First PyTest test - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to write a simple PyTest test function that checks if 2 + 2 equals 4.

PyTest

def test_addition():
    assert 2 + 2 == [1]

Drag options to blanks, or click blank then click option'

A5

B4

C3

D6

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong number like 5 or 3 causes the test to fail.

Forgetting to use assert keyword.

The test checks if 2 + 2 equals 4. Using 4 makes the assertion true, so the test passes.

2fill in blank

medium

Complete the code to write a PyTest test function that checks if the string 'hello' starts with 'h'.

PyTest

def test_startswith():
    assert 'hello'.[1]('h')

Drag options to blanks, or click blank then click option'

Acontains

Bendswith

Cstartswith

Dfind

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'endswith' checks the end, not the start.

Using 'contains' is not a string method in Python.

The startswith method checks if the string begins with the given character.

3fill in blank

hard

Fix the error in the PyTest test function that checks if the length of list [1, 2, 3] is 3.

PyTest

def test_list_length():
    assert len([1, 2, 3]) == [1]

Drag options to blanks, or click blank then click option'

A3

B4

C2

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong number like 2 or 4 causes the test to fail.

Forgetting to use len() function.

The list has three elements, so its length is 3. Using 3 makes the assertion true.

4fill in blank

hard

Fill both blanks to write a PyTest test that checks if the last character of 'world' is 'd'.

PyTest

def test_last_char():
    assert 'world'[[1]] == [2]

Drag options to blanks, or click blank then click option'

A-1

B0

C'd'

D'w'

Attempts:

3 left

💡 Hint

Common Mistakes

Using index 0 gets the first character, not the last.

Using wrong character in comparison.

Using index -1 gets the last character of the string. It should equal 'd' for the test to pass.

5fill in blank

hard

Fill all three blanks to write a PyTest test that checks if the dictionary {'a': 1, 'b': 2} has key 'a' with value 1.

PyTest

def test_dict_key_value():
    data = [1]
    assert data[[2]] == [3]

Drag options to blanks, or click blank then click option'

A{'a': 1, 'b': 2}

B'a'

C1

D{'x': 10, 'y': 20}

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong dictionary or key causes test failure.

Comparing to wrong value.

The dictionary has keys 'a' and 'b'. We check if data['a'] equals 1 for the test to pass.

Practice

1. What does PyTest look for to identify a test function?

easy

A. Functions decorated with @pytest.test

B. Functions ending with _test

C. Functions starting with test_

D. Functions containing assert keyword

Solution

1. Step 1: Understand PyTest naming convention

   PyTest automatically finds functions whose names start with test_.

2. Step 2: Compare options with PyTest rules

   Only functions starting with test_ are recognized as tests by default.

3. Final Answer:

   Functions starting with test_ -> Option C

4. Quick Check:

   PyTest test function = starts with test_ [OK]

Hint: Look for functions starting with test_ to find tests [OK]

Common Mistakes:

• Thinking functions ending with _test are tests
• Believing assert keyword alone marks a test
• Assuming decorators are needed for basic tests

2. Which of the following is the correct syntax for a simple PyTest test function?

easy

A. def add_test():\n assert 1 + 1 == 2

B. def test_add():\n assert 1 + 1 == 2

C. def test_add():\n assert 1 + 1 == 3

D. def testAdd():\n assert 1 + 1 == 2

Solution

1. Step 1: Check function name format

   PyTest requires test functions to start with test_, so test_add is correct.

2. Step 2: Verify assertion correctness

   The assertion 1 + 1 == 2 is true, so the test will pass.

3. Final Answer:

   def test_add():\n assert 1 + 1 == 2 -> Option B

4. Quick Check:

   Correct test name and true assert = def test_add():\n assert 1 + 1 == 2 [OK]

Hint: Use def test_...() with assert for valid PyTest tests [OK]

Common Mistakes:

• Naming function without test_ prefix
• Using incorrect assertion values
• Using camelCase instead of snake_case for test names

3. What will be the result when running this PyTest test?

def test_example():
    x = 5
    y = 2
    assert x - y == 3

medium

A. Test passes successfully

B. SyntaxError occurs

C. Test fails with AssertionError

D. Test is skipped automatically

Solution

1. Step 1: Evaluate the assertion expression

   Calculate x - y which is 5 - 2 = 3.

2. Step 2: Compare with asserted value

   The assertion checks if 3 == 3, which is true, so no error is raised.

3. Final Answer:

   Test passes successfully -> Option A

4. Quick Check:

   5 - 2 equals 3 means assert passes [OK]

Hint: Calculate assert expression; true means test passes [OK]

Common Mistakes:

• Assuming test fails without checking assertion
• Confusing syntax errors with assertion failures
• Thinking tests skip without skip decorators

4. Identify the error in this PyTest test function:

def test_sum():
    total = 2 + 2
    assert total = 4

medium

A. Using single equals (=) instead of double equals (==) in assert

B. Function name does not start with test_

C. Missing return statement in test function

D. Indentation error in function body

Solution

1. Step 1: Check the assert statement syntax

   The assert uses = which is assignment, not comparison. It should be ==.

2. Step 2: Confirm function name and indentation

   The function name starts with test_ and indentation is correct, so no error there.

3. Final Answer:

   Using single equals (=) instead of double equals (==) in assert -> Option A

4. Quick Check:

   Assert needs ==, not = [OK]

Hint: Use == in assert, not = for comparison [OK]

Common Mistakes:

• Using = instead of == in assert
• Thinking return is needed in test functions
• Confusing indentation errors with syntax errors

5. You want to test a function multiply(a, b) that returns the product of two numbers. Which PyTest test function correctly tests that multiply(3, 4) returns 12?

hard

A. def test_multiply():\n assert multiply(3, 4) == 7

B. def test_multiply():\n assert multiply(3, 4) = 12

C. def multiply_test():\n assert multiply(3, 4) == 12

D. def test_multiply():\n assert multiply(3, 4) == 12

Solution

1. Step 1: Verify test function name

   The function name must start with test_, so test_multiply is correct.

2. Step 2: Check assertion correctness

   The assertion must compare with == and the expected result is 12, so assert multiply(3, 4) == 12 is correct.

3. Final Answer:

   def test_multiply():\n assert multiply(3, 4) == 12 -> Option D

4. Quick Check:

   Correct name and assert with == 12 = def test_multiply():\n assert multiply(3, 4) == 12 [OK]

Hint: Test functions start with test_ and assert expected == actual [OK]

Common Mistakes:

• Wrong expected value in assert
• Wrong function name prefix
• Using = instead of == in assert