Checking membership (in, not in) in PyTest - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if 'apple' is in the fruits list.

PyTest

def test_apple_in_fruits():
    fruits = ['apple', 'banana', 'cherry']
    assert 'apple' [1] fruits

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

Ain

B!=

C==

Dnot in

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'not in' instead of 'in' will fail the test.

The in keyword checks if an item is present in a list. Here, 'apple' should be in the fruits list, so in is correct.

2fill in blank

medium

Complete the code to check that 'grape' is not in the fruits list.

PyTest

def test_grape_not_in_fruits():
    fruits = ['apple', 'banana', 'cherry']
    assert 'grape' [1] fruits

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

Ain

B==

Cnot in

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'in' instead of 'not in' will cause the test to fail.

The not in keyword checks that an item is not present in a list. Since 'grape' is not in fruits, not in is correct.

3fill in blank

hard

Fix the error in the assertion to check if 'banana' is in the fruits list.

PyTest

def test_banana_in_fruits():
    fruits = ['apple', 'banana', 'cherry']
    assert 'banana' [1] fruits

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

A==

Bnot in

C!=

Din

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'not in' will cause the test to fail incorrectly.

The assertion should check if 'banana' is present in the list using in. Using not in or other operators is incorrect here.

4fill in blank

hard

Fill both blanks to create a test that checks if 'orange' is not in the fruits list and 'cherry' is in the fruits list.

PyTest

def test_fruits_membership():
    fruits = ['apple', 'banana', 'cherry']
    assert 'orange' [1] fruits
    assert 'cherry' [2] fruits

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

Anot in

B==

Cin

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up 'in' and 'not in' keywords.

The first assertion checks that 'orange' is not in the list, so not in is correct. The second checks that 'cherry' is in the list, so in is correct.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that includes only fruits that are in the allowed list.

PyTest

def test_allowed_fruits():
    fruits = ['apple', 'banana', 'cherry', 'date']
    allowed = ['banana', 'date', 'fig']
    filtered = {fruit: True for fruit in fruits if fruit [1] allowed and fruit [2] 'apple' and fruit [3] 'fig'}
    assert 'banana' in filtered
    assert 'apple' not in filtered
    assert 'fig' not in filtered

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

Ain

Bnot in

C!=

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using not in instead of != for string comparisons.

The comprehension includes fruits that are in the allowed list (in), but excludes 'apple' and 'fig' by checking they are not equal to those strings using !=. Using not in would be incorrect here because 'apple' and 'fig' are strings, not collections.

Practice

1. Which of the following statements correctly checks if the string 'apple' is in the list fruits = ['apple', 'banana', 'cherry'] using pytest assertions?

easy

A. assert fruits in 'apple'

B. assert 'apple' not in fruits

C. assert 'apple' in fruits

D. assert 'apple' == fruits

Solution

1. Step 1: Understand the membership check

   The in keyword checks if an item exists inside a collection like a list.

2. Step 2: Apply the correct assertion

   To confirm 'apple' is in the list, use assert 'apple' in fruits. This passes if 'apple' is found.

3. Final Answer:

   assert 'apple' in fruits -> Option C

4. Quick Check:

   Use in to check presence [OK]

Hint: Use 'in' to check presence, 'not in' for absence [OK]

Common Mistakes:

• Using 'not in' instead of 'in' when checking presence
• Reversing the order like 'fruits in apple'
• Using equality instead of membership check

2. Which of the following is the correct syntax to assert that the number 5 is NOT in the list numbers = [1, 2, 3, 4] using pytest?

easy

A. assert 5 in numbers

B. assert numbers not in 5

C. assert 5 not numbers

D. assert 5 not in numbers

Solution

1. Step 1: Identify the correct membership operator

   To check that 5 is not in the list, use not in keyword.

2. Step 2: Write the correct assertion syntax

   The correct syntax is assert 5 not in numbers. This passes if 5 is absent.

3. Final Answer:

   assert 5 not in numbers -> Option D

4. Quick Check:

   Use 'not in' to check absence [OK]

Hint: Remember 'not in' checks absence, syntax: assert x not in y [OK]

Common Mistakes:

• Misplacing 'not' like 'assert 5 not numbers' (SyntaxError)
• Swapping operands like 'numbers not in 5' which is invalid
• Using 'in' instead of 'not in' for absence check

3. What will be the result of this pytest assertion?

items = ['pen', 'pencil', 'eraser']
assert 'marker' not in items

medium

A. Test passes because 'marker' is not in the list

B. Test fails because 'marker' is in the list

C. SyntaxError due to wrong assertion

D. Test passes because 'marker' is in the list

Solution

1. Step 1: Check if 'marker' is in the list

   The list contains 'pen', 'pencil', and 'eraser'. 'marker' is not present.

2. Step 2: Evaluate the assertion

   The assertion checks that 'marker' is not in items, which is true, so the test passes.

3. Final Answer:

   Test passes because 'marker' is not in the list -> Option A

4. Quick Check:

   Not in list means assertion passes [OK]

Hint: If item absent and 'not in' used, test passes [OK]

Common Mistakes:

• Assuming test fails if item is missing
• Confusing 'in' and 'not in' logic
• Thinking syntax error occurs with 'not in'

4. Identify the error in this pytest assertion and select the correct fix:

colors = ['red', 'green', 'blue']
assert 'yellow' in colors not

medium

A. Use 'assert not 'yellow' in colors' instead

B. SyntaxError: 'not' should come before 'in' as 'not in'

C. Replace 'in' with 'not in' and remove 'not' at the end

D. No error, assertion is correct

Solution

1. Step 1: Analyze the assertion syntax

   The expression ends with 'colors not' which is invalid syntax in Python.

2. Step 2: Correct the membership operator usage

   The correct operator for checking absence is 'not in', written together, not separated.

3. Final Answer:

   SyntaxError: 'not' should come before 'in' as 'not in' -> Option B

4. Quick Check:

   Use 'not in' together, no trailing 'not' [OK]

Hint: Write 'not in' together, never split or reorder [OK]

Common Mistakes:

• Writing 'in colors not' instead of 'not in colors'
• Using 'assert colors not in 'yellow'' which reverses order
• Omitting 'not' or placing it incorrectly

5. You want to write a pytest test to confirm that none of the forbidden words ['spam', 'scam', 'fraud'] appear in the user input string text. Which assertion correctly checks this?

hard

A. assert all(word not in text for word in ['spam', 'scam', 'fraud'])

B. assert any(word in text for word in ['spam', 'scam', 'fraud'])

C. assert 'spam' not in text and 'scam' not in text or 'fraud' not in text

D. assert 'spam' in text or 'scam' in text or 'fraud' in text

Solution

1. Step 1: Understand the requirement

   We want to ensure none of the forbidden words appear in the text, so all must be absent.

2. Step 2: Use a generator with 'all' and 'not in'

   The expression all(word not in text for word in forbidden_words) returns True only if every word is not in text.

3. Step 3: Evaluate other options

   assert any(word in text for word in ['spam', 'scam', 'fraud']) checks if any forbidden word is present (opposite). assert 'spam' not in text and 'scam' not in text or 'fraud' not in text has incorrect logic mixing 'and' and 'or'. assert 'spam' in text or 'scam' in text or 'fraud' in text checks presence, not absence.

4. Final Answer:

   assert all(word not in text for word in ['spam', 'scam', 'fraud']) -> Option A

5. Quick Check:

   Use all() with 'not in' for absence of all items [OK]

Hint: Use all() with 'not in' to confirm all items absent [OK]

Common Mistakes:

• Using any() instead of all() for absence check
• Mixing 'and' and 'or' incorrectly in conditions
• Checking only one forbidden word instead of all