Custom wait conditions in Selenium Python - Test Execution Trace

Test Overview

This test uses a custom wait condition to wait until a specific element's text changes to the expected value before proceeding. It verifies that the text update happens within the timeout.

Test Code - Selenium

Selenium Python

from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from selenium.common.exceptions import TimeoutException

class text_to_be_updated:
    def __init__(self, locator, text):
        self.locator = locator
        self.text = text

    def __call__(self, driver):
        element = driver.find_element(*self.locator)
        if element.text == self.text:
            return element
        else:
            return False


def test_custom_wait_condition():
    driver = webdriver.Chrome()
    driver.get("https://example.com/dynamic_text")

    locator = (By.ID, "status")
    wait = WebDriverWait(driver, 10)

    try:
        element = wait.until(text_to_be_updated(locator, "Complete"))
        assert element.text == "Complete"
    except TimeoutException:
        assert False, "Text did not update to 'Complete' within 10 seconds"
    finally:
        driver.quit()

Execution Trace - 6 Steps

Step	Action	System State	Assertion	Result
1	Test starts and Chrome browser opens	Browser window is open with no page loaded	—	PASS
2	Browser navigates to https://example.com/dynamic_text	Page with element id='status' is loading dynamic text	—	PASS
3	WebDriverWait starts waiting up to 10 seconds for element with id='status' text to become 'Complete'	Element with id='status' initially shows different text (e.g., 'Loading...')	Check if element.text == 'Complete'	PASS
4	Custom wait condition __call__ method repeatedly checks element text	Element text changes from 'Loading...' to 'Complete' within timeout	Element text equals 'Complete'	PASS
5	Assertion verifies element.text is 'Complete'	Element text is 'Complete' as expected	assert element.text == 'Complete'	PASS
6	Browser closes and test ends	Browser window closed	—	PASS

Failure Scenario

Failing Condition: Element text does not change to 'Complete' within 10 seconds

Execution Trace Quiz - 3 Questions

What does the custom wait condition check for?

A Element is visible

B Element is clickable

C Element's text equals 'Complete'

D Page title contains 'Complete'

Key Result

Using custom wait conditions lets you wait for very specific states, like text changes, improving test reliability for dynamic content.

Practice

1. What is the main purpose of creating a custom wait condition in Selenium with Python?

easy

A. To automatically retry failed tests

B. To speed up the test execution by skipping waits

C. To replace the WebDriverWait class completely

D. To wait for a specific condition that is not covered by built-in waits

Solution

1. Step 1: Understand built-in waits limitations

   Built-in waits cover common cases but sometimes you need to wait for a unique condition.

2. Step 2: Purpose of custom wait

   Custom waits let you define exactly what to wait for, improving test reliability.

3. Final Answer:

   To wait for a specific condition that is not covered by built-in waits -> Option D

4. Quick Check:

   Custom wait = wait for unique condition [OK]

Hint: Custom waits handle unique conditions not in built-in waits [OK]

Common Mistakes:

• Thinking custom waits speed up tests
• Believing custom waits replace WebDriverWait
• Assuming custom waits retry tests automatically

2. Which of the following is the correct way to define a custom wait condition class in Selenium Python?

easy

A. class MyWait:
def __call__(self, driver):
return driver.find_element_by_id('myid')

B. class MyWait:
def wait(self):
return True

C. def MyWait(driver):
return driver.find_element('id', 'myid')

D. class MyWait:
def wait_for(self, driver):
return False

Solution

1. Step 1: Identify the special method for custom waits

   Custom wait classes must implement the __call__ method to be callable by WebDriverWait.

2. Step 2: Check method signature and return

   Method __call__ takes driver and returns element or True when condition met.

3. Final Answer:

   class MyWait:\n def __call__(self, driver):\n return driver.find_element_by_id('myid') -> Option A

4. Quick Check:

   Custom wait uses __call__ method [OK]

Hint: Custom wait class must have __call__(self, driver) method [OK]

Common Mistakes:

• Using method named wait instead of __call__
• Defining function instead of class
• Using wrong method signature

3. Given the code below, what will be the output if the element with id 'submit' appears after 3 seconds?

from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.common.by import By

class WaitForSubmit:
    def __call__(self, driver):
        try:
            elem = driver.find_element(By.ID, 'submit')
            return elem
        except:
            return False

wait = WebDriverWait(driver, 5)
submit_button = wait.until(WaitForSubmit())
print(submit_button.tag_name)

medium

A. Prints False

B. Raises TimeoutException immediately

C. Prints the tag name of the 'submit' element after waiting

D. Raises NoSuchElementException

Solution

1. Step 1: Understand the custom wait behavior

   The custom wait tries to find element with id 'submit'. If not found, returns False to keep waiting.

2. Step 2: Analyze wait.until with timeout 5 seconds

   The element appears after 3 seconds, so wait.until returns the element before timeout.

3. Final Answer:

   Prints the tag name of the 'submit' element after waiting -> Option C

4. Quick Check:

   Element appears before timeout, so tag_name prints [OK]

Hint: Custom wait returns element or False; wait.until waits until element found [OK]

Common Mistakes:

• Assuming immediate TimeoutException
• Expecting print of False instead of element
• Confusing exceptions raised

4. Identify the error in the following custom wait condition code:

class WaitForText:
    def __call__(self, driver):
        element = driver.find_element(By.ID, 'message')
        if element.text == 'Done':
            return True
        else:
            return None

wait = WebDriverWait(driver, 10)
wait.until(WaitForText())

medium

A. Returning None instead of False causes wait.until to stop waiting

B. Missing import for By causes NameError

C. Returning True instead of element causes error

D. Using find_element instead of find_elements causes exception

Solution

1. Step 1: Check imports

   The code uses By.ID but does not import By, causing NameError at runtime.

2. Step 2: Analyze return values

   Returning True or None is allowed; wait.until treats True as success and None as failure to continue waiting.

3. Final Answer:

   Missing import for By causes NameError -> Option B

4. Quick Check:

   By must be imported to avoid NameError [OK]

Hint: Always import By before using it in locators [OK]

Common Mistakes:

• Thinking None stops waiting (it continues)
• Assuming returning True causes error
• Confusing find_element with find_elements

5. You want to wait until a button with id 'start' is both visible and enabled before clicking it. Which custom wait condition class correctly implements this?

hard

A. class WaitForStart:
def __call__(self, driver):
btn = driver.find_element(By.ID, 'start')
if btn.is_displayed() and btn.is_enabled():
return btn
return False

B. class WaitForStart:
def __call__(self, driver):
btn = driver.find_element(By.ID, 'start')
if btn.is_displayed() or btn.is_enabled():
return True
return False

C. class WaitForStart:
def __call__(self, driver):
btn = driver.find_element(By.ID, 'start')
if btn.is_displayed() and btn.is_enabled():
return True
return False

D. class WaitForStart:
def __call__(self, driver):
btn = driver.find_element(By.ID, 'start')
if btn.is_enabled():
return btn
return None

Solution

1. Step 1: Check condition logic

   We need both visible and enabled, so use 'and' operator to check both.

2. Step 2: Return element when condition met

   Return the button element so wait.until returns it for further actions.

3. Final Answer:

   class WaitForStart:\n def __call__(self, driver):\n btn = driver.find_element(By.ID, 'start')\n if btn.is_displayed() and btn.is_enabled():\n return btn\n return False -> Option A

4. Quick Check:

   Return element when visible and enabled [OK]

Hint: Return element only if visible AND enabled, else False [OK]

Common Mistakes:

• Using 'or' instead of 'and' for conditions
• Returning True instead of element
• Returning None instead of False