Re: [PATCH v4 10/12] qtest/qmp-cmd-test: Make test build-independent from accelerator

[Philippe Mathieu-Daudé]

On 4/29/21 7:43 AM, Markus Armbruster wrote:
> Philippe Mathieu-Daudé <philmd@redhat.com> writes:
> 
>> Now than we can probe if the TCG accelerator is available
>> at runtime with a QMP command, do it once at the beginning
>> and only register the tests we can run.
>> We can then replace the #ifdef'ry by a runtime check.
>>
>> Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> 
> Please read the last remark first.  The other ones are detail; feel free
> to skip them until we're done with the last one.
> 
>> ---
>>  tests/qtest/qmp-cmd-test.c | 18 ++++++++++++++----
>>  1 file changed, 14 insertions(+), 4 deletions(-)

>> +    tcg_accel_available = qtest_has_accel("tcg");
>> +
> 
> When does tcg_accel_available differ from defined(CONFIG_TCG)?

qtest_has_accel("tcg") is a runtime check, while defined(CONFIG_TCG)
is build-time.

Having tests doing runtime checking allow to:

- have easier reviews, having less #ifdef'ry
- build them once for all targets
- build them once for all ./configure options
  (thinking about CI, the a single job could build the tests, then
  we run them using the QEMU binaries from other jobs)
- use the same binaries to test the built binary and the distribution
  installed one
- remove the dependencies between tests and binaries

> 
>>      g_test_init(&argc, &argv, NULL);
>>  
>>      qmp_schema_init(&schema);
>