Checking membership (in, not in) in PyTest - Test Execution Trace

Test Overview

This test checks if certain items are present or absent in a list using Python's in and not in operators. It verifies membership conditions with assertions.

Test Code - pytest

PyTest

import pytest

def test_membership():
    fruits = ['apple', 'banana', 'cherry']
    # Check if 'banana' is in the list
    assert 'banana' in fruits
    # Check if 'orange' is not in the list
    assert 'orange' not in fruits

Execution Trace - 5 Steps

Step	Action	System State	Assertion	Result
1	Test starts	pytest test runner initialized	-	PASS
2	Defines list fruits with ['apple', 'banana', 'cherry']	List fruits created in memory	-	PASS
3	Checks if 'banana' is in fruits using assert 'banana' in fruits	Evaluates membership condition	'banana' is found in fruits list	PASS
4	Checks if 'orange' is not in fruits using assert 'orange' not in fruits	Evaluates membership condition	'orange' is not found in fruits list	PASS
5	Test ends successfully	All assertions passed	-	PASS

Failure Scenario

Failing Condition: 'banana' is missing from the fruits list or 'orange' is present in the list

Execution Trace Quiz - 3 Questions

What does the assertion 'assert "banana" in fruits' verify?

A fruits list is empty

B "banana" is not in the fruits list

C "banana" is an element of the fruits list

D fruits list contains only "banana"

Key Result

Use simple membership assertions with 'in' and 'not in' to verify presence or absence of items in collections. This makes tests clear and easy to understand.