Basic assert statement in PyTest - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the assert statement in pytest?

The assert statement checks if a condition is true. If it is false, the test fails and pytest shows an error.

beginner

How does pytest report a failed assert statement?

Pytest shows the exact expression that failed and the values involved, helping you understand why the test failed.

beginner

Write a simple pytest assert statement to check if 5 is greater than 3.

def test_greater():
    assert 5 > 3

This test will pass because 5 is indeed greater than 3.

intermediate

Can assert statements include messages? How?

Yes, you can add a message after a comma to explain the failure.<br>

assert x == 10, "x should be 10"

beginner

Why is using assert better than printing values for testing?

Because assert automatically fails the test if the condition is false, making tests clear and automated without manual checks.

What happens if an assert condition is false in pytest?

A The program crashes immediately

B The test passes silently

C The test fails and pytest shows an error

D Nothing happens, it continues

If the assert condition is false, pytest marks the test as failed and shows the error details.

Which of these is a valid assert statement in pytest?

A assert 2 + 2 == 4

B assert(2 + 2 = 4)

C assert 2 + 2 equals 4

D assert 2 + 2 == '4'

Option A uses correct syntax and logic. Option B has wrong syntax, A is not valid Python, D compares int to string.

How can you add a custom message to an assert statement?

A assert x == 5 then print "x should be 5"

B assert x == 5: "x should be 5"

C assert(x == 5 message "x should be 5")

D assert x == 5, "x should be 5"

You add a message after a comma in the assert statement to explain failure.

What does pytest show when an assert fails?

A A success message

B The failed expression and its values

C No output at all

D Only 'Test failed' message

Pytest shows the exact expression that failed and the values involved to help debugging.

Why is using assert statements important in automated testing?

A They automatically check conditions and fail tests if needed

B They print values for manual checking

C They slow down the test execution

D They are only for debugging, not testing

Assert statements make tests automatic by checking conditions and failing tests when conditions are false.

Explain how the assert statement works in pytest and why it is useful.

Think about how assert helps catch errors automatically.

Write a simple pytest test function using assert to check if a number is positive.

Use assert with a condition like x > 0 inside a function starting with test_