On 26.09.19 16:07, Vladimir Sementsov-Ogievskiy wrote: > 20.09.2019 18:27, Max Reitz wrote: >> Signed-off-by: Max Reitz <mre...@redhat.com> >> --- >> tests/qemu-iotests/iotests.py | 48 +++++++++++++++++++++++++++++++++++ >> 1 file changed, 48 insertions(+) >> >> diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py >> index daed4ee013..e6fb46287d 100644 >> --- a/tests/qemu-iotests/iotests.py >> +++ b/tests/qemu-iotests/iotests.py >> @@ -670,6 +670,54 @@ class VM(qtest.QEMUQtestMachine): >> >> return fields.items() <= ret.items() >> >> + ''' >> + @path is a string whose components are separated by slashes. >> + The first component is a node name, the rest are child names. >> + Examples: >> + - "qcow2-node/backing/file" >> + - "quorum-node/children.2/file" > > Possibly, separting node-name to first parameter and keeping child-path as > a second will simplify code a bit, and be more useful for cases when on caller > part node-name is in variable.
Sounds good.
>> +
>> + @expected_node may be None.
>> +
>> + @graph may be None or the result of an x-debug-query-block-graph
>> + call that has already been performed.
>> + '''
>> + def assert_block_path(self, path, expected_node, graph=None):
>> + if graph is None:
>> + graph = self.qmp('x-debug-query-block-graph')['return']
>
> Yay! I'm happy to see that it's useful.
:-)
It’s probably the best query function we have.
>> +
>> + iter_path = iter(path.split('/'))
>> + root = next(iter_path)
>> + try:
>> + node = next(node for node in graph['nodes'] if node['name'] ==
>> root)
>> + except StopIteration:
>> + node = None
>
> for such usage next has second optional argument: next(iterator[, default])
Great!
> (don't think I teach you Python, actually you teach me, as before I didn't
> know
> correct way to search first element with condition)
We learn from one another, which is the best case.
>> +
>> + for path_node in iter_path:
>> + assert node is not None, 'Cannot follow path %s' % path
>> +
>> + try:
>> + node_id = next(edge['child'] for edge in graph['edges'] \
>> + if edge['parent'] ==
>> node['id'] and
>> + edge['name'] == path_node)
>
> Hmm here you allow default StopIteration exception [1]
>
>
>> +
>> + node = next(node for node in graph['nodes'] \
>> + if node['id'] == node_id)
>> + except StopIteration:
>> + node = None
>
> actually, I think this will never happen, so we may simplify code and allow
> it to
> throw StopIteration exception in this impossible case..
This is for a use case where the next child simply doesn’t exist, so you
can do:
assert_block_path('qcow2-node/backing', None)
To verify that the qcow2 node has no backing file.
>> +
>> + assert node is not None or expected_node is None, \
>> + 'No node found under %s (but expected %s)' % \
>> + (path, expected_node)
>
> node may be None here only from last iteration, but it can't happen: if we
> have edge
> with child, we'll for sure have node with such node-name in graph
node will always be set by the try-except block, won’t it?
>> +
>> + assert expected_node is not None or node is None, \
>> + 'Found node %s under %s (but expected none)' % \
>> + (node['name'], path)
>
> hmm, so expected_node=None means we want to prove that there is no such node?
> It should
> be mentioned in comment above the function. But this don't work due to [1]
Hm, I seem to remember I tested all cases locally and they all worked.
Max
>> +
>> + if node is not None and expected_node is not None:
>> + assert node['name'] == expected_node, \
>> + 'Found node %s under %s (but expected %s)' % \
>> + (node['name'], path, expected_node)
>>
>> index_re = re.compile(r'([^\[]+)\[([^\]]+)\]')
>>
>>
>
>
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