Custom expected conditions in Selenium Python - Test Execution Trace

Test Overview

This test uses a custom expected condition to wait until a button's text changes to "Ready" before clicking it. It verifies that the button is clickable only after the text update.

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

class button_text_to_be:
    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_button_text_change_and_click():
    driver = webdriver.Chrome()
    driver.get("https://example.com/buttonpage")

    wait = WebDriverWait(driver, 10)
    button_locator = (By.ID, "start-button")

    # Wait until button text changes to 'Ready'
    button = wait.until(button_text_to_be(button_locator, "Ready"))

    button.click()

    # Verify some result after click
    result_element = driver.find_element(By.ID, "result")
    assert result_element.text == "Success"

    driver.quit()

Execution Trace - 6 Steps

Step	Action	System State	Assertion	Result
1	Test starts and Chrome browser opens	Browser window is open, ready to navigate	—	PASS
2	Navigates to https://example.com/buttonpage	Page with a button having ID 'start-button' is loaded	—	PASS
3	Waits until button text changes to 'Ready' using custom expected condition	Button initially shows 'Start', then changes to 'Ready' within 10 seconds	Checks if button text equals 'Ready'	PASS
4	Clicks the button after text is 'Ready'	Button is clickable and clicked	—	PASS
5	Finds element with ID 'result' to verify outcome	Result element is present on page	Asserts that result element text is 'Success'	PASS
6	Test ends and browser closes	Browser window is closed	—	PASS

Failure Scenario

Failing Condition: Button text does not change to 'Ready' within 10 seconds

Execution Trace Quiz - 3 Questions

What does the custom expected condition 'button_text_to_be' check?

A If the button's text matches the expected text

B If the button is visible on the page

C If the button is enabled for clicking

D If the button's color changes

Key Result

Creating custom expected conditions helps wait for specific states or changes and return useful objects like the element itself (unlike built-in text_to_be which returns True), making tests more reliable and clear.

Practice

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

easy

A. To change the browser window size automatically

B. To speed up the browser loading time

C. To wait for a specific condition that is not covered by built-in expected conditions

D. To generate test reports automatically

Solution

1. Step 1: Understand built-in expected conditions

   Built-in expected conditions cover common waits like element visibility or clickability.

2. Step 2: Identify the need for custom conditions

   When a specific wait is not available, custom expected conditions let you define exactly what to wait for.

3. Final Answer:

   To wait for a specific condition that is not covered by built-in expected conditions -> Option C

4. Quick Check:

   Custom expected conditions = wait for custom needs [OK]

Hint: Custom conditions handle waits built-ins can't cover [OK]

Common Mistakes:

• Thinking custom conditions speed up browser loading
• Confusing custom conditions with browser resizing
• Assuming custom conditions generate reports

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

easy

A. class MyCondition:
def __call__(self, driver):
return driver.title == 'Home'

B. def MyCondition(driver):
return driver.title == 'Home'

C. class MyCondition:
def call(self, driver):
return driver.title == 'Home'

D. class MyCondition:
def __init__(self, driver):
return driver.title == 'Home'

Solution

1. Step 1: Recall the special method for callable classes

   The method __call__ makes an instance callable like a function.

2. Step 2: Check method signature and return

   The __call__ method takes driver and returns a boolean or element to wait for.

3. Final Answer:

   class MyCondition:\n def __call__(self, driver):\n return driver.title == 'Home' -> Option A

4. Quick Check:

   Custom condition class needs __call__ method [OK]

Hint: Use __call__ method to make class callable [OK]

Common Mistakes:

• Using call instead of __call__ method
• Defining __init__ to return a value
• Defining a function instead of a class

3. Given this custom expected condition class, what will WebDriverWait(driver, 10).until(MyCondition()) return if the page title is 'Dashboard'?

class MyCondition:
    def __call__(self, driver):
        if driver.title == 'Dashboard':
            return True
        else:
            return False

medium

A. It will raise a TimeoutException immediately

B. It will return the driver object

C. It will return False immediately without waiting

D. It will wait until the title is 'Dashboard' and then return True

Solution

1. Step 1: Understand WebDriverWait with custom condition

   WebDriverWait calls the condition repeatedly until it returns a truthy value or timeout.

2. Step 2: Analyze the condition's return value

   If the title is 'Dashboard', __call__ returns True, so wait ends and returns True.

3. Final Answer:

   It will wait until the title is 'Dashboard' and then return True -> Option D

4. Quick Check:

   Condition returns True -> wait ends successfully [OK]

Hint: Wait ends when condition returns True [OK]

Common Mistakes:

• Thinking it raises TimeoutException immediately
• Assuming it returns False immediately
• Confusing return value with driver object

4. Identify the error in this custom expected condition class:

class ElementHasText:
    def __call__(self, driver):
        element = driver.find_element(By.ID, 'msg')
        if element.text:
            return element.text
        else:
            return False

medium

A. Missing import for By from selenium.webdriver.common.by

B. The __call__ method should return True or False only, not text

C. The class should inherit from WebDriverWait

D. The find_element method should be find_elements

Solution

1. Step 1: Check usage of By.ID in the code

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

2. Step 2: Verify other parts of the code

   Returning element.text is valid for expected conditions; inheritance from WebDriverWait is not required.

3. Final Answer:

   Missing import for By from selenium.webdriver.common.by -> Option A

4. Quick Check:

   Using By requires importing it first [OK]

Hint: Always import By before using it [OK]

Common Mistakes:

• Assuming __call__ must return only True/False
• Thinking class must inherit WebDriverWait
• Confusing find_element with find_elements

5. You want to create a custom expected condition that waits until an element with ID 'status' has text containing the word 'Complete'. Which of these implementations is correct and efficient?

hard

A. class StatusComplete:
def __call__(self, driver):
element = driver.find_element(By.ID, 'status')
return element.text.startswith('Complete')

B. class StatusComplete:
def __call__(self, driver):
element = driver.find_element(By.ID, 'status')
return 'Complete' in element.text

C. class StatusComplete:
def __call__(self, driver):
element = driver.find_element(By.ID, 'status')
if element.text == 'Complete':
return True
else:
return False

D. class StatusComplete:
def __call__(self, driver):
element = driver.find_element(By.ID, 'status')
return element.text != ''

Solution

1. Step 1: Understand the requirement

   We want to wait until the text contains the word 'Complete' anywhere inside.

2. Step 2: Analyze each option's condition

   class StatusComplete: def __call__(self, driver): element = driver.find_element(By.ID, 'status') return 'Complete' in element.text checks if 'Complete' is in element.text, which matches the requirement exactly and returns a boolean.

3. Step 3: Compare other options

   class StatusComplete: def __call__(self, driver): element = driver.find_element(By.ID, 'status') if element.text == 'Complete': return True else: return False checks exact equality, which is too strict. class StatusComplete: def __call__(self, driver): element = driver.find_element(By.ID, 'status') return element.text.startswith('Complete') checks startswith, which is partial. class StatusComplete: def __call__(self, driver): element = driver.find_element(By.ID, 'status') return element.text != '' only checks non-empty text, which is too broad.

4. Final Answer:

   class StatusComplete:\n def __call__(self, driver):\n element = driver.find_element(By.ID, 'status')\n return 'Complete' in element.text -> Option B

5. Quick Check:

   Use 'in' to check substring presence [OK]

Hint: Use 'in' operator to check substring in text [OK]

Common Mistakes:

• Checking exact equality instead of substring
• Using startswith instead of contains
• Checking only for non-empty text