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<chapter id="testing">
<title>Writing Conformance tests</title>
<sect1 id="testing-intro">
<title>Introduction</title>
<para>
The Windows API follows no standard, it is itself a de facto standard,
and deviations from that standard, even small ones, often cause
applications to crash or misbehave in some way.
</para>
<para>
The question becomes, "How do we ensure compliance with that standard?"
The answer is, "By using the API documentation available to us and
backing that up with conformance tests." 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 developers) can also simplify the work of the
future implementer by making it easier for him to check the
correctness of his code.
</para>
</listitem>
<listitem>
<para>
Conformance tests will also come in handy when testing Wine on
new (or not as widely used) architectures such as FreeBSD,
Solaris x86 or even non-x86 systems. Even when the port does
not involve any significant change in the thread management,
exception handling or other low-level aspects of Wine, new
architectures can expose subtle bugs that can be hard to
diagnose when debugging regular (complex) applications.
</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-wine">
<title>Running the tests in Wine</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 (e.g. <filename>dlls/kernel/tests/thread.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 tests, run them, 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>$ </>../../../tools/runtest -q -M kernel32.dll -p kernel32_test.exe.so thread.c
<prompt>$ </>../../../tools/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. Remove the '-q' option if you want the testing framework
to report statistics about the number of successful and failed tests.
Run <command>runtest -h</> for more details.
</para>
</sect1>
<sect1 id="cross-compiling-tests">
<title>Cross-compiling the tests with MinGW</title>
<sect2>
<title>Setup of the MinGW cross-compiling environment</title>
<para>
Here are some instructions to setup MinGW on different Linux
distributions and *BSD.
</para>
<sect3>
<title>Debian GNU/Linux</title>
<para>
On Debian all you need to do is type <command>apt-get install
mingw32</>.
</para>
</sect3>
<sect3>
<title>Red Hat Linux like rpm systems</title>
<para>
This includes Fedora Core, Red Hat Enterprise Linux, Mandrake,
most probably SuSE Linux too, etc. But this list isn't exhaustive;
the following steps should probably work on any rpm based system.
</para>
<para>
Download and install the latest rpm's from
<ulink url="http://mirzam.it.vu.nl/mingw/">MinGW RPM packages</>.
Alternatively you can follow the instructions on that page and
build your own packages from the source rpm's listed there as well.
</para>
</sect3>
<sect3>
<title>*BSD</title>
<para>
The *BSD systems have in their ports collection a port for the
MinGW cross-compiling environment. Please see the documentation
of your system about how to build and install a port.
</para>
</sect3>
</sect2>
<sect2>
<title>Compiling the tests</title>
<para>
Having the cross-compiling environment set up the generation of the
Windows executables is easy by using the Wine build system.
</para>
<para>
If you had already run <command>configure</>, then delete
<filename>config.cache</> and re-run <command>configure</>.
You can then run <command>make crosstest</>. To sum up:
<screen>
<prompt>$ </><userinput>rm config.cache</>
<prompt>$ </><userinput>./configure</>
<prompt>$ </><userinput>make crosstest</>
</screen>
</para>
</sect2>
</sect1>
<sect1 id="testing-windows">
<title>Building and running the tests on Windows</title>
<sect2>
<title>Using pre-compiled binaries</title>
<para>
Unfortunately there are no pre-compiled binaries yet. However if
send an email to the Wine development list you can probably get
someone to send them to you, and maybe motivate some kind soul to
put in place a mechanism for publishing such binaries on a regular
basis.
</para>
</sect2>
<sect2>
<title>With Visual C++</title>
<itemizedlist>
<listitem><para>
If you are using Visual Studio 6, make sure you have the
"processor pack" from
<ulink url="http://msdn.microsoft.com/vstudio/downloads/tools/ppack/default.aspx">http://msdn.microsoft.com/vstudio/downloads/tools/ppack/default.aspx</>.
The processor pack fixes <emphasis>"error C2520: conversion from
unsigned __int64 to double not implemented, use signed __int64"</>.
However note that the "processor pack" is incompatible with
Visual Studio 6.0 Standard Edition, and with the Visual Studio 6
Service Pack 6. If you are using Visual Studio 7 or greater you
do not need the processor pack. In either case it is recommended
to the most recent compatible Visual Studio
<ulink url="http://msdn.microsoft.com/vstudio/downloads/updates/sp/">service pack</>.
</para></listitem>
<listitem><para>
get the Wine sources
</para></listitem>
<listitem><para>
Run msvcmaker to generate Visual C++ project files for the tests.
'msvcmaker' is a perl script so you may be able to run it on
Windows.
<screen>
<prompt>$ </>./tools/winapi/msvcmaker --no-wine
</screen>
</para></listitem>
<listitem><para>
If the previous steps were done on your Linux development
machine, make the Wine sources accessible to the Windows machine
on which you are going to compile them. Typically you would do
this using Samba but copying them altogether would work too.
</para></listitem>
<listitem><para>
On the Windows machine, open the <filename>winetest.dsw</>
workspace. This will load each test's project. For each test there
are two configurations: one compiles the test with the Wine
headers, and the other uses the Microsoft headers.
</para></listitem>
<listitem><para>
If you choose the "Win32 MSVC Headers" configuration, most of the
tests will not compile with the regular Visual Studio headers. So
to use this configuration, download and install a recent
<ulink url="http://www.microsoft.com/msdownload/platformsdk/sdkupdate/">Platform SDK</>
(the download requires Internet Explorer!), as well as the latest
<ulink url="http://msdn.microsoft.com/library/default.asp?url=/downloads/list/directx.asp">DirectX SDK</>.
Then, <ulink url="http://msdn.microsoft.com/library/default.asp?url=/library/EN-US/sdkintro/sdkintro/installing_the_platform_sdk_with_visual_studio.asp">configure Visual Studio</>
to use these SDK's headers and libraries. Alternately you could go
to the <menuchoice><guimenu>Project</> <guimenu>Settings...</></>
menu and modify the settings appropriately, but you would then
have to redo this whenever you rerun msvcmaker.
</para></listitem>
<listitem><para>
Open the <menuchoice><guimenu>Build</> <guimenu>Batch
build...</></> menu and select the tests and build configurations
you want to build. Then click on <guibutton>Build</>.
</para></listitem>
<listitem><para>
To run a specific test from Visual C++, go to
<menuchoice><guimenu>Project</> <guimenu>Settings...</></>. There
select that test's project and build configuration and go to the
<guilabel>Debug</> tab. There type the name of the specific test
to run (e.g. 'thread') in the <guilabel>Program arguments</>
field. Validate your change by clicking on <guibutton>Ok</> and
start the test by clicking the red exclamation mark (or hitting
'F5' or any other usual method).
</para></listitem>
<listitem><para>
You can also run the tests from the command line. You will find
them in either <filename>Output\Win32_Wine_Headers</> or
<filename>Output\Win32_MSVC_Headers</> depending on the build
method. So to run the kernel 'path' tests you would do:
<screen>
<prompt>C:\&gt;</>cd dlls\kernel\tests\Output\Win32_MSVC_Headers
<prompt>C:\dlls\kernel\tests\Output\Win32_MSVC_Headers&gt;</>kernel32_test path
</screen>
</para></listitem>
</itemizedlist>
</sect2>
<sect2>
<title>With MinGW</title>
<para>
Wine's build system already has support for building tests with a MinGW
cross-compiler. See the section above called 'Setup of the MinGW
cross-compiling environment' for instructions on how to set things up.
When you have a MinGW environment installed all you need to do is rerun
configure and it should detect the MinGW compiler and tools. Then run
'make crosstest' to start building the tests.
</para>
</sect2>
</sect1>
<sect1 id="testing-test">
<title>Inside a 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>
<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>
</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>
</sect1>
<sect1 id="testing-error-messages">
<title>Writing good error messages</title>
<para>
The message that is printed when a test fails is
<emphasis>extremely</> important.
</para>
<para>
Someone will take your test, run it on a Windows platform that
you don't have access to, and discover that it fails. They will then
post an email with the output of the test, and in particular your
error message. Someone, maybe you, will then have to figure out from
this error message why the test failed.
</para>
<para>
If the error message contains all the relevant information that will
be easy. If not, then it will require modifying the test, finding
someone to compile it on Windows, sending the modified version to the
original tester and waiting for his reply. In other words, it will
be long and painful.
</para>
<para>
So how do you write a good error message? Let's start with an example
of a bad error message:
<screen>
ok(GetThreadPriorityBoost(curthread,&amp;disabled)!=0,
"GetThreadPriorityBoost Failed");
</screen>
This will yield:
<screen>
thread.c:123: Test failed: GetThreadPriorityBoost Failed
</screen>
</para>
<para>
Did you notice how the error message provides no information about
why the test failed? We already know from the line number exactly
which test failed. In fact the error message gives strictly no
information that cannot already be obtained by reading the code. In
other words it provides no more information than an empty string!
</para>
<para>
Let's look at how to rewrite it:
<screen>
BOOL rc;
...
rc=GetThreadPriorityBoost(curthread,&amp;disabled);
ok(rc!=0 && disabled==0,"rc=%d error=%ld disabled=%d",
rc,GetLastError(),disabled);
</screen>
This will yield:
<screen>
thread.c:123: Test failed: rc=0 error=120 disabled=0
</screen>
</para>
<para>
When receiving such a message, one would check the source, see that
it's a call to GetThreadPriorityBoost, that the test failed not
because the API returned the wrong value, but because it returned an
error code. Furthermore we see that GetLastError() returned 120 which
winerror.h defines as ERROR_CALL_NOT_IMPLEMENTED. So the source of
the problem is obvious: this Windows platform (here Windows 98) does
not support this API and thus the test must be modified to detect
such a condition and skip the test.
</para>
<para>
So a good error message should provide all the information which
cannot be obtained by reading the source, typically the function
return value, error codes, and any function output parameter. Even if
more information is needed to fully understand a problem,
systematically providing the above is easy and will help cut down the
number of iterations required to get to a resolution.
</para>
<para>
It may also be a good idea to dump items that may be hard to retrieve
from the source, like the expected value in a test if it is the
result of an earlier computation, or comes from a large array of test
values (e.g. index 112 of _pTestStrA in vartest.c). 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>
</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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