hghave: allow adding customized features at runtime
Before this patch, there is no way to add customized features to
`hghave` without changing `hghave` and `hghave.py` themselves.
This decreases reusability of `run-tests.py` framework for third party
tools, because they may want to examine custom features at runtime
(e.g. existence of some external tools).
To allow adding customized features at runtime, this patch makes
`hghave` import `hghaveaddon` module, only when `hghaveaddon.py` file
can be found in directories below:
- `TESTDIR` for invocation via `run-tests.py`
- `.` for invocation via command line
The path to the directory where `hghaveaddon.py` should be placed is
added to `sys.path` only while importing `hghaveaddon`, because:
- `.` may not be added to `PYTHONPATH`
- adding additional path to `sys.path` may change behavior of
subsequent `import` for other features
`hghave` is terminated with exit code '2' at failure of `import
hghaveaddon`, because exit code '2' terminates `run-tests.py`
immediately.
This is a one of preparations for issue4677.
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 ..