Comparing values (equality, inequality) in PyTest - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this pytest assertion?

Consider the following pytest test function. What will be the result of running this test?

PyTest

def test_compare_values():
    a = [1, 2, 3]
    b = [1, 2, 3]
    assert a == b

A Test passes because lists have the same values in order

B Test fails because lists are different objects

C Test raises a TypeError

D Test fails because lists have different lengths

💡 Hint

In Python, equality (==) compares values, not object identity.

The assertion compares the values inside the lists. Since both lists contain the same elements in the same order, the test passes.

❓ assertion

intermediate

Which assertion correctly checks inequality of two variables?

You want to write a pytest assertion to confirm that variable x is NOT equal to variable y. Which option is correct?

A assert x <> y

B assert x != y

C assert x =! y

D assert not x == y

💡 Hint

Use the standard Python operator for inequality.

The correct operator for inequality in Python is '!='. Option B has invalid syntax, C is outdated and invalid in Python 3, and D is logically correct but less direct.

🔧 Debug

advanced

Why does this pytest assertion fail unexpectedly?

Examine the test below. Why does the assertion fail even though the printed values look equal?

PyTest

def test_string_compare():
    s1 = 'Test\n'
    s2 = 'Test\r\n'
    print(repr(s1))
    print(repr(s2))
    assert s1 == s2

A The strings differ in newline characters, so they are not equal

B The assertion fails because print changes the strings

C The test fails due to a syntax error in the assertion

D The strings are equal but the assertion is written incorrectly

💡 Hint

Look carefully at the escape characters in the strings.

The string s1 ends with a newline '\n', while s2 ends with carriage return and newline '\r\n'. These are different characters, so the strings are not equal and the assertion fails.

🧠 Conceptual

advanced

What is the difference between '==' and 'is' in Python testing?

In pytest assertions, what is the key difference between using '==' and 'is' when comparing two variables?

A '==' and 'is' are interchangeable in pytest assertions

B '==' checks object identity, 'is' checks value equality

C '==' checks value equality, 'is' checks if both variables point to the same object

D '==' checks type equality, 'is' checks value equality

💡 Hint

Think about comparing two different lists with the same content.

'==' compares if the values are equal, while 'is' checks if both variables refer to the exact same object in memory.

❓ framework

expert

Which pytest assertion will fail when comparing floating point numbers due to precision issues?

Given the following test, which assertion will fail due to floating point precision problems?

PyTest

def test_float_comparison():
    a = 0.1 + 0.2
    b = 0.3
    # Which assertion fails?

A assert abs(a - b) < 1e-9

B assert round(a, 1) == round(b, 1)

C assert a != b

D assert a == b

💡 Hint

Floating point arithmetic can cause small precision errors.

Due to floating point precision, 0.1 + 0.2 is not exactly equal to 0.3, so 'assert a == b' fails. The other assertions handle precision properly.