[TIP] Identifying slowest py.test fixtures

[René Dudfield]

What about running pytest under the python profiler?

On Sat, Jul 23, 2016 at 4:42 PM, Bruno Oliveira <nicoddemus at gmail.com>
wrote:

>
>
> On Sat, Jul 23, 2016 at 11:29 AM André Caron <andre.l.caron at gmail.com>
> wrote:
>
>>
>> These two new hooks look like what was looking for, so guess that yes,
>> this will help a lot :-)  Do you have a ballpark-figure of how soon is
>> "soon"?
>>
>
> We are aiming for a release right after EuroPython, probably on the week
> of August 1st.
>
> Unfortunately, printing is subject to log capture plug-ins, so it's very
>> inconvenient.  I see your example plug-in uses printing as well.
>>
>
> Oh sorry, I meant to demonstrate only how to use the new hooks, certainly
> printing is not the way to go.
>
> How would I go about printing a report at the end like the `--durations`
>> argument does?  I assume I also need to use the `pytest_terminal_summary()`
>> hook, but I'm not sure how to pass info from your example
>> `pytest_fixture_setup()` to the reporting function.  Any hints?
>>
>
> You are right, `pytest_terminal_summary` is the best way to approach this.
> As to how to pass the information, aside from using global variables you
> could implement a plugin class yourself and register it during
> `pytest_configure`:
>
> class MeasureSetupsPlugin:
>
>     def __init__(self):
>         self.elapsed_times = {}
>
>     @pytest.hookimpl(hookwrapper=True)
>     def pytest_fixture_setup(self, fixturedef, request):
>         started = time.time()
>         yield
>         elapsed = time.time() - started
>         self.elapsed_times.setdefault(fixturedef.name, []).append(elapsed)
>
>     def pytest_terminal_summary(self, terminalreporter):
>         terminalreporter.write_sep("=", "Fixture setup times (max)")
>         for name, times in sorted(self.elapsed_times.items()):
>             tr.write_line("%s %.3f" % (name, max(times))
>
> def pytest_configure(config):
>     config.pluginmanager.register(MeasureSetupsPlugin(), 'measure_setups')
>
> You could decide to display all matter of different statistics during
> pytest_terminal_summary, like number of setups, slowest setup, etc.
>
> Hope this helps!
>
> Cheers,
> Bruno.
>
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