You want to test a function that may raise either DeprecationWarning or UserWarning. How can you assert that exactly one warning of either type is raised during the test?

hard📝 framework Q15 of 15

PyTest - Writing Assertions

You want to test a function that may raise either DeprecationWarning or UserWarning. How can you assert that exactly one warning of either type is raised during the test?

AUse two separate with blocks for each warning type and assert one warning each

BUse a single with block with pytest.warns(Warning) and check the warning type inside

CUse pytest.warns with a tuple of warning types and assert one warning caught

DUse pytest.warns without specifying warning type and count warnings

Step-by-Step Solution

Solution:

Step 1: Understand pytest.warns supports multiple warning types
pytest.warns can accept a tuple of warning classes to catch any of those types.
Step 2: Use tuple to catch either DeprecationWarning or UserWarning
Using pytest.warns((DeprecationWarning, UserWarning)) catches either warning type in one block.
Step 3: Assert exactly one warning was caught
Inside the block, assert that one warning was raised to ensure test precision.
Final Answer:
Use pytest.warns with a tuple of warning types and assert one warning caught -> Option C
Quick Check:
Tuple of warnings in pytest.warns = D [OK]

Quick Trick: Pass tuple of warnings to pytest.warns to catch multiple types [OK]

Common Mistakes:

MISTAKES

Using multiple with blocks causing multiple warnings
Not specifying warning types and catching unrelated warnings
Assuming pytest.warns accepts multiple calls in one block

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More PyTest Quizzes

You want to test a function that may raise either DeprecationWarning or UserWarning. How can you assert that exactly one warning of either type is raised during the test?

Step 1: Understand pytest.warns supports multiple warning types

Step 2: Use tuple to catch either DeprecationWarning or UserWarning

Step 3: Assert exactly one warning was caught

Final Answer:

Quick Check:

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