tests/test-parseindex.t

import-checker: treat "from mercurial import XXXX" style correctly

Before this patch, "import-checker.py" assumes that the name of
Mercurial module recognized by "imported_modules" doesn't have package
part: for example, "util".

This is reason why "import-checker.py" always builds fully qualified
module name up relatively, if the given module doesn't belong to
standard Python library.

But in fact, modules imported in "from mercurial import XXXX" style
already have fully qualified name: for example, "mercurial.util"
module imported by "mercurial.parsers" is treated as
"mercurial.mercurial.util" because of building module name up
relatively.

This prevents "import-checker.py" from correctly checking about cyclic
dependency in them.

This patch avoids building module name up relatively, also if module
name starts with "mercurial.", to treat modules imported in "from
mercurial import XXXX" style correctly.

revlog.parseindex must be able to parse the index file even if
an index entry is split between two 64k blocks.  The ideal test
would be to create an index file with inline data where
64k < size < 64k + 64 (64k is the size of the read buffer, 64 is
the size of an index entry) and with an index entry starting right
before the 64k block boundary, and try to read it.
We approximate that by reducing the read buffer to 1 byte.

  $ hg init a
  $ cd a
  $ echo abc > foo
  $ hg add foo
  $ hg commit -m 'add foo'
  $ echo >> foo
  $ hg commit -m 'change foo'
  $ hg log -r 0:
  changeset:   0:7c31755bf9b5
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add foo
  
  changeset:   1:26333235a41c
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     change foo
  
  $ cat >> test.py << EOF
  > from mercurial import changelog, scmutil
  > from mercurial.node import *
  > 
  > class singlebyteread(object):
  >     def __init__(self, real):
  >         self.real = real
  > 
  >     def read(self, size=-1):
  >         if size == 65536:
  >             size = 1
  >         return self.real.read(size)
  > 
  >     def __getattr__(self, key):
  >         return getattr(self.real, key)
  > 
  > def opener(*args):
  >     o = scmutil.opener(*args)
  >     def wrapper(*a):
  >         f = o(*a)
  >         return singlebyteread(f)
  >     return wrapper
  > 
  > cl = changelog.changelog(opener('.hg/store'))
  > print len(cl), 'revisions:'
  > for r in cl:
  >     print short(cl.node(r))
  > EOF
  $ python test.py
  2 revisions:
  7c31755bf9b5
  26333235a41c

  $ cd ..