Reading test data from CSV in Selenium Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of reading CSV test data with Python csv.reader

What will be the output of this code snippet that reads a CSV file and prints each row as a list?

Selenium Python

import csv
with open('testdata.csv', newline='') as csvfile:
    reader = csv.reader(csvfile)
    for row in reader:
        print(row)

A Error: FileNotFoundError

B username,password\nuser1,pass1\nuser2,pass2

C ['username,password', 'user1,pass1', 'user2,pass2']

D [['username', 'password'], ['user1', 'pass1'], ['user2', 'pass2']]

💡 Hint

csv.reader returns each row as a list of strings.

The csv.reader reads the CSV file line by line and splits each line by commas into a list. So each printed row is a list of strings representing the columns.

❓ assertion

intermediate

Correct assertion for CSV test data length

Given a list 'data' read from a CSV file with 3 rows including header, which assertion correctly checks the number of data rows excluding the header?

Selenium Python

data = [['username', 'password'], ['user1', 'pass1'], ['user2', 'pass2']]

A assert len(data) == 2

B assert len(data[1:]) == 3

C assert len(data) - 1 == 2

D assert len(data[1:]) == 1

💡 Hint

Remember to exclude the header row when counting data rows.

The header row is the first element, so data rows are from index 1 onward. len(data) is 3, so len(data) - 1 equals 2 data rows.

❓ locator

advanced

Best locator to find username input for CSV-driven test

In a Selenium test reading usernames from CSV, which locator is best to find the username input field for entering data?

A driver.find_element(By.ID, 'username')

B driver.find_element(By.XPATH, '//input[@name="user"]')

C driver.find_element(By.CLASS_NAME, 'input-field')

D driver.find_element(By.CSS_SELECTOR, 'input[type="text"]')

💡 Hint

ID locators are unique and fast.

Using ID is the most reliable and fastest locator if the element has a unique ID attribute.

🔧 Debug

advanced

Identify error reading CSV with DictReader

What error will this code raise when reading a CSV file missing the header row?

Selenium Python

import csv
with open('testdata_noheader.csv', newline='') as csvfile:
    reader = csv.DictReader(csvfile)
    for row in reader:
        print(row['username'])

A AttributeError: 'NoneType' object has no attribute 'get'

B KeyError: 'username'

C No error, prints usernames

D FileNotFoundError

💡 Hint

DictReader uses the first row as keys by default.

If the CSV file has no header row, DictReader treats the first data row as header keys, so 'username' key is missing and accessing row['username'] raises KeyError.

❓ framework

expert

Best practice for integrating CSV test data in Selenium Python tests

Which approach best integrates CSV test data into Selenium tests for multiple login scenarios?

A Read CSV in test setup, use pytest parametrize to run test with each row

B Hardcode test data in test function, ignore CSV

C Read CSV inside each test method without reuse

D Manually copy CSV data into test assertions

💡 Hint

Use test frameworks features to run tests with multiple data sets.

Using pytest parametrize with CSV data read once in setup allows clean, reusable, and scalable tests for multiple data-driven scenarios.