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Adding notes
============
When a test fails, Hypothesis will normally print output that looks like this:
.. code::
Falsifying example: test_a_thing(x=1, y="foo")
Sometimes you want to add some additional information to a failure, such as the output of some intermediate step in your test. The |note| function lets you do this:
.. code-block:: pycon
>>> from hypothesis import given, note, strategies as st
>>> @given(st.lists(st.integers()), st.randoms())
... def test_shuffle_is_noop(ls, r):
... ls2 = list(ls)
... r.shuffle(ls2)
... note(f"Shuffle: {ls2!r}")
... assert ls == ls2
...
>>> try:
... test_shuffle_is_noop()
... except AssertionError:
... print("ls != ls2")
...
Falsifying example: test_shuffle_is_noop(ls=[0, 1], r=RandomWithSeed(1))
Shuffle: [1, 0]
ls != ls2
|note| is like a print statement that gets attached to the falsifying example reported by Hypothesis. It's also reported by :ref:`observability <observability>`, and shown for all examples (if |settings.verbosity| is set to |Verbosity.verbose| or higher).
.. note::
|event| is a similar function which tells Hypothesis to count the number of test cases which reported each distinct value you pass, for inclusion in :ref:`test statistics <statistics>` and :ref:`observability reports <observability>`.
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