[libvirt] [PATCH v2 2/4] virnetdev: Introduce virNetDevGetLinkInfo

[Michal Privoznik]

On 11.06.2014 11:19, Michal Privoznik wrote:
>>  <snip/>
>> Seems we should be able to set up a dummy /sys/class/net environment in
>> order to test the new API's... Something I attempted with my recently
>> posted scsi_host changes.
>
> Yeah, unit testing is certainly in place. But honestly, I thought it
> would blow the size of this patches up. Again, something that a follow
> up patch will do.
>

So, now that I'm thinking about how to implement this I see two possible 
ways which I'm unable to choose between:

1) mock higher level functions like virNetDevSysfsFile() or 
virNetDevSetupControl(). So if a function wants to reach say 
"/sys/class/net/eth0/operstate" we can direct it into 
"tests/virnetdevdata/class/net/eth0/operstate"
Pros:
- small set of high level functions, so the code should be rather small.
- we can keep whole sysfs dir struct in git

Cons:
- Unable to simulate some corner cases (e.g. EINVAL on read()).
- keeping whole sysfs dir struct in git

2) mock lowlevel functions, like open(), ioctl(), etc. There's plenty of 
functions in virnetdev.c that use lowlevel functions like socket(), 
ioctl() to get data.

Pros:
- we can model kernel behavior more closely (e.g. even run time setting 
of some values like MAC/IP addressese, link state, you name it)
- clean git

Cons:
- much more code

I'm not hesitant to write the code, but I'd rather have an agreement on 
the design before that.

Michal