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https://issues.apache.org/jira/browse/CASSANDRA-14298?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16476666#comment-16476666
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Patrick Bannister commented on CASSANDRA-14298:
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I've made a lot of progress porting cqlshlib to Python 3. Along the way I've
been taking notes on all the areas that I think would require extra effort for
cross compatibility with Python 2.
I don't have a complete plan yet, but I have some observations.
In terms of level of effort and complexity, this is not going to be as simple
as running 2to3 and then adding a few imports from future and six. However, we
won't need to rearchitect the library either. So far I've found that existing
classes and functions work with just a few tweaks to their implementation,
mostly around IO and strings vs. bytes.
The biggest challenge, regardless of whether we go straight Python 3 or
cross-compatible, is going to be adequately testing the result. The cqlshlib
unittests and the cqlsh_tests have been useful to help find bugs, but I'm not
confident that our tests have enough code coverage to exercise everything. We
would need a strategy for more comprehensive testing.
Some specifics:
* The SaferScanner class in saferscanner.py requires a slightly different
implementation in Python 2 vs. Python 3, because of changes in the internals of
the re module for regular expressions.
* copyutil.py, formatting.py, and displaying.py have needed the most work so
far, since they have a lot of IO and serialization.
* The formatter for blobs in formatting.py needs a different implementation in
Python 2 vs. Python 3, because of changes in the behavior of binascii.hexlify.
* On the dtests side, there are several tests that fail intermittently due to
different sorting between expected results and observed results. The result of
these tests is flaky depending on what randomly occurring sort happens to come
out of the test. I've been able to get these tests to pass consistently by
sorting results just before asserting equality.
* Another notable dtest issue: in the cqlsh_copy_tests, the bulk_round_trip
tests that use the blogposts profile are failing because of a limitation of the
Python csv.reader, which is used in cqlshlib3 and in the bulk_round_trip tests.
Python's csv.reader chokes on newlines and null characters, but the
cassandra-stress tool's Strings Generator subclass generates both of these
things in text fields.
> cqlshlib tests broken on b.a.o
> ------------------------------
>
> Key: CASSANDRA-14298
> URL: https://issues.apache.org/jira/browse/CASSANDRA-14298
> Project: Cassandra
> Issue Type: Bug
> Components: Build, Testing
> Reporter: Stefan Podkowinski
> Assignee: Patrick Bannister
> Priority: Major
> Labels: cqlsh, dtest
> Attachments: CASSANDRA-14298-old.txt, CASSANDRA-14298.txt,
> cqlsh_tests_notes.md
>
>
> It appears that cqlsh-tests on builds.apache.org on all branches stopped
> working since we removed nosetests from the system environment. See e.g.
> [here|https://builds.apache.org/view/A-D/view/Cassandra/job/Cassandra-trunk-cqlsh-tests/458/cython=no,jdk=JDK%201.8%20(latest),label=cassandra/console].
> Looks like we either have to make nosetests available again or migrate to
> pytest as we did with dtests. Giving pytest a quick try resulted in many
> errors locally, but I haven't inspected them in detail yet.
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