Root cause analysis in Testing Fundamentals - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Identifying the root cause in a bug report

You receive a bug report stating that the login button does not respond when clicked on the homepage. Which of the following is the most likely root cause?

A The user forgot their password and cannot log in.

B The button's click event handler is not attached properly in the code.

C The server is down and cannot process login requests.

D The homepage background color is not displaying correctly.

💡 Hint

Think about what directly affects the button's ability to respond to clicks.

The root cause is the missing or incorrect event handler for the button click. Other options describe symptoms or unrelated issues.

❓ Predict Output

intermediate

Output of root cause analysis log filtering

Given the following log entries, what will be the output after filtering only error-level logs?

Testing Fundamentals

logs = [
  {'level': 'info', 'message': 'User logged in'},
  {'level': 'error', 'message': 'Null pointer exception'},
  {'level': 'warning', 'message': 'Low disk space'},
  {'level': 'error', 'message': 'Timeout error'}
]

error_logs = [log['message'] for log in logs if log['level'] == 'error']
print(error_logs)

A []

B ['User logged in', 'Low disk space']

C ['Null pointer exception']

D ['Null pointer exception', 'Timeout error']

💡 Hint

Filter logs where level equals 'error'.

The list comprehension filters logs with level 'error' and extracts their messages, resulting in two error messages.

❓ assertion

advanced

Assertion to verify root cause fix in test automation

Which assertion correctly verifies that a bug causing a crash on clicking 'Submit' is fixed by checking the page does not crash?

Testing Fundamentals

def test_submit_button_does_not_crash(driver):
    driver.get('http://example.com/form')
    submit_button = driver.find_element('id', 'submit')
    submit_button.click()
    # Which assertion below is correct?

A assert submit_button.is_displayed()

B assert driver.current_url == 'http://example.com/form'

C assert 'Error' not in driver.page_source

D assert driver.find_element('id', 'error-message').is_displayed()

💡 Hint

Check that no error text appears after clicking submit.

Option C checks that the page source does not contain 'Error', indicating no crash. Other options check unrelated conditions.

🔧 Debug

advanced

Debugging flaky test due to timing issue

A test intermittently fails because it tries to click a button before it is clickable. Which fix will most reliably solve this root cause?

A Use an explicit wait to wait until the button is clickable before clicking.

B Add a fixed sleep of 5 seconds before clicking the button.

C Remove the click action from the test to avoid failure.

D Click the button twice quickly to ensure it registers.

💡 Hint

Waiting dynamically for the button state is better than fixed delays.

Explicit waits wait only as long as needed for the button to be clickable, preventing flaky failures. Fixed sleeps waste time and are unreliable.

❓ framework

expert

Root cause analysis integration in CI pipeline

In a CI pipeline, which approach best helps identify the root cause of a failing test suite after a new code push?

A Collect detailed test failure logs and screenshots, then analyze failure patterns over time.

B Only run unit tests and skip integration tests to reduce failures.

C Ignore flaky tests and rerun the pipeline until it passes.

D Run all tests in parallel without logs to save time.

💡 Hint

Detailed logs and historical data help find root causes effectively.

Collecting detailed logs and analyzing failure trends helps pinpoint root causes. Ignoring failures or skipping tests hides problems.