Not Condition In xpath

I have the following xml :

<test1>
    <test2>
       <text>This is a question on xpath
       </text>
    </test2>
    <test3>
        <test2>
            <text>Do not extract this
             </text>
        </test2>
    </test3>
</test1> 

I need to extract text within test2/text but not if test2 comes inside test3. How can this be done in xpath ? I tried with findall with something like:

for p in lxml_tree.xpath('.//test2',namespaces={'w':w}):
    for q in p.iterancestors():
        if q.tag=="test3":
           break
        else:
            text+= ''.join(t.text for t in p.xpath('.//text'))

but this doesn't work . I guess xpath has a better way in a single expression to exclude it. Expected output: text = "This is a question on xpath"