[CMake] Unit tests, but not CTest

[Michael Hertling]

On 05/13/2010 07:36 AM, Magnus Therning wrote:
> On 13/05/10 02:31, Michael Hertling wrote:
>> On 05/11/2010 10:51 AM, Magnus Therning wrote:
>>> I'm still having problems with this.
>>>
>>> I put together this:
>>>
>>>     project( test-post-build NONE )
>>>     cmake_minimum_required( VERSION 2.8 )
>>>
>>>     set( output ${CMAKE_CURRENT_BINARY_DIR}/foo )
>>>     add_custom_command( OUTPUT ${output}
>>>         COMMAND touch ${output}
>>>         COMMENT "Touching foo"
>>>         )
>>>     add_custom_target( foo.build ALL DEPENDS ${output} )
>>>
>>>     add_custom_command( TARGET ${output}
>>>         POST_BUILD
>>>         COMMAND echo "POST_BUILD ${output}"
>>>         )
>>>
>>>     add_custom_command( TARGET foo.build
>>>         POST_BUILD
>>>         COMMAND echo "POST_BUILD foo.build"
>>>         )
>>>
>>> Based on your description above I expected this behaviour:
>>>
>>>     % cmake ..
>>>     -- Configuring done
>>>     -- Generating done
>>>     -- Build files have been written to:
>>> /home/magnus/Play/test/cmake/post_build/_build
>>>     % make
>>>     Scanning dependencies of target foo.build
>>>     [  0%] Touching foo
>>>     POST_BUILD /home/magnus/Play/test/cmake/post_build/_build/foo
>>>     POST_BUILD foo.build
>>>     [100%] Built target foo.build
>>>     % make
>>>     POST_BUILD foo.build
>>>     [100%] Built target foo.build
>>>
>>> However, that's not the case.  I only ever see the 'POST_BUILD foo.build'
>>> printed. [...]
>>
>> AFAIK, this is because your "add_custom_command(TARGET ${output} ...)"
>> is not associated with an actual target but with just a file whereas
>> "add_custom_command(TARGET foo.build ...)" actually refers to a target
>> "foo.build" defined by ADD_CUSTOM_TARGET(). Indeed, you may issue any
>> ADD_CUSTOM_COMMAND(TARGET ...) for undefined targets without causing
>> an error, but their commands will never be executed, of course.
>>
>>> [...] So, what target can I use to get the desired behaviour of the
>>> POST_BUILD only being run after an actual build?
>>
>> Just use a target - but really a target - after whose rebuild you like
>> to have your post-build custom commands being run.
>>
>> Hope this helps.
> 
> I'm sorry, but it doesn't :-(  I have two POST_BUILD commands above, one
> attached to the creation of a file and one to a target.  The former I thought
> was attached to the creation of a file (the OUTPUT of a command) the latter to
> a custom target (which depends on the OUTPUT of the former).  The former is
> *never* run, the latter is *always* run.  The explanations in this thread so
> far has explained why CMake behaves this way, but how do I make the creation
> of the file into "a target - but really a target" so I can attach the
> POST_BUILD command to it?
> 
> Would you mind correcting my CMake script from above as an example of how it
> can be done?
> 
> I have the following:
> 
>      project( test-post-build NONE )
>      cmake_minimum_required( VERSION 2.8 )
> 
>      set( output ${CMAKE_CURRENT_BINARY_DIR}/foo )
>      add_custom_command( OUTPUT ${output}
>          COMMAND touch ${output}
>          COMMENT "Touching foo"
>          )
> 
> I now want the text "POST_BUILD" echoed to stdout iff the command to create
> ${output} is run.  (With the explanations I've gotten in this thread so far I
> don't even see how that can be done.)

OK, I see. Perhaps, the solution for your concern is pretty easy: Try

     add_custom_command( OUTPUT ${output}
         COMMAND touch ${output}
         COMMAND echo "POST_BUILD ${output}"
         COMMENT "Touching foo"
         )

and forget the "add_custom_command( TARGET ${output} ... )". This just
means that the latter's command is directly tied to the generation of
${output}, and so, you even get exactly what you expected at first:

% cmake ..
-- Configuring done
-- Generating done
-- Build files have been written to: [...]
% make
Scanning dependencies of target foo.build
[  0%] Touching foo
POST_BUILD [...]/foo
POST_BUILD foo.build
[100%] Built target foo.build
% make
POST_BUILD foo.build
[100%] Built target foo.build

In other words, there would be no need to attach additional commands to
ADD_CUSTOM_COMMAND(OUTPUT ...) via ADD_CUSTOM_COMMAND(TARGET ...), but
one can specify them directly within the former, and for more complex
operations, one can use ADD_CUSTOM_COMMAND()'s DEPENDS option to
trigger arbitrary targets when the OUTPUT is regenerated.

Is this the desired behaviour?

Regards,

Michael