > revlog.zstd.level=foobar

  > EOF

  $ commitone zstd-level-invalid

  abort: storage.revlog.zstd.level is not a valid integer ('foobar')

  abort: storage.revlog.zstd.level is not a valid integer ('foobar')

  [255]

  $ cat << EOF >> zstd-level-out-of-range/.hg/hgrc

  > [storage]

  > revlog.zstd.level=42

  > EOF

  $ commitone zstd-level-out-of-range

  abort: invalid value for `storage.revlog.zstd.level` config: 42

  abort: invalid value for `storage.revlog.zstd.level` config: 42

  [255]