Single parameter in PyTest - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to parametrize the test with a single value.

PyTest

import pytest

@pytest.mark.parametrize('number', [[1]])
def test_is_positive(number):
    assert number > 0

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

A-3

B0

C5

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using zero or negative numbers which cause the test to fail.

Forgetting to put the parameter inside a list.

The test is parametrized with the value 5, which is positive, so the assertion passes.

2fill in blank

medium

Complete the code to parametrize the test with multiple values using a single parameter.

PyTest

import pytest

@pytest.mark.parametrize('value', [1, 2, [1]])
def test_is_integer(value):
    assert isinstance(value, int)

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

A3.5

BNone

C'4'

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using a float or string instead of an integer.

Not including the parameter inside the list.

The parameter list includes 1, 2, and 3, all integers, so the test passes for all.

3fill in blank

hard

Fix the error in the code by completing the parameter list correctly.

PyTest

import pytest

@pytest.mark.parametrize('item', [1])
def test_not_none(item):
    assert item is not None

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

A[1, 2, 3]

B[None, 1, 2]

C1, 2, 3

DNone

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a tuple instead of a list.

Including None which causes the test to fail.

The parameter list must be a list of values. Using [1, 2, 3] correctly passes the test.

4fill in blank

hard

Fill both blanks to parametrize the test with a single parameter and check for even numbers.

PyTest

import pytest

@pytest.mark.parametrize('[1]', [2, 4, 6, 8])
def test_is_even([2]):
    assert [2] % 2 == 0

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

Anum

Bnumber

Cvalue

Ditem

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names in the decorator and function argument.

Using names that do not match the parameter list.

Using 'num' as the parameter name in both places matches the parameterized values and the test argument.

5fill in blank

hard

Fill all three blanks to parametrize the test with a single parameter and assert it is a string.

PyTest

import pytest

@pytest.mark.parametrize('[1]', ['apple', 'banana', 'cherry'])
def test_is_string([2]):
    assert isinstance([3], str)

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

Afruit

Bitem

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names in the decorator and function argument.

Mismatching the variable name in the assertion.

The parameter name 'fruit' is used in the decorator and as the function argument. The assertion checks if 'fruit' is a string.

Practice

1. What is the purpose of using a single parameter in a pytest test function?

easy

A. To define multiple test functions at once

B. To make the test function run only once

C. To skip the test function during execution

D. To pass different values to the test function for repeated testing

Solution

1. Step 1: Understand pytest parameterization

   Pytest allows passing parameters to test functions to run the same test with different inputs.

2. Step 2: Role of a single parameter

   A single parameter lets you supply multiple values to the test, so it runs multiple times with each value.

3. Final Answer:

   To pass different values to the test function for repeated testing -> Option D

4. Quick Check:

   Single parameter = multiple test runs [OK]

Hint: Single parameter means testing with different inputs [OK]

Common Mistakes:

• Thinking single parameter defines multiple tests
• Confusing parameter with skipping tests
• Assuming single parameter runs test once only

2. Which of the following is the correct syntax to use a single parameter with pytest's @pytest.mark.parametrize decorator?

easy

A. @pytest.mark.parametrize('num', 1, 2, 3)

B. @pytest.mark.parametrize(num, [1, 2, 3])

C. @pytest.mark.parametrize('num', [1, 2, 3])

D. @pytest.mark.parametrize(['num'], 1, 2, 3)

Solution

1. Step 1: Check parameter name format

   The parameter name must be a string inside quotes, e.g., 'num'.

2. Step 2: Check values format

   The values must be inside a list or iterable, e.g., [1, 2, 3].

3. Final Answer:

   @pytest.mark.parametrize('num', [1, 2, 3]) -> Option C

4. Quick Check:

   Parametrize syntax = string + list [OK]

Hint: Parameter name in quotes, values in list brackets [OK]

Common Mistakes:

• Not quoting the parameter name
• Passing values without list brackets
• Using wrong argument structure

3. What will be the output when running this pytest code?

import pytest

@pytest.mark.parametrize('x', [2, 4])
def test_double(x):
    assert x * 2 == 4

medium

A. First test passes, second test fails

B. Both tests fail

C. First test fails, second test passes

D. Both tests pass

Solution

1. Step 1: Evaluate first test with x=2

   2 * 2 = 4, assertion is true, test passes.

2. Step 2: Evaluate second test with x=4

   4 * 2 = 8, assertion 8 == 4 is false, test fails.

3. Final Answer:

   First test passes, second test fails -> Option A

4. Quick Check:

   2*2=4 pass, 4*2=8 fail [OK]

Hint: Check each input separately for assertion [OK]

Common Mistakes:

• Assuming all tests pass without checking values
• Mixing up which input causes failure
• Ignoring assertion logic

4. Identify the error in this pytest code using a single parameter:

import pytest

@pytest.mark.parametrize('val', 1, 2, 3)
def test_positive(val):
    assert val > 0

medium

A. Parameter name should not be in quotes

B. Missing list brackets around parameter values

C. Test function must have two parameters

D. Assertion should use == instead of >

Solution

1. Step 1: Check parametrize values format

   Values must be inside a list or iterable, e.g., [1, 2, 3].

2. Step 2: Identify missing brackets

   Code passes values as separate arguments instead of a single list, causing syntax error.

3. Final Answer:

   Missing list brackets around parameter values -> Option B

4. Quick Check:

   Values need list brackets [OK]

Hint: Values must be in a list or tuple [OK]

Common Mistakes:

• Passing values without brackets
• Removing quotes from parameter name
• Wrong assertion operator

5. Given this test function, how can you modify it to test multiple string inputs using a single parameter?

def test_is_uppercase(s):
    assert s.isupper()

hard

A. Add @pytest.mark.parametrize('s', ['HELLO', 'WORLD']) above the function

B. Change function to accept two parameters s and t

C. Use a for loop inside the test to iterate over strings

D. Call test_is_uppercase multiple times manually

Solution

1. Step 1: Understand parameterizing tests

   Using @pytest.mark.parametrize allows running the test multiple times with different inputs.

2. Step 2: Apply parametrize decorator with string list

   Adding @pytest.mark.parametrize('s', ['HELLO', 'WORLD']) runs test_is_uppercase twice with each string.

3. Final Answer:

   Add @pytest.mark.parametrize('s', ['HELLO', 'WORLD']) above the function -> Option A

4. Quick Check:

   Parametrize decorator runs test with multiple inputs [OK]

Hint: Use @pytest.mark.parametrize with list of inputs [OK]

Common Mistakes:

• Trying to pass multiple parameters instead of one
• Using loops inside test instead of parametrize
• Calling test manually instead of using pytest features