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Mock out dependencies while testing in Python
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Rain
March 19, 2021
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Mock out dependencies while testing in Python
Rain
March 19, 2021
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Transcript
Mock Out External Dependencies Rain Wu
Agenda Why isolate dependencies during testing The scope of patched
object The potential risks of mocking dependencies with mock package The tricks of MagickMock
Why isolate dependencies during testing The essence of the test
Tragedies while testing without isolation When should I mock?
foo.py test_foo.py
foo.py test_foo.py Function Test Determines Reflect
foo.py test_foo.py Execute the logic Check the result Call Return
None
Sometimes you should not really execute the logic during the
test
Otherwise… Paid for your API calls Got banned because high-frequency
access Pollute the storage Execute unrecoverable operations
Lab 01 How py te st po ll u te
your s to rage while unit- te s ti ng?
None
The scope of patched object Context manager Function decorator Class
decorator Construct and destruct manually (not recommend)
Lab 02 - 1 Con te xt manager
Lab 02 - 2 Func ti on decora to r
Lab 02 - 3 Class decora to r
Construct and Destruct Manually
The Potential Risks of Mocking Dependencies Wrong parameters Misspelling methods
Lab 03 - 1 Th e unit te st was
passed accidenta ll y (but maybe you th ink th at it should be like th is )
Lab 03 - 2 In some cases, mock wi ll
catch th e issues for you au to ma ti ca ll y
Lab 03 - 3 But some ti mes it won’t,
so we had be tt er make th e schema of patched object s tr ic te r by ourselves
The Tricks of MagicMock Object attributes
Lab 04 - 1 Th e valid a tt ribu
te s of a MagicMock object
Lab 04 - 2 Apply th e fi xed a
tt ribu te s recursively via th e au to spec kwarg
Thanks