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From Pedro Larroy <>
Subject Re: Improving and rationalizing unit tests
Date Mon, 16 Oct 2017 16:09:06 GMT
I think using a properly seeded and initialized (pseudo)random is actually
beneficial (and deterministic), handpicked examples are usually too
simplistic and miss corner cases.

Better yet is to use property based testing, which will pick corner cases
and do fuzzing automatically to check with high degree of confidence that a
testing condition holds.

Probably it would be good if we use a property based testing library in
adition to nose to check invariants.

A quick googling yields this one for python for example: does anyone
have experience or can recommend a nice property based testing library for


On Mon, Oct 16, 2017 at 4:56 PM, Bhavin Thaker <>

> I agree with Pedro.
> Based on various observations on unit test failures, I would like to
> propose a few guidelines to follow for the unit tests. Even though I use
> the word, “must” for my humble opinions below, please feel free to suggest
> alternatives or modifications to these guidelines:
> 1) 1a) Each unit test must have a run time budget <= X minutes. Say, X = 2
> minutes max.
> 1b) The total run time budget for all unit tests <= Y minutes. Say, Y = 60
> minutes max.
> 2) All Unit tests must have deterministic (not Stochastic) behavior. That
> is, instead of using the random() function to test a range of input values,
> each input test value must be carefully hand-picked to represent the
> commonly used input scenarios. The correct place to stochastically test
> random input values is to have continuously running nightly tests and NOT
> the sanity/smoke/unit tests for each PR.
> 3) All Unit tests must be as much self-contained and independent of
> external components as possible. For example, datasets required for the
> unit test must NOT be present on external website which, if unreachable,
> can cause test run failures. Instead, all datasets must be available
> locally.
> 4) It is impossible to test everything in unit tests and so only common
> use-cases and code-paths must be tested in unit-tests. Less common
> scenarios like integration with 3rd party products must be tested in
> nightly/weekly tests.
> 5) A unit test must NOT be disabled on a failure unless proven to exhibit
> unreliable behavior. The burden-of-proof for a test failure must be on the
> PR submitter and the PR must NOT be merged without a opening a new github
> issue explaining the problem. If the unit test is disabled for some reason,
> then the unit test must NOT be removed from the unit tests list; instead
> the unit test must be modified to add the following lines at the start of
> the test:
>     Print(“Unit Test DISABLED; see GitHub issue: NNNN”)
>     Exit(0)
> Please suggest modifications to the above proposal such that we can make
> the unit tests framework to be the rock-solid foundation for the active
> development of Apache MXNet (Incubating).
> Regards,
> Bhavin Thaker.
> On Mon, Oct 16, 2017 at 5:56 AM Pedro Larroy <
> >
> wrote:
> > Hi
> >
> > Some of the unit tests are extremely costly in terms of memory and
> compute.
> >
> > As an example in the gluon tests we are loading all the datasets.
> >
> > test_gluon_data.test_datasets
> >
> > Also running huge networks like resnets in test_gluon_model_zoo.
> >
> > This is ridiculously slow, and straight impossible on some embedded /
> > memory constrained devices, and anyway is making tests run for longer
> than
> > needed.
> >
> > Unit tests should be small, self contained, if possible pure (avoiding
> this
> > kind of dataset IO if possible).
> >
> > I think it would be better to split them in real unit tests and extended
> > integration test suites that do more intensive computation. This would
> also
> > help with the feedback time with PRs and CI infrastructure.
> >
> >
> > Thoughts?
> >

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