Some Major Test cases for web application cookie testing:

The first obvious test case is to test if your application is writing cookies properly on disk.
You can use the Cookie Tester application also if you don’t have any web application to test but you want to understand the cookie concept for testing.

Test cases:

1) As a Cookie privacy policy make sure from your design documents that no personal or sensitive data is stored in the cookie.

2) If you have no option than saving sensitive data in cookie make sure data stored in cookie is stored in encrypted format.

3) Make sure that there is no overuse of cookies on your site under test. Overuse of cookies will annoy users if browser is prompting for cookies more often and this could result in loss of site traffic and eventually loss of business.

4) Disable the cookies from your browser settings: If you are using cookies on your site, your sites major functionality will not work by disabling the cookies. Then try to access the web site under test. Navigate through the site. See if appropriate messages are displayed to user like “For smooth functioning of this site make sure that cookies are enabled on your browser”. There should not be any page crash due to disabling the cookies. (Please make sure that you close all browsers, delete all previously written cookies before performing this test)

5) Accepts/Reject some cookies: The best way to check web site functionality is, not to accept all cookies. If you are writing 10 cookies in your web application then randomly accept some cookies say accept 5 and reject 5 cookies. For executing this test case you can set browser options to prompt whenever cookie is being written to disk. On this prompt window you can either accept or reject cookie. Try to access major functionality of web site. See if pages are getting crashed or data is getting corrupted.

6) Delete cookie: Allow site to write the cookies and then close all browsers and manually delete all cookies for web site under test. Access the web pages and check the behavior of the pages.

7) Corrupt the cookies: Corrupting cookie is easy. You know where cookies are stored. Manually edit the cookie in notepad and change the parameters to some vague values. Like alter the cookie content, Name of the cookie or expiry date of the cookie and see the site functionality. In some cases corrupted cookies allow to read the data inside it for any other domain. This should not happen in case of your web site cookies. Note that the cookies written by one domain say rediff.com can’t be accessed by other domain say yahoo.com unless and until the cookies are corrupted and someone trying to hack the cookie data.

8) Checking the deletion of cookies from your web application page: Some times cookie written by domain say rediff.com may be deleted by same domain but by different page under that domain. This is the general case if you are testing some ‘action tracking’ web portal. Action tracking or purchase tracking pixel is placed on the action web page and when any action or purchase occurs by user the cookie written on disk get deleted to avoid multiple action logging from same cookie. Check if reaching to your action or purchase page deletes the cookie properly and no more invalid actions or purchase get logged from same user.

9) Cookie Testing on Multiple browsers: This is the important case to check if your web application page is writing the cookies properly on different browsers as intended and site works properly using these cookies. You can test your web application on Major used browsers like Internet explorer (Various versions), Mozilla Firefox, Netscape, Opera etc.

10) If your web application is using cookies to maintain the logging state of any user then log in to your web application using some username and password. In many cases you can see the logged in user ID parameter directly in browser address bar. Change this parameter to different value say if previous user ID is 100 then make it 101 and press enter. The proper access message should be displayed to user and user should not be able to see other users account.

To more information about What is Cookie? visit : Cookie