Test newsletter subscription block ->For new subscriber ->For existing subscriber
User signup (account creation.)
User password change/recovery -> For new user -> For existing user
Test Magento multi-store fronts (if exists.)
Check theme & its components on the website are working (looking) fine.
Click through all category pages and check for; -> Layered navigation showing and working correctly -> Sorting/Filters working correctly
Open at least 5-10 product pages and check for; -> Correct price -> Add to cart button -> Configurable options, if applicable -> Images
Check working of search and Advance search
Add item to cart
Add multiple items to cart
Test Remove item button
Test Update shopping cart button
Test Clear shopping cart button
Check correct price
Check correct totals (discount/tax/etc)
Check if login works
Place some orders; -> Multiple products -> With discounts -> Let the transaction fail to see how Magento handles canceled orders -> Try all combinations of payment methods & shipping methods -> Try guest checkouts as well as logged-in checkouts
All shipping methods available?
All payment methods available?
Login & logout
Are the correct My Accounts options showing?
Reorder an order
Subscribe / unsubscribe for newsletter
Place an order through the backend
Create a customer through the backend
Open all pages to see whether exceptions occur
Check all configuration options for all extensions in the backend