[U-Boot] [PATCH 1/1] test/py: catch errors occurring when reading the console

[Stephen Warren]

On 09/18/2018 06:43 PM, Heinrich Schuchardt wrote:
> On 09/18/2018 07:23 PM, Stephen Warren wrote:
>> On 09/18/2018 11:21 AM, Heinrich Schuchardt wrote:
>>> Spawn.exept has a try block without 'except'.
>>>
>>> If no output is available an OSError may arise. Catch this exception and
>>> continue testing.
>>>
>>> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
>>> Reviewed-by: Simon Glass <sjg at chromium.org>
>>> ---
>>> I suggest that Alex takes the patch because we need it when working on
>>> the
>>> efi-next branch.
>>>
>>> v2
>>>      replace TAB by spaces
>>>      fix typo in subject
>>
>> I'll point out that I still object to this.
> 
> On 09/18/2018 07:06 PM, Stephen Warren wrote:
>> This doesn't make sense at all. It catches all errors and ignores them.
>> It'll turn any error condition into a timeout (presumably, the expected
>> data being waited for will never appear) rather than dealing with it
>> immediately (due to the thrown exception). Why is this needed?
> 
> When the py test is running it is connected via pipes to the U-Boot
> process. If the U-Boot process ends due to a segmentation fault the
> pipes are broken. Trying to read from a broken pipe results in an OSError.
> 
> Before this patch this leads to an uncaught error in the Python script.
> The output that has occured up to this point is lost and not displayed.
> All further tests for the configuration are not run.

Ah. I think that's because Python is throwing an error rather than an 
exception. I would have assumed that py.test caught errors as well as 
exceptions, but perhaps not. I think what we should do here is catch 
errors and translate them into a new thrown exception. That way, 
everything outside the function would treat this as just another type of 
exception, and hence still capture/flush the output, mark the test 
immediately failed rather than having to wait for a timeout, etc.