Interview Questions

Black Box testing for web-based application: (3)

Software Testing Methodolog

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Black Box testing for web-based application: (3)

16. Interface Testing
Many times, a web site is not an island. The site will call external servers for additional data, verification of data or fulfillment of orders.

16. Server interface
The first interface you should test is the interface between the browser and the server. You should attempt transactions, then view the server logs and verify that what you're seeing in the browser is actually happening on the server. It's also a good idea to run queries on the database to make sure the transaction data is being stored properly.

17. External interfaces
Some web systems have external interfaces. For example, a merchant might verify credit card transactions real-time in order to reduce fraud. You will need to send several test transactions using the web interface. Try credit cards that are valid, invalid, and stolen. If the merchant only takes Visa and MasterCard, try using a Discover card. (A script can check the first digit of the credit card number: 3 for American Express, 4 for Visa, 5 for MasterCard, or 6 for Discover, before the transaction is sent.) Basically, you want to make sure that the software can handle every possible message returned by the external server.

18. Error handling
One of the areas left untested most often is interface error handling. Usually we try to make sure our system can handle all of our errors, but we never plan for the other systems' errors or for the unexpected. Try leaving the site mid-transaction - what happens? Does the order complete anyway? Try losing the internet connection from the user to the server. Try losing the connection from the server to the credit card verification server. Is there proper error handling for all these situations? Are charges still made to credit cards? Is the interruption is not user initiated, does the order get stored so customer service reps can call back if the user doesn't come back to the site?

19. Compatibility
You will also want to verify that the application can work on the machines your customers will be using. If the product is going to the web for the world to use, you will need to try different combinations of operating system, browser, video setting and modem speed.

20. Operating systems
Does the site work for both MAC and IBM-Compatibles? Some fonts are not available on both systems, so make sure that secondary fonts are selected. Make sure that the site doesn't use plug-ins only available for one OS, if your users will use both.

21. Browsers
Does your site work with Netscape? Internet Explorer? Lynx? Some HTML commands or scripts only work for certain browsers. Make sure there are alternate tags for images, in case someone is using a text browser. If you're using SSL security, you only need to check browsers 3.0 and higher, but verify that there is a message for those using older browsers.

22. Video settings
Does the layout still look good on 640x400 or 600x800? Are fonts too small to read? Are they too big? Does all the text and graphic alignment still work?

23. Modem/connection speeds
Does it take 10 minutes to load a page with a 28.8 modem, but you tested hooked up to a T1? Users will expect long download times when they are grabbing documents or demos, but not on the front page. Make sure that the images aren't too large. Make sure that marketing didn't put 50k of font size -6 keywords for search engines.

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