Reading test data from JSON in Selenium Python

Introduction

We use JSON files to keep test data separate from test code. This helps us change data easily without touching the test steps.

When you want to test a website with different user names and passwords.

When you need to run the same test with many sets of data.

When you want to keep your test data organized and easy to update.

When sharing test data with other team members or tools.

When you want to avoid hardcoding values inside your test scripts.

Syntax

Selenium Python

import json

with open('data.json') as file:
    data = json.load(file)

# Access data like this:
username = data['username']
password = data['password']

Use json.load() to read JSON data from a file.

Make sure the JSON file is in the correct folder or provide the full path.

Examples

This reads a JSON file named user_data.json and prints the email value.

Selenium Python

import json

with open('user_data.json') as f:
    user = json.load(f)

print(user['email'])

This example loads a config file and prints the URL to test.

Selenium Python

import json

with open('config.json') as f:
    config = json.load(f)

url = config['url']
print(f"Testing URL: {url}")

Sample Program

This script reads login data from testdata.json, opens a browser, enters the data, clicks login, and checks if login succeeded.

Selenium Python

import json
from selenium import webdriver
from selenium.webdriver.common.by import By

# Load test data from JSON file
def load_test_data(filename):
    with open(filename) as file:
        return json.load(file)

# Test function using Selenium and JSON data
def test_login():
    data = load_test_data('testdata.json')
    driver = webdriver.Chrome()
    driver.get(data['url'])

    # Find username and password fields and enter data
    driver.find_element(By.ID, 'username').send_keys(data['username'])
    driver.find_element(By.ID, 'password').send_keys(data['password'])

    # Click login button
    driver.find_element(By.ID, 'loginBtn').click()

    # Check if login was successful by looking for logout button
    logout_button = driver.find_element(By.ID, 'logoutBtn')
    assert logout_button.is_displayed(), 'Login failed!'

    driver.quit()

# Run the test
if __name__ == '__main__':
    test_login()

Important Notes

Always close the browser after the test to free resources.

Keep your JSON file simple and well-structured for easy reading.

Use meaningful keys in JSON to avoid confusion.

Summary

Reading test data from JSON helps separate data from code.

Use Python's json module to load data easily.

This makes tests easier to maintain and reuse with different data.

Practice

1. What is the main benefit of reading test data from a JSON file in Selenium Python tests?

easy

A. It encrypts test data for security.

B. It makes tests run faster by avoiding web interactions.

C. It automatically generates test cases without writing code.

D. It keeps test code clean and makes data easy to update without changing code.

Solution

1. Step 1: Understand test data separation

   Reading test data from JSON separates data from test logic, making code cleaner.

2. Step 2: Recognize flexibility advantage

   Updating test data in JSON does not require changing test scripts, improving flexibility.

3. Final Answer:

   It keeps test code clean and makes data easy to update without changing code. -> Option D

4. Quick Check:

   Data separation = Clean code + Easy updates [OK]

Hint: Separate data from code for easy updates [OK]

Common Mistakes:

• Thinking JSON speeds up test execution
• Believing JSON auto-generates tests
• Confusing data storage with encryption

2. Which Python code snippet correctly reads a JSON file named data.json into a variable test_data?

easy

A. import json
test_data = json.load(open('data.json'))

B. test_data = open('data.json').read()

C. import json
test_data = json.loads('data.json')

D. test_data = json.read('data.json')

Solution

1. Step 1: Identify correct json module usage

   The json.load() function reads JSON from a file object, so open() must be passed to json.load().

2. Step 2: Check syntax correctness

   import json test_data = json.load(open('data.json')) correctly imports json and uses json.load(open('data.json')) to read the file.

3. Final Answer:

   import json\ntest_data = json.load(open('data.json')) -> Option A

4. Quick Check:

   json.load + open(file) = correct JSON read [OK]

Hint: Use json.load() with open() for files [OK]

Common Mistakes:

• Using json.loads() on filename string
• Forgetting to import json module
• Calling non-existent json.read() function

3. Given the JSON file user.json with content:

{"username": "testuser", "password": "pass123"}

and the code:

import json
with open('user.json') as f:
    data = json.load(f)
print(data['username'])

What will be the output?

medium

A. {'username': 'testuser', 'password': 'pass123'}

B. pass123

C. testuser

D. KeyError

Solution

1. Step 1: Load JSON data into dictionary

   The json.load(f) reads the JSON file and converts it into a Python dictionary with keys 'username' and 'password'.

2. Step 2: Access dictionary value by key

   data['username'] accesses the value 'testuser' from the dictionary.

3. Final Answer:

   testuser -> Option C

4. Quick Check:

   data['username'] = 'testuser' [OK]

Hint: Access JSON keys like dictionary keys [OK]

Common Mistakes:

• Printing the whole dictionary instead of key value
• Using wrong key causing KeyError
• Confusing json.load() with json.loads()

4. What is wrong with this code snippet that reads JSON test data?

import json
file = open('data.json')
data = json.load(file)
file.close()
print(data['email'])

Assuming data.json does not contain the key email.

medium

A. The code will raise a KeyError because 'email' key is missing.

B. The print statement syntax is incorrect.

C. The file is not closed properly.

D. json.load() cannot read from open file objects.

Solution

1. Step 1: Understand json.load() behavior

   json.load() correctly reads JSON from an open file object, so no error here.

2. Step 2: Identify missing key issue

   Accessing data['email'] when 'email' key is missing causes a KeyError at runtime.

3. Final Answer:

   The code will raise a KeyError because 'email' key is missing. -> Option A

4. Quick Check:

   Missing key access = KeyError [OK]

Hint: Check keys exist before accessing JSON data [OK]

Common Mistakes:

• Thinking json.load() fails on open files
• Ignoring possible missing keys in JSON
• Assuming file.close() is missing or wrong

5. You want to use JSON test data to fill a login form in Selenium Python. The JSON file login.json contains:

{"username": "user1", "password": "pass1"}

Which code snippet correctly reads the JSON and uses Selenium to fill the form fields with ids user and pass?

hard

A. import json
with open('login.json') as f:
data = json.load(f)
driver.find_element_by_name('user').send_keys(data['username'])
driver.find_element_by_name('pass').send_keys(data['password'])

B. import json
with open('login.json') as f:
data = json.load(f)
driver.find_element('id', 'user').send_keys(data['username'])
driver.find_element('id', 'pass').send_keys(data['password'])

C. import json
with open('login.json') as f:
data = json.loads(f)
driver.find_element_by_id('user').send_keys(data['username'])
driver.find_element_by_id('pass').send_keys(data['password'])

D. import json
with open('login.json') as f:
data = json.load(f)
driver.find_element('name', 'user').send_keys(data['username'])
driver.find_element('name', 'pass').send_keys(data['password'])

Solution

1. Step 1: Correctly read JSON file

   json.load(f) reads JSON from file object correctly; json.loads() expects a string, so import json with open('login.json') as f: data = json.loads(f) driver.find_element_by_id('user').send_keys(data['username']) driver.find_element_by_id('pass').send_keys(data['password']) is wrong.

2. Step 2: Use correct Selenium locator method

   driver.find_element('id', 'user') is the modern syntax to find element by id; find_element_by_id() is deprecated.

3. Step 3: Match locators with element ids

   The form fields have ids 'user' and 'pass', so locating by id is correct, not by name.

4. Final Answer:

   import json with open('login.json') as f: data = json.load(f) driver.find_element('id', 'user').send_keys(data['username']) driver.find_element('id', 'pass').send_keys(data['password']) -> Option B

5. Quick Check:

   json.load + find_element('id', ...) = correct usage [OK]

Hint: Use json.load() and find_element('id', ...) for form filling [OK]

Common Mistakes:

• Using json.loads() on file object
• Using deprecated find_element_by_id()
• Using wrong locator type (name instead of id)