Sweden-Number/documentation/testing.sgml

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<chapter id="testing">
<title>Writing Conformance tests</title>
<para>
Note: This part of the documentation is still very much a work in
progress and is in no way complete.
</para>
<sect1 id="testing-intro">
<title>Introduction</title>
<para>
With more The Windows API follows no standard, it is itself a defacto
standard, and deviations from that standard, even small ones, often
cause applications to crash or misbehave in some way. Furthermore
a conformance test suite is the most accurate (if not necessarily
the most complete) form of API documentation and can be used to
supplement the Windows API documentation.
</para>
<para>
Writing a conformance test suite for more than 10000 APIs is no small
undertaking. Fortunately it can prove very useful to the development
of Wine way before it is complete.
<itemizedlist>
<listitem>
<para>
The conformance test suite must run on Windows. This is
necessary to provide a reasonable way to verify its accuracy.
Furthermore the tests must pass successfully on all Windows
platforms (tests not relevant to a given platform should be
skipped).
</para>
<para>
A consequence of this is that the test suite will provide a
great way to detect variations in the API between different
Windows versions. For instance, this can provide insights
into the differences between the, often undocumented, Win9x and
NT Windows families.
</para>
<para>
However, one must remember that the goal of Wine is to run
Windows applications on Linux, not to be a clone of any specific
Windows version. So such variations must only be tested for when
relevant to that goal.
</para>
</listitem>
<listitem>
<para>
Writing conformance tests is also an easy way to discover
bugs in Wine. Of course, before fixing the bugs discovered in
this way, one must first make sure that the new tests do pass
successfully on at least one Windows 9x and one Windows NT
version.
</para>
<para>
Bugs discovered this way should also be easier to fix. Unlike
some mysterious application crashes, when a conformance test
fails, the expected behavior and APIs tested for are known thus
greatly simplifying the diagnosis.
</para>
</listitem>
<listitem>
<para>
To detect regressions. Simply running the test suite regularly
in Wine turns it into a great tool to detect regressions.
When a test fails, one immediately knows what was the expected
behavior and which APIs are involved. Thus regressions caught
this way should be detected earlier, because it is easy to run
all tests on a regular basis, and easier to fix because of the
reduced diagnosis work.
</para>
</listitem>
<listitem>
<para>
Tests written in advance of the Wine development (possibly even
by non Wine developpers) can also simplify the work of the
futur implementer by making it easier for him to check the
correctness of his code.
</para>
</listitem>
<listitem>
<para>
FIXME: Ports to new architectures involve New ports involve modifying core parts of Wine:
synchronization, exception handling, thread management, etc.
After such modifications extensive testing is necessary to
make sure the changes did not To check the correctness of new ports.
</para>
</listitem>
</itemizedlist>
</para>
</sect1>
<sect1 id="testing-what">
<title>What to test for?</title>
<para>
The first thing to test for is the documented behavior of APIs
and such as CreateFile. For instance one can create a file using a
long pathname, check that the behavior is correct when the file
already exists, try to open the file using the corresponding short
pathname, convert the filename to Unicode and try to open it using
CreateFileW, and all other things which are documented and that
applications rely on.
</para>
<para>
While the testing framework is not specifically geared towards this
type of tests, it is also possible to test the behavior of Windows
messages. To do so, create a window, preferably a hidden one so that
it does not steal the focus when running the tests, and send messages
to that window or to controls in that window. Then, in the message
procedure, check that you receive the expected messages and with the
correct parameters.
</para>
<para>
For instance you could create an edit control and use WM_SETTEXT to
set its contents, possibly check length restrictions, and verify the
results using WM_GETTEXT. Similarly one could create a listbox and
check the effect of LB_DELETESTRING on the list's number of items,
selected items list, highlighted item, etc.
</para>
<para>
However, undocumented behavior should not be tested for unless there
is an application that relies on this behavior, and in that case the
test should mention that application, or unless one can strongly
expect applications to rely on this behavior, typically APIs that
return the required buffer size when the buffer pointer is NULL.
</para>
</sect1>
<sect1 id="testing-perl-vs-c">
<title>Why have both Perl and C tests?</title>
<para>
</para>
</sect1>
<sect1 id="testing-running">
<title>Running the tests on Windows</title>
<para>
The simplest way to run the tests in Wine is to type 'make test' in
the Wine sources top level directory. This will run all the Wine
conformance tests.
</para>
<para>
The tests for a specific Wine library are located in a 'tests'
directory in that library's directory. Each test is contained in a
file, either a '.pl' file (e.g. <filename>dlls/kernel/tests/atom.pl</>)
for a test written in perl, or a '.c' file (e.g.
<filename>dlls/kernel/tests/thread.c</>) for a test written in C. Each
file itself contains many checks concerning one or more related APIs.
</para>
<para>
So to run all the tests related to a given Wine library, go to the
corresponding 'tests' directory and type 'make test'. This will
compile the C tests, run the tests, and create an
'<replaceable>xxx</>.ok' file for each test that passes successfully.
And if you only want to run the tests contained in the
<filename>thread.c</> file of the kernel library, you would do:
<screen>
<prompt>$ </>cd dlls/kernel/tests
<prompt>$ </>make thread.ok
</screen>
</para>
<para>
Note that if the test has already been run and is up to date (i.e. if
neither the kernel library nor the <filename>thread.c</> file has
changed since the <filename>thread.ok</> file was created), then make
will say so. To force the test to be re-run, delete the
<filename>thread.ok</> file, and run the make command again.
</para>
<para>
You can also run tests manually using a command similar to the
following:
<screen>
<prompt>$ </>runtest -q -M kernel32.dll -p kernel32_test.exe.so thread.c
<prompt>$ </>runtest -p kernel32_test.exe.so thread.c
thread.c: 86 tests executed, 5 marked as todo, 0 failures.
</screen>
The '-P wine' options defines the platform that is currently being
tested; the '-q' option causes the testing framework not to report
statistics about the number of successfull and failed tests. Run
<command>runtest -h</> for more details.
</para>
</sect1>
<sect1 id="testing-c-test">
<title>Inside a C test</title>
<para>
When writing new checks you can either modify an existing test file or
add a new one. If your tests are related to the tests performed by an
existing file, then add them to that file. Otherwise create a new .c
file in the tests directory and add that file to the
<varname>CTESTS</> variable in <filename>Makefile.in</>.
</para>
<para>
A new test file will look something like the following:
<screen>
#include &lt;wine/test.h&gt;
#include &lt;winbase.h&gt;
/* Maybe auxiliary functions and definitions here */
START_TEST(paths)
{
/* Write your checks there or put them in functions you will call from
* there
*/
}
</screen>
</para>
<para>
The test's entry point is the START_TEST section. This is where
execution will start. You can put all your tests in that section but
it may be better to split related checks in functions you will call
from the START_TEST section. The parameter to START_TEST must match
the name of the C file. So in the above example the C file would be
called <filename>paths.c</>.
</para>
<para>
Tests should start by including the <filename>wine/test.h</> header.
This header will provide you access to all the testing framework
functions. You can then include the windows header you need, but make
sure to not include any Unix or Wine specific header: tests must
compile on Windows.
</para>
<!-- FIXME: Can we include windows.h now? We should be able to but currently __WINE__ is defined thus making it impossible. -->
<!-- FIXME: Add recommendations about what to print in case of a failure: be informative -->
<para>
You can use <function>trace</> to print informational messages. Note
that these messages will only be printed if 'runtest -v' is being used.
<screen>
trace("testing GlobalAddAtomA");
trace("foo=%d",foo);
</screen>
<!-- FIXME: Make sure trace supports %d... -->
</para>
<para>
Then just call functions and use <function>ok</> to make sure that
they behaved as expected:
<screen>
ATOM atom = GlobalAddAtomA( "foobar" );
ok( GlobalFindAtomA( "foobar" ) == atom, "could not find atom foobar" );
ok( GlobalFindAtomA( "FOOBAR" ) == atom, "could not find atom FOOBAR" );
</screen>
The first parameter of <function>ok</> is an expression which must
evaluate to true if the test was successful. The next parameter is a
printf-compatible format string which is displayed in case the test
failed, and the following optional parameters depend on the format
string.
</para>
<para>
It is important to display an informative message when a test fails:
a good error message will help the Wine developper identify exactly
what went wrong without having to add too many other printfs. For
instance it may be useful to print the error code if relevant, or the
expected value and effective value. In that respect, for some tests
you may want to define a macro such as the following:
<screen>
#define eq(received, expected, label, type) \
ok((received) == (expected), "%s: got " type " instead of " type, (label),(received),(expected))
...
eq( b, curr_val, "SPI_{GET,SET}BEEP", "%d" );
</screen>
</para>
<para>
Note
</para>
</sect1>
<sect1 id="testing-platforms">
<title>Handling platform issues</title>
<para>
Some checks may be written before they pass successfully in Wine.
Without some mechanism, such checks would potentially generate
hundred of known failures for months each time the tests are being run.
This would make it hard to detect new failures caused by a regression.
or to detect that a patch fixed a long standing issue.
</para>
<para>
Thus the Wine testing framework has the concept of platforms and
groups of checks can be declared as expected to fail on some of them.
In the most common case, one would declare a group of tests as
expected to fail in Wine. To do so, use the following construct:
<screen>
todo_wine {
SetLastError( 0xdeadbeef );
ok( GlobalAddAtomA(0) == 0 && GetLastError() == 0xdeadbeef, "failed to add atom 0" );
}
</screen>
On Windows the above check would be performed normally, but on Wine it
would be expected to fail, and not cause the failure of the whole
test. However. If that check were to succeed in Wine, it would
cause the test to fail, thus making it easy to detect when something
has changed that fixes a bug. Also note that todo checks are accounted
separately from regular checks so that the testing statistics remain
meaningful. Finally, note that todo sections can be nested so that if
a test only fails on the cygwin and reactos platforms, one would
write:
<screen>
todo("cygwin") {
todo("reactos") {
...
}
}
</screen>
<!-- FIXME: Would we really have platforms such as reactos, cygwin, freebsd & co? -->
But specific platforms should not be nested inside a todo_wine section
since that would be redundant.
</para>
<para>
When writing tests you will also encounter differences between Windows
9x and Windows NT platforms. Such differences should be treated
differently from the platform issues mentioned above. In particular
you should remember that the goal of Wine is not to be a clone of any
specific Windows version but to run Windows applications on Unix.
</para>
<para>
So, if an API returns a different error code on Windows 9x and
Windows NT, your check should just verify that Wine returns one or
the other:
<screen>
ok ( GetLastError() == WIN9X_ERROR || GetLastError() == NT_ERROR, ...);
</screen>
</para>
<para>
If an API is only present on some Windows platforms, then use
LoadLibrary and GetProcAddress to check if it is implemented and
invoke it. Remember, tests must run on all Windows platforms.
Similarly, conformance tests should nor try to correlate the Windows
version returned by GetVersion with whether given APIs are
implemented or not. Again, the goal of Wine is to run Windows
applications (which do not do such checks), and not be a clone of a
specific Windows version.
</para>
<para>
FIXME: What about checks that cause the process to crash due to a bug?
</para>
</sect1>
<!-- FIXME: Strategies for testing threads, testing network stuff,
file handling, eq macro... -->
</chapter>
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