[libvirt] VIR_TEST_REGENERATE_OUTPUT is broken (Was: [PATCH] qemuxml2argvtest: Adapt to ethernet automatic tap creation)

[Laine Stump]

On 03/23/2016 11:35 AM, Michal Privoznik wrote:
> After 9c17d665fdc5 the tap device for ethernet network type is
> automatically precreated before spawning qemu. Problem is, the
> qemuxml2argvtest wasn't updated and thus is failing. Because of
> all the APIs that new code is calling, I had to mock a lot. Also,
> since the tap FDs are labeled separately from the rest of the
> devices/files I had to enable NOP security driver for the test
> too.
>
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---

> --- a/tests/qemuxml2argvmock.c
> +++ b/tests/qemuxml2argvmock.c

> +}
> +
> +int
> +virCommandRun(virCommandPtr cmd ATTRIBUTE_UNUSED,
> +              int *exitstatus)
> +{
> +    if (exitstatus)
> +        *exitstatus = 0;
> +
> +    return 0;
> +}


The problem with mocking virCommandRun is that it is called by the test 
infrastructure (virTestRewrapFile(), which is used when regenerating the 
test results (VIR_TEST_REGENERATE_OUTPUT=1)).

After this commit that function silently fails, which results in 
virFileWriteStr() calling strlen(NULL) and a crash of the test. (Nobody 
noticed this before because it's only called if you set 
VIR_TEST_REGENERATE_OUTPUT *and* the results of one of the qemuxml2argv 
tests has changed).

So what's the most reasonable way to deal with this? I suppose we could 
rename virCommandRun to e.g. virCommandRunInternal() which would be 
called by a new virCommandRun(), then have virTestRewrapFile() call 
virCommandRunInternal() so that it wouldn't get the mocked version. That 
seems ugly, inefficient, and hackish, but I can't think of any way that 
isn't ugly, inefficient, and hackish...