Sweden-Number/documentation/cvs-regression.sgml

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<chapter id="cvs-regression">
<title>How to do regression testing using Cvs</title>
<para>
written by (???)
</para>
<para>
(Extracted from <filename>wine/documentation/bugreports</filename>)
</para>
<para>
A problem that can happen sometimes is 'it used to work
before, now it doesn't anymore...'. Here is a step by step
procedure to try to pinpoint when the problem occured. This is
<emphasis>NOT</emphasis> for casual users.
</para>
<orderedlist>
<listitem>
<para>
Get the 'full cvs' archive from winehq. This archive is
the cvs tree but with the tags controlling the versioning
system. It's a big file (> 15 meg) with a name like
full-cvs-&lt;last update date> (it's more than 100mb
when uncompressed, you can't very well do this with
small, old computers or slow Internet connections).
</para>
</listitem>
<listitem>
<para>
untar it into a repository directory:
<screen>
cd /home/gerard
tar -zxffull-cvs-2000-05-20.tar.gz
mv wine repository
</screen>
</para>
</listitem>
<listitem>
<para>
extract a new destination directory. This directory must
not be in a subdirectory of the repository else
<command>cvs</command> will think it's part of the
repository and deny you an extraction in the repository:
<screen>
cd /home/gerard
mv wine wine_current (-> this protects your current wine sandbox, if any)
export CVSROOT=/home/gerard/repository
cd /home/gerard
cvs -d $CVSROOT checkout wine
</screen>
</para>
<para>
Note that it's not possible to do a checkout at a given
date; you always do the checkout for the last date where
the full-cvs-xxx snapshot was generated.
</para>
</listitem>
<listitem>
<para>
you will have now in the <filename>~/wine</filename>
directory an image of the cvs tree, on the client side.
Now update this image to the date you want:
<screen>
cd /home/gerard/wine
cvs -d $CVSROOT update -D "1999-06-01"
</screen>
</para>
<para>
The date format is <literal>YYYY-MM-DD</literal>.
</para>
<para>
Many messages will inform you that more recent files have
been deleted to set back the client cvs tree to the date
you asked, for example:
<screen>
cvs update: tsx11/ts_xf86dga2.c is no longer in the repository
</screen>
</para>
<para>
<command>cvs update</command> is not limited to upgrade to
a <emphasis>newer</emphasis> version as I have believed for far too long :-(
</para>
</listitem>
<listitem>
<para>
Now proceed as for a normal update:
</para>
<screen>
./configure
make depend && make
</screen>
<para>
When you have found the exact date when a bug was added to
the cvs tree, use something like :
<screen>
cvs -d $CVSROOT diff -D "1999-07-10" -D "1999-07-12"
</screen>
to get all the differences between the last cvs tree
version known to work and code that first displayed the
misbehavior.
</para>
<note>
<para>
I did not include flags for <command>diff</command>
since they are in my <filename>.cvsrc</filename> file:
</para>
<screen>
cvs -z 3
update -dPA
diff -u
</screen>
</note>
<para>
From this diff file, particularly the file names, and the
<filename>ChangeLog</filename>, it's usually possible to
find the different individual patches that were done at
this time.
</para>
<para>
If any non-programmer reads this, the fastest method to get
at the point where the problem occured is to use a binary
search, that is, if the problem occured in 1999, start at
mid-year, then is the problem is already here, back to 1st
April, if not, to 1st October, and so on.
</para>
</listitem>
<listitem>
<para>
The next step is to start from the last working version
and to dig the individual contributions from
<ulink url="http://www.integrita.com/cgi-local/lwgate.pl/WINE-PATCHES/">
http://www.integrita.com/cgi-local/lwgate.pl/WINE-PATCHES/</ulink>
(where the Wine patches mailing list is archived)
</para>
<para>
If the patch was done by the Wine maintainer or if it was
sent directly to his mail address without going first through
<ulink url="mailto:wine-patches@winehq.com">wine-patches</ulink>,
you are out of luck as you will never find the patch in
the archive. If it is, it's often possible to apply the
patches one by one to last working cvs snapshot, compile and test.
If you have saved the next candidate as
<filename>/home/gerard/buggedpatch1.txt</filename>:
</para>
<screen>
cd /home/gerard/wine
patch -p 0 &lt; /home/gerard/buggedpatch1.txt
</screen>
<para>
Beware that the committed patch is not always identical to
the patch that the author sent to wine-patches, as
sometimes the Wine maintainer changes things a bit.
</para>
<para>
If you find one patch that is getting the cvs source tree to
reproduce the problem, you have almost won; post the problem on
<systemitem>comp.emulators.windows.wine</systemitem> and there
is a chance that the author will jump in to suggest a fix; or
there is always the possibility to look hard at the patch until
it is coerced to reveal where is the bug :-)
</para>
</listitem>
</orderedlist>
</chapter>
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