tests/test-sparse-import.t

files: speed up `hg files` when no flags change display

It's not the first time I see slowness from this command slow down
tools built on top of hg.

The majority of the time is spent merely printing the result before
this change, which is clearly not how it should be (especially since
the computation of the result also looks slow).

Running `hg files` in mozilla-central:

parent revision: 1,260s
this commit: 0,683s
this commit without batching ui.write: 0,931s
this commit replacing the body of the loop with `pass`: 0,566s

This looks like a prime candidate for a rust fast path, but until
then, it seems reasonable to optimize the python.

Differential Revision: https://phab.mercurial-scm.org/D8586

test sparse

  $ hg init myrepo
  $ cd myrepo
  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > sparse=
  > purge=
  > strip=
  > rebase=
  > EOF

  $ echo a > index.html
  $ echo x > data.py
  $ echo z > readme.txt
  $ cat > base.sparse <<EOF
  > [include]
  > *.sparse
  > EOF
  $ hg ci -Aqm 'initial'
  $ cat > webpage.sparse <<EOF
  > %include base.sparse
  > [include]
  > *.html
  > EOF
  $ hg ci -Aqm 'initial'

Import a rules file against a 'blank' sparse profile

  $ cat > $TESTTMP/rules_to_import <<EOF
  > [include]
  > *.py
  > EOF
  $ hg debugsparse --import-rules $TESTTMP/rules_to_import
  $ ls -A
  .hg
  data.py

  $ hg debugsparse --reset
  $ rm .hg/sparse

  $ cat > $TESTTMP/rules_to_import <<EOF
  > %include base.sparse
  > [include]
  > *.py
  > EOF
  $ hg debugsparse --import-rules $TESTTMP/rules_to_import
  $ ls -A
  .hg
  base.sparse
  data.py
  webpage.sparse

  $ hg debugsparse --reset
  $ rm .hg/sparse

Start against an existing profile; rules *already active* should be ignored

  $ hg debugsparse --enable-profile webpage.sparse
  $ hg debugsparse --include *.py
  $ cat > $TESTTMP/rules_to_import <<EOF
  > %include base.sparse
  > [include]
  > *.html
  > *.txt
  > [exclude]
  > *.py
  > EOF
  $ hg debugsparse --import-rules $TESTTMP/rules_to_import
  $ ls -A
  .hg
  base.sparse
  index.html
  readme.txt
  webpage.sparse
  $ cat .hg/sparse
  %include webpage.sparse
  [include]
  *.py
  *.txt
  [exclude]
  *.py

  $ hg debugsparse --reset
  $ rm .hg/sparse

Same tests, with -Tjson enabled to output summaries

  $ cat > $TESTTMP/rules_to_import <<EOF
  > [include]
  > *.py
  > EOF
  $ hg debugsparse --import-rules $TESTTMP/rules_to_import -Tjson
  [
   {
    "exclude_rules_added": 0,
    "files_added": 0,
    "files_conflicting": 0,
    "files_dropped": 4,
    "include_rules_added": 1,
    "profiles_added": 0
   }
  ]

  $ hg debugsparse --reset
  $ rm .hg/sparse

  $ cat > $TESTTMP/rules_to_import <<EOF
  > %include base.sparse
  > [include]
  > *.py
  > EOF
  $ hg debugsparse --import-rules $TESTTMP/rules_to_import -Tjson
  [
   {
    "exclude_rules_added": 0,
    "files_added": 0,
    "files_conflicting": 0,
    "files_dropped": 2,
    "include_rules_added": 1,
    "profiles_added": 1
   }
  ]

  $ hg debugsparse --reset
  $ rm .hg/sparse

  $ hg debugsparse --enable-profile webpage.sparse
  $ hg debugsparse --include *.py
  $ cat > $TESTTMP/rules_to_import <<EOF
  > %include base.sparse
  > [include]
  > *.html
  > *.txt
  > [exclude]
  > *.py
  > EOF
  $ hg debugsparse --import-rules $TESTTMP/rules_to_import -Tjson
  [
   {
    "exclude_rules_added": 1,
    "files_added": 1,
    "files_conflicting": 0,
    "files_dropped": 1,
    "include_rules_added": 1,
    "profiles_added": 0
   }
  ]

If importing results in no new rules being added, no refresh should take place!

  $ cat > $TESTTMP/trap_sparse_refresh.py <<EOF
  > from mercurial import error, sparse
  > def extsetup(ui):
  >     def abort_refresh(*args, **kwargs):
  >         raise error.Abort('sparse._refresh called!')
  >     sparse.refreshwdir = abort_refresh
  > EOF
  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > trap_sparse_refresh=$TESTTMP/trap_sparse_refresh.py
  > EOF
  $ cat > $TESTTMP/rules_to_import <<EOF
  > [include]
  > *.py
  > EOF
  $ hg debugsparse --import-rules $TESTTMP/rules_to_import

If an exception is raised during refresh, restore the existing rules again.

  $ cat > $TESTTMP/rules_to_import <<EOF
  > [exclude]
  > *.html
  > EOF
  $ hg debugsparse --import-rules $TESTTMP/rules_to_import
  abort: sparse._refresh called!
  [255]
  $ cat .hg/sparse
  %include webpage.sparse
  [include]
  *.py
  *.txt
  [exclude]
  *.py