Shrinking a given example

[Nicholas Chammas]

A user reported a bug in a function and provided a reproduction. I decided to write a test for this function to see if Hypothesis could find the same bug.

The test looks like this:

@given(data=lists(tuples(floats())))
def test_percentile(data):
    ...

I’ve run this test with up to 100,000 examples, but Hypothesis is not finding this bug. A very specific set of circumstances that I do not understand need to line up precisely for this bug to reveal itself.

I am now trying to figure out something different: Given a known failing example, can Hypothesis help me shrink it to its simplest form?

The reproduction provided by the user is a list that’s 373 elements long. I managed to manually shrink it down to 45 elements.

Is there any way to get Hypothesis to shrink the known failing example even further?

[Zac Hatfield Dodds]

Great question!  This comes up often enough that I've cross-posted and answered it at https://stackoverflow.com/a/77818444/9297601 - unfortunately the short version is "no, Hypothesis can only shrink examples it generated", but using `hypothesis.target()` might make it easier to (re)generate a known failing example.

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