XPath with contains and starts-with in Selenium Python - Build an Automation Script

Verify login button using XPath with contains and starts-with

Preconditions (1)

Step 1: Locate the login button using XPath with contains() on the class attribute

Step 2: Verify the login button is visible and enabled

Step 3: Locate the login button using XPath with starts-with() on the id attribute

Step 4: Verify the login button text is 'Log In'

✅ Expected Result: The login button is found using both XPath expressions, is visible, enabled, and has the text 'Log In'

Automation Requirements - Selenium with Python

Assertions Needed:

Assert the login button is displayed

Assert the login button is enabled

Assert the login button text equals 'Log In'

Best Practices:

Use explicit waits to wait for elements to be visible

Use By.XPATH with contains() and starts-with() functions correctly

Avoid hardcoded sleeps

Use clear and maintainable locators

Automated Solution

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

# Setup WebDriver (assuming chromedriver is in PATH)
driver = webdriver.Chrome()
wait = WebDriverWait(driver, 10)

try:
    # Open login page
    driver.get('https://example.com/login')

    # Locate login button using contains() on class attribute
    login_button_contains = wait.until(
        EC.visibility_of_element_located(
            (By.XPATH, "//button[contains(@class, 'login-btn')]")
        )
    )

    # Assert button is displayed and enabled
    assert login_button_contains.is_displayed(), "Login button (contains) is not displayed"
    assert login_button_contains.is_enabled(), "Login button (contains) is not enabled"

    # Locate login button using starts-with() on id attribute
    login_button_starts = wait.until(
        EC.visibility_of_element_located(
            (By.XPATH, "//button[starts-with(@id, 'loginBtn')]")
        )
    )

    # Assert button text is 'Log In'
    button_text = login_button_starts.text
    assert button_text == 'Log In', f"Expected button text 'Log In' but got '{button_text}'"

finally:
    driver.quit()

This script opens the login page and waits explicitly for the login button to appear using two XPath locators:

• contains(@class, 'login-btn') finds a button whose class attribute includes 'login-btn'.
• starts-with(@id, 'loginBtn') finds a button whose id attribute starts with 'loginBtn'.

We use WebDriverWait with visibility_of_element_located to wait until the button is visible, avoiding unreliable fixed waits.

Assertions check that the button is visible, enabled, and has the exact text 'Log In'.

Finally, the driver quits to close the browser.

Common Mistakes - 4 Pitfalls

Using hardcoded sleep instead of explicit waits

Using absolute XPath instead of relative XPath with contains/starts-with

Not verifying element visibility before interacting

{'mistake': 'Using incorrect XPath syntax for contains or starts-with', 'why_bad': 'Incorrect syntax causes locator failures and test errors.', 'correct_approach': "Use correct XPath functions: contains(@attribute, 'value') and starts-with(@attribute, 'value')."}

Bonus Challenge

Now add data-driven testing with 3 different login button class names and id prefixes to verify the button presence and text for each case.

Show Hint

Practice

1. Which XPath function would you use to find an element whose id attribute contains the text "submit" anywhere inside it?

easy

A. starts-with(@id, 'submit')

B. contains(@id, 'submit')

C. ends-with(@id, 'submit')

D. equals(@id, 'submit')

Solution

1. Step 1: Understand the contains() function

   The contains() function checks if an attribute or text includes a specific substring anywhere inside it.

2. Step 2: Apply contains() to the id attribute

   Using contains(@id, 'submit') finds elements where the id attribute has 'submit' anywhere in its value.

3. Final Answer:

   contains(@id, 'submit') -> Option B

4. Quick Check:

   contains() = substring anywhere [OK]

Hint: Use contains() to match substring anywhere in attribute [OK]

Common Mistakes:

• Using starts-with() when substring is not at start
• Using ends-with() which is not supported in XPath 1.0
• Using equals() which requires exact match

2. Which of the following is the correct XPath syntax to select elements whose class attribute starts with "btn-"?

easy

A. //element[@class^='btn-']

B. //element[contains(@class, 'btn-')]

C. //element[starts-with(@class, 'btn-')]

D. //element[@class*='btn-']

Solution

1. Step 1: Identify the correct function for 'starts with'

   The starts-with() function is used to check if an attribute value begins with a specific substring.

2. Step 2: Check XPath syntax

   The correct syntax is //element[starts-with(@class, 'btn-')]. Options C and D use invalid XPath syntax for this purpose.

3. Final Answer:

   //element[starts-with(@class, 'btn-')] -> Option C

4. Quick Check:

   starts-with() = prefix match [OK]

Hint: Use starts-with() for prefix matching in XPath [OK]

Common Mistakes:

• Using contains() instead of starts-with() for prefix
• Using CSS selector syntax like ^= or *= in XPath
• Missing parentheses in function call

3. What will be the result of this XPath query?

//div[contains(text(), 'Error') and starts-with(@class, 'alert-')]

Assuming the HTML contains:

<div class="alert-danger">Error: Invalid input</div>
<div class="alert-success">Success</div>
<div class="message-error">Error occurred</div>

medium

A. Selects only the div with class 'alert-danger'

B. Selects no elements

C. Selects all div elements containing 'Error'

D. Selects the first and second div elements

Solution

1. Step 1: Analyze contains(text(), 'Error')

   This matches div elements whose visible text includes 'Error'. The first and third divs contain 'Error'.

2. Step 2: Analyze starts-with(@class, 'alert-')

   This matches div elements whose class attribute starts with 'alert-'. The first and second divs match this.

3. Step 3: Combine both conditions with AND

   Only the first div satisfies both: text contains 'Error' and class starts with 'alert-'.

4. Final Answer:

   Selects only the div with class 'alert-danger' -> Option A

5. Quick Check:

   AND filters to first div only [OK]

Hint: AND requires both conditions true for selection [OK]

Common Mistakes:

• Assuming contains() matches attribute instead of text
• Ignoring the starts-with() condition
• Selecting all divs with 'Error' ignoring class prefix

4. You wrote this XPath to find buttons starting with "save":

//button[contains(@id, 'save-')]

But it also matches buttons with id "disable-save". How to fix it?

medium

A. //button[starts-with(@id, 'save-')]

B. //button[contains(text(), 'save-')]

C. //button[@id='save-']

D. //button[ends-with(@id, 'save-')]

Solution

1. Step 1: Understand why contains() matches unwanted ids

   contains(@id, 'save-') matches any id containing 'save-' anywhere, including 'disable-save'.

2. Step 2: Use starts-with() to match only ids beginning with 'save-'

   starts-with(@id, 'save-') ensures only ids starting exactly with 'save-' are matched.

3. Final Answer:

   //button[starts-with(@id, 'save-')] -> Option A

4. Quick Check:

   starts-with() fixes unwanted matches [OK]

Hint: Use starts-with() to avoid partial matches inside strings [OK]

Common Mistakes:

• Using contains() when prefix match is needed
• Using ends-with() which XPath 1.0 does not support
• Matching text() instead of attribute

5. You want to select all <a> elements where the href attribute starts with "https://" and the link text contains "Learn". Which XPath expression correctly does this?

hard

A. //a[contains(@href, 'https://') and contains(text(), 'Learn')]

B. //a[contains(text(), 'https://') and starts-with(@href, 'Learn')]

C. //a[starts-with(text(), 'Learn') and contains(@href, 'https://')]

D. //a[starts-with(@href, 'https://') and contains(text(), 'Learn')]

Solution

1. Step 1: Match href attribute starting with 'https://'

   Use starts-with(@href, 'https://') to ensure href begins exactly with 'https://'.

2. Step 2: Match link text containing 'Learn'

   Use contains(text(), 'Learn') to find links whose visible text includes 'Learn' anywhere.

3. Step 3: Combine both conditions with AND

   Both conditions must be true, so use and between them.

4. Final Answer:

   //a[starts-with(@href, 'https://') and contains(text(), 'Learn')] -> Option D

5. Quick Check:

   starts-with() + contains() combined correctly [OK]

Hint: Combine starts-with() for attribute and contains() for text [OK]

Common Mistakes:

• Using contains() for href prefix instead of starts-with()
• Swapping text() and attribute in functions
• Using starts-with() on text when contains() is needed