Performance metrics collection in Selenium Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start performance logging in Selenium.

Selenium Python

driver = webdriver.Chrome()
driver.[1]('performance')

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

Astart_log

Bstart_performance_logging

Cenable_performance

Dbegin_logging

Attempts:

3 left

💡 Hint

Common Mistakes

Using a method that does not exist like start_performance_logging.

Using enable_performance which is not a valid method.

The correct method to start performance logging is start_log('performance').

2fill in blank

medium

Complete the code to retrieve performance logs from the driver.

Selenium Python

logs = driver.get_log('[1]')

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

Abrowser

Bdriver

Cperformance

Dnetwork

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'browser' or 'network' which are different log types.

Using 'driver' which is not a valid log type.

To get performance logs, use get_log('performance').

3fill in blank

hard

Fix the error in the code to correctly parse performance logs.

Selenium Python

for entry in logs:
    message = json.loads(entry['[1]'])
    print(message)

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

Alog

Bmessage

CmessageText

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'messageText' or 'log' which do not exist in the log entry.

Using 'message' with wrong capitalization.

The correct key to access the JSON string in each log entry is 'message'.

4fill in blank

hard

Fill both blanks to filter performance logs for network events.

Selenium Python

network_events = [entry for entry in logs if '[1]' in json.loads(entry['message'])['[2]']]

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

ANetwork.responseReceived

Bmethod

Cparams

DNetwork.requestWillBeSent

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'params' instead of 'method' as the key.

Using 'Network.requestWillBeSent' which is a different event.

Filter logs where 'method' key equals 'Network.responseReceived' to get network events.

5fill in blank

hard

Fill all three blanks to extract URL, status, and timing from network response logs.

Selenium Python

for event in network_events:
    msg = json.loads(event['[1]'])
    url = msg['[2]']['response']['url']
    status = msg['[3]']['response']['status']
    print(f"URL: {url}, Status: {status}")

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

Amessage

Bparams

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'message' or 'params' inconsistently causing key errors.

Confusing the keys for JSON parsing.

The JSON string is under 'message', and the event details are under 'params'.

Practice

1. What is the main purpose of collecting performance metrics in Selenium tests?

easy

A. To check if the page layout matches the design

B. To verify the correctness of form inputs

C. To measure how fast a web page and its resources load

D. To test user login functionality

Solution

1. Step 1: Understand performance metrics

   Performance metrics focus on timing data related to page loading and resource fetching.

2. Step 2: Identify the purpose in Selenium context

   In Selenium, performance metrics help measure loading speed, not layout or input correctness.

3. Final Answer:

   To measure how fast a web page and its resources load -> Option C

4. Quick Check:

   Performance metrics = loading speed [OK]

Hint: Performance metrics = page and resource load times [OK]

Common Mistakes:

• Confusing performance metrics with UI layout checks
• Thinking performance metrics test form validation
• Assuming performance metrics check user actions

2. Which Selenium Python code snippet correctly executes JavaScript to get the navigation start time from the performance object?

easy

A. driver.execute_script('return window.performance.timing.navigationStart;')

B. driver.execute_script('window.performance.navigationStart')

C. driver.execute_script('return window.performance.navigationStart')

D. driver.execute_script('window.performance.timing.navigationStart')

Solution

1. Step 1: Identify correct JavaScript property

   The navigation start time is under window.performance.timing.navigationStart.

2. Step 2: Check correct Selenium syntax

   Use return keyword and full property path with semicolon for valid JS execution.

3. Final Answer:

   driver.execute_script('return window.performance.timing.navigationStart;') -> Option A

4. Quick Check:

   Correct JS property and return statement = driver.execute_script('return window.performance.timing.navigationStart;') [OK]

Hint: Use full path with return and semicolon in execute_script [OK]

Common Mistakes:

• Omitting 'return' keyword in execute_script
• Using wrong property path without 'timing'
• Missing semicolon causing JS errors

3. Given the following Selenium Python code snippet, what will be the output if navigationStart is 1000 and loadEventEnd is 3500?

nav_start = driver.execute_script('return window.performance.timing.navigationStart;')
load_end = driver.execute_script('return window.performance.timing.loadEventEnd;')
load_time = load_end - nav_start
print(load_time)

medium

A. 2500

B. 4500

C. 3500

D. 1000

Solution

1. Step 1: Understand the variables

   nav_start = 1000, load_end = 3500 as given.

2. Step 2: Calculate load_time

   load_time = load_end - nav_start = 3500 - 1000 = 2500.

3. Final Answer:

   2500 -> Option A

4. Quick Check:

   3500 - 1000 = 2500 [OK]

Hint: Subtract navigationStart from loadEventEnd for load time [OK]

Common Mistakes:

• Adding instead of subtracting timestamps
• Using wrong variable names
• Confusing loadEventEnd with other timing values

4. Identify the error in this Selenium Python code snippet for collecting page load time:

nav_start = driver.execute_script('return window.performance.timing.navigationStart')
load_end = driver.execute_script('return window.performance.timing.loadEventEnd')
load_time = nav_start - load_end
print(load_time)

medium

A. Variables nav_start and load_end are not defined

B. Missing semicolons in JavaScript cause syntax error

C. Using 'driver.execute_script' is incorrect for performance data

D. The subtraction order is reversed, causing negative load time

Solution

1. Step 1: Check subtraction logic

   Load time should be load_end - nav_start, not nav_start - load_end.

2. Step 2: Understand impact of reversed subtraction

   Reversed order results in negative load time, which is incorrect.

3. Final Answer:

   The subtraction order is reversed, causing negative load time -> Option D

4. Quick Check:

   Correct subtraction order = load_end - nav_start [OK]

Hint: Subtract navigationStart from loadEventEnd, not vice versa [OK]

Common Mistakes:

• Reversing subtraction causing negative results
• Assuming missing semicolons cause errors in this context
• Thinking execute_script can't get performance data

5. You want to collect multiple performance metrics in Selenium Python: navigationStart, responseStart, and loadEventEnd. Which code snippet correctly collects these and calculates the total load time from navigationStart to loadEventEnd?

hard

A. nav = driver.execute_script('window.performance.timing.navigationStart')
resp = driver.execute_script('window.performance.timing.responseStart')
load = driver.execute_script('window.performance.timing.loadEventEnd')
total_load = resp - nav
print(total_load)

B. nav = driver.execute_script('return window.performance.timing.navigationStart;')
resp = driver.execute_script('return window.performance.timing.responseStart;')
load = driver.execute_script('return window.performance.timing.loadEventEnd;')
total_load = load - nav
print(total_load)

C. nav = driver.execute_script('return window.performance.navigationStart;')
resp = driver.execute_script('return window.performance.responseStart;')
load = driver.execute_script('return window.performance.loadEventEnd;')
total_load = load - nav
print(total_load)

D. nav = driver.execute_script('return window.performance.timing.navigationStart;')
resp = driver.execute_script('return window.performance.timing.responseStart;')
load = driver.execute_script('return window.performance.timing.loadEventEnd;')
total_load = resp - load
print(total_load)

Solution

1. Step 1: Verify JavaScript property paths

   Performance timing properties are under window.performance.timing with return keyword.

2. Step 2: Check calculation logic

   Total load time is loadEventEnd minus navigationStart, so load - nav is correct.

3. Final Answer:

   nav = driver.execute_script('return window.performance.timing.navigationStart;') resp = driver.execute_script('return window.performance.timing.responseStart;') load = driver.execute_script('return window.performance.timing.loadEventEnd;') total_load = load - nav print(total_load) -> Option B

4. Quick Check:

   Correct property path and subtraction order = nav = driver.execute_script('return window.performance.timing.navigationStart;') resp = driver.execute_script('return window.performance.timing.responseStart;') load = driver.execute_script('return window.performance.timing.loadEventEnd;') total_load = load - nav print(total_load) [OK]

Hint: Use full timing path and subtract navigationStart from loadEventEnd [OK]

Common Mistakes:

• Using wrong property paths without 'timing'
• Calculating load time with wrong subtraction order
• Omitting 'return' in execute_script calls