bundle2: add ability to write to a file to the test

Next changesets are about improving debug output during bundling. We won't be
able to simply bundle to stdin in this case. The bundle2 stream would be
interleaved with debug output.

tests/test-bundle2.t

@@ -1,170 +1,186 b''
 
 Create an extension to test bundle2 API
 
   $ cat > bundle2.py << EOF
   > """A small extension to test bundle2 implementation
   > 
   > Current bundle2 implementation is far too limited to be used in any core
   > code. We still need to be able to test it while it grow up.
   > """
   > 
   > import sys
   > from mercurial import cmdutil
   > from mercurial import util
   > from mercurial import bundle2
   > cmdtable = {}
   > command = cmdutil.command(cmdtable)
   > 
   > @command('bundle2',
   >          [('', 'param', [], 'stream level parameter'),],
-  >          '')
-  > def cmdbundle2(ui, repo, **opts):
+  >          '[OUTPUTFILE]')
+  > def cmdbundle2(ui, repo, path=None, **opts):
   >     """write a bundle2 container on standard ouput"""
   >     bundler = bundle2.bundle20()
   >     for p in opts['param']:
   >         p = p.split('=', 1)
   >         try:
   >             bundler.addparam(*p)
   >         except ValueError, exc:
   >             raise util.Abort('%s' % exc)
   > 
+  >     if path is None:
+  >        file = sys.stdout
+  >     else:
+  >         file = open(path, 'w')
+  > 
   >     for chunk in bundler.getchunks():
-  >         ui.write(chunk)
+  >         file.write(chunk)
   > 
   > @command('unbundle2', [], '')
   > def cmdunbundle2(ui, repo):
   >     """read a bundle2 container from standard input"""
   >     unbundler = bundle2.unbundle20(sys.stdin)
   >     ui.write('options count: %i\n' % len(unbundler.params))
   >     for key in sorted(unbundler.params):
   >         ui.write('- %s\n' % key)
   >         value = unbundler.params[key]
   >         if value is not None:
   >             ui.write('    %s\n' % value)
   >     parts = list(unbundler)
   >     ui.write('parts count:   %i\n' % len(parts))
   > EOF
   $ cat >> $HGRCPATH << EOF
   > [extensions]
   > bundle2=$TESTTMP/bundle2.py
   > EOF
 
 The extension requires a repo (currently unused)
 
   $ hg init main
   $ cd main
   $ touch a
   $ hg add a
   $ hg commit -m 'a'
 
 
 Empty bundle
 =================
 
 - no option
 - no parts
 
 Test bundling
 
   $ hg bundle2
   HG20\x00\x00\x00\x00 (no-eol) (esc)
 
 Test unbundling
 
   $ hg bundle2 | hg unbundle2
   options count: 0
   parts count:   0
 
 Test old style bundle are detected and refused
 
   $ hg bundle --all ../bundle.hg
   1 changesets found
   $ hg unbundle2 < ../bundle.hg
   abort: unknown bundle version 10
   [255]
 
 Test parameters
 =================
 
 - some options
 - no parts
 
 advisory parameters, no value
 -------------------------------
 
 Simplest possible parameters form
 
 Test generation simple option
 
   $ hg bundle2 --param 'caution'
   HG20\x00\x07caution\x00\x00 (no-eol) (esc)
 
 Test unbundling
 
   $ hg bundle2 --param 'caution' | hg unbundle2
   options count: 1
   - caution
   parts count:   0
 
 Test generation multiple option
 
   $ hg bundle2 --param 'caution' --param 'meal'
   HG20\x00\x0ccaution meal\x00\x00 (no-eol) (esc)
 
 Test unbundling
 
   $ hg bundle2 --param 'caution' --param 'meal' | hg unbundle2
   options count: 2
   - caution
   - meal
   parts count:   0
 
 advisory parameters, with value
 -------------------------------
 
 Test generation
 
   $ hg bundle2 --param 'caution' --param 'meal=vegan' --param 'elephants'
   HG20\x00\x1ccaution meal=vegan elephants\x00\x00 (no-eol) (esc)
 
 Test unbundling
 
   $ hg bundle2 --param 'caution' --param 'meal=vegan' --param 'elephants' | hg unbundle2
   options count: 3
   - caution
   - elephants
   - meal
       vegan
   parts count:   0
 
 parameter with special char in value
 ---------------------------------------------------
 
 Test generation
 
   $ hg bundle2 --param 'e|! 7/=babar%#==tutu' --param simple
   HG20\x00)e%7C%21%207/=babar%25%23%3D%3Dtutu simple\x00\x00 (no-eol) (esc)
 
 Test unbundling
 
   $ hg bundle2 --param 'e|! 7/=babar%#==tutu' --param simple | hg unbundle2
   options count: 2
   - e|! 7/
       babar%#==tutu
   - simple
   parts count:   0
 
+Test debug output
+---------------------------------------------------
+(no debug output yet)
+
+  $ hg bundle2 --debug --param 'e|! 7/=babar%#==tutu' --param simple ../out.hg2
+
+file content is ok
+
+  $ cat ../out.hg2
+  HG20\x00)e%7C%21%207/=babar%25%23%3D%3Dtutu simple\x00\x00 (no-eol) (esc)
+
 Test buggy input
 ---------------------------------------------------
 
 empty parameter name
 
   $ hg bundle2 --param '' --quiet
   abort: empty parameter name
   [255]
 
 bad parameter name
 
   $ hg bundle2 --param 42babar
   abort: non letter first character: '42babar'
   [255]