While testing a web application you need to consider following Cases

• Functionality Testing
• Performance Testing
• Usability Testing
• Server Side Interface
• Client Side Compatibility
• Security
Functionality:
In testing the functionality of the web sites the following should be tested:
• Links
i. Internal Links
ii. External Links
iii. Mail Links
iv. Broken Links
• Forms
i. Field validation
ii. Error message for wrong input
iii. Optional and Mandatory fields

Test  Forms are working as expected. This will include-

• Scripting checks on the form are working as expected. For example- if a user does not fill a mandatory field in a form a error message is shown.
• Check default values are being populated
• Once submitted , the data in the forms is submitted to a live database or is linked to an working email address
• Forms are optimally formatted for better readability

• Database
* Testing will be done on the database integrity.
• Cookies
* Testing will be done on the client system side, on the temporary Internet files.
Test Cookies are working as expected. Cookies are small files used by websites to primarily remember active user sessions so you do not to log in every time you visit a website. Cookie Testing will include

• Testing cookies (sessions) are deleted either when cache is cleared or when they reach their expiry.
• Delete cookies (sessions) and test that login credentials are asked for when you next visit the site.

Performance :
Performance testing can be applied to understand the web site’s scalability, or to benchmark the performance in the environment of third party products such as servers and middleware for potential purchase.
• Connection Speed:
Tested over various networks like Dial Up, ISDN etc
• Load:
i. What is the no. of users per time?
ii. Check for peak loads and how system behaves
iii. Large amount of data accessed by user
• Stress:
i. Continuous Load
ii. Performance of memory, CPU, file handling etc..
Usability:
Usability testing is the process by which the human-computer interaction characteristics of a system are measured, and weaknesses are identified for correction.
• Ease of learning
• Navigation
• Subjective user satisfaction
• General appearance
Server Side Interface:
In web testing the server side interface should be tested. This is done by verify that communication is done properly. Compatibility of server with software, hardware, network and database should be tested.
Client Side Compatibility:
The client side compatibility is also tested in various platforms, using various browsers etc.
Security:
The primary reason for testing the security of a web is to identify potential vulnerabilities and subsequently repair them.
• Network Scanning
• Vulnerability Scanning
• Password Cracking
• Log Review
• Integrity Checkers
• Virus Detection

Details on web application testing with web testing test cases

Let’s have first web testing checklist.
1) Functionality Testing
2) Usability testing
3) Interface testing
4) Compatibility testing
5) Performance testing
6) Security testing
1) Functionality Testing:
Test for – all the links in web pages, database connection, forms used in the web pages for submitting or getting information from user, Cookie testing.
Check all the links:

• Test the outgoing links from all the pages from specific domain under test.
• Test all internal links.
• Test links jumping on the same pages.
• Test links used to send the email to admin or other users from web pages.
• Test to check if there are any orphan pages.
• Lastly in link checking, check for broken links in all above-mentioned links.

Test forms in all pages:
Forms are the integral part of any web site. Forms are used to get information from users and to keep interaction with them. So what should be checked on these forms?

• First check all the validations on each field.
• Check for the default values of fields.
• Wrong inputs to the fields in the forms.
• Options to create forms if any, form delete, view or modify the forms.

Let’s take example of the search engine project currently I am working on, In this project we have advertiser and affiliate signup steps. Each sign up step is different but dependent on other steps. So sign up flow should get executed correctly. There are different field validations like email Ids, User financial info validations. All these validations should get checked in manual or automated web testing.
Cookies testing:
Cookies are small files stored on user machine. These are basically used to maintain the session mainly login sessions. Test the application by enabling or disabling the cookies in your browser options. Test if the cookies are encrypted before writing to user machine. If you are testing the session cookies (i.e. cookies expire after the session’s ends) check for login sessions and user stats after session end. Check effect on application security by deleting the cookies.
Validate your HTML/CSS:
If you are optimizing your site for Search engines then HTML/CSS validation is very important. Mainly validate the site for HTML syntax errors. Check if site is crawlable to different search engines.
Database testing:
Data consistency is very important in web application. Check for data integrity and errors while you edit, delete, modify the forms or do any DB related functionality.
Check if all the database queries are executing correctly, data is retrieved correctly and also updated correctly. More on database testing could be load on DB, we will address this in web load or performance testing below.
2) Usability Testing:
Test for navigation:
Navigation means how the user surfs the web pages, different controls like buttons, boxes or how user using the links on the pages to surf different pages.
Usability testing includes:
Web site should be easy to use. Instructions should be provided clearly. Check if the provided instructions are correct means whether they satisfy purpose.
Main menu should be provided on each page. It should be consistent.
Content checking:
Content should be logical and easy to understand. Check for spelling errors. Use of dark colors annoys users and should not be used in site theme. You can follow some standards that are used for web page and content building. These are common accepted standards like as I mentioned above about annoying colors, fonts, frames etc.
Content should be meaningful. All the anchor text links should be working properly. Images should be placed properly with proper sizes.
These are some basic standards that should be followed in web development. Your task is to validate all for UI testing
Other user information for user help:
Like search option, sitemap, help files etc. Sitemap should be present with all the links in web sites with proper tree view of navigation. Check for all links on the sitemap.
“Search in the site” option will help users to find content pages they are looking for easily and quickly. These are all optional items and if present should be validated.
3) Interface Testing:
Three areas to be tested here are - Application , Web and Database Server

• Application: Test  requests are sent correctly to the Database and output at the client side is displayed correctly. Errors if any must be caught by the application and must be only shown to the administrator and not the end user.
• Web Server: Test  Web server is handling all application requests without any service denial.
• Database Server: Make sure queries sent to the database give expected results.

Check if all the interactions between these servers are executed properly. Errors are handled properly. If database or web server returns any error message for any query by application server then application server should catch and display these error messages appropriately to users. Check what happens if user interrupts any transaction in-between? Check what happens if connection to web server is reset in between?
4) Compatibility Testing:
Compatibility of your web site is very important testing aspect. See which compatibility test to be executed:

• Browser compatibility
• Operating system compatibility
• Mobile browsing
• Printing options

Browser compatibility:
In my web-testing career I have experienced this as most influencing part on web site testing.
Some applications are very dependent on browsers. Different browsers have different configurations and settings that your web page should be compatible with. Your web site coding should be cross browser platform compatible. If you are using java scripts or AJAX calls for UI functionality, performing security checks or validations then give more stress on browser compatibility testing of your web application.
Test web application on different browsers like Internet explorer, Firefox, Netscape navigator, AOL, Safari, Opera browsers with different versions.
OS compatibility:
Some functionality in your web application is may not be compatible with all operating systems. All new technologies used in web development like graphics designs, interface calls like different API’s may not be available in all Operating Systems.
Test your web application on different operating systems like Windows, Unix, MAC, Linux, Solaris with different OS flavors.
Mobile browsing:
This is new technology age. So in future Mobile browsing will rock. Test your web pages on mobile browsers. Compatibility issues may be there on mobile.
Printing options:
If you are giving page-printing options then make sure fonts, page alignment, page graphics getting printed properly. Pages should be fit to paper size or as per the size mentioned in printing option.
5) Performance testing:
Web application should sustain to heavy load. Web performance testing should include:
Web Load Testing
Web Stress Testing
Test application performance on different internet connection speed.
In web load testing test if many users are accessing or requesting the same page. Can system sustain in peak load times? Site should handle many simultaneous user requests, large input data from users, Simultaneous connection to DB, heavy load on specific pages etc.
Stress testing: Generally stress means stretching the system beyond its specification limits. Web stress testing is performed to break the site by giving stress and checked how system reacts to stress and how system recovers from crashes.
Stress is generally given on input fields, login and sign up areas.
In web performance testing web site functionality on different operating systems, different hardware platforms is checked for software, hardware memory leakage errors,
This will ensure your site works under all loads. Testing activities will include but not limited to -

• Website application response times at different connection speeds
• Load test your web  application to determine its behavior under normal and peak loads
• Stress test your web site to determine its break point when pushed to beyond normal loads at peak time.
• Test if a crash occurs due to peak load , how does the site recover from such an event
• Make sure optimization techniques like gzip compression , browser and server side cache enabled to reduce load times

6) Security Testing:
Following are some test cases for web security testing:

• Test by pasting internal url directly into browser address bar without login. Internal pages should not open.
• If you are logged in using username and password and browsing internal pages then try changing url options directly. I.e. If you are checking some publisher site statistics with publisher site ID= 123. Try directly changing the url site ID parameter to different site ID which is not related to logged in user. Access should denied for this user to view others stats.
• Try some invalid inputs in input fields like login username, password, input text boxes. Check the system reaction on all invalid inputs.
• Web directories or files should not be accessible directly unless given download option.
• Test the CAPTCHA for automates scripts logins.
• Test if SSL is used for security measures. If used proper message should get displayed when user switch from non-secure http:// pages to secure https:// pages and vice versa.
• All transactions, error messages, security breach attempts should get logged in log files somewhere on web server.
• Restricted files should not be downloadable without appropriate access
• Check sessions are automatically killed after prolonged user inactivity

Points to be considered while testing a Web site

Web sites are essentially client/server applications -
with web servers and ‘browser’ clients.
Consideration should be given to the interactions between html pages, TCP/IP communications, Internet connections, firewalls, applications that run in web pages (such as applets, JavaScript, plug-in applications), and applications that run on the server side (such as CGI scripts, database interfaces, logging applications, dynamic page generators, asp, etc.).
Additionally, there are a wide variety of servers and browsers, various versions of each, small but sometimes significant differences between them, variations in connection speeds, rapidly changing technologies, and multiple standards and protocols. The end result is that testing for web sites can become a major on-going effort.
Other considerations might include:
   

1.      What are the expected loads on the server (e.g., number of hits per unit time?), and what kind of performance is required under such loads (such as web server response time, database query response times). What kinds of tools will be needed for performance testing (such as web load testing tools, other tools already in house that can be adapted, web robot downloading tools, etc.)?

2.      Who is the target audience? What kind of browsers will they be using? What kinds of connection speeds will they be using? Are they intra- organization (thus with likely high connection speeds and similar browsers) or Internet-wide (thus with a wide variety of connection speeds and browser types)?

3.      What kind of performance is expected on the client side (e.g., how fast should page appear, how fast should animations, applets, etc. load and run)?

4.      Will down time for server and content maintenance/upgrades be allowed? How much?

5.      What kinds of security (firewalls, encryptions, passwords, etc.) will be required and what is it expected to do? How can it be tested?

6.      How reliable are the site’s Internet connections required to be? And how does that affect backup system or redundant connection requirements and testing?

7.      What processes will be required to manage updates to the web site’s content, and

8.      What are the requirements for maintaining, tracking, and controlling page content, graphics, links, etc.?

9.      Which HTML specification will be adhered to? How strictly? What variations will be allowed for targeted browsers?

10.  Will there be any standards or requirements for page appearance and/or graphics throughout a site or parts of a site??

11.  How will internal and external links be validated and updated? how often?
Can testing be done on the production system, or will a separate test system be required? How are browser caching, variations in browser option settings, dial-up connection variabilities, and real-world internet ‘traffic congestion’ problems to be accounted for in testing?

12.  How extensive or customized are the server logging and reporting requirements; are they considered an integral part of the system and do they require testing?

13.  How are cgi programs, applets, javascripts, ActiveX components, etc. to be maintained, tracked, controlled, and tested?
Pages should be 3-5 screens max unless content is tightly focused on a single topic. If larger, provide internal links within the page.

14.  The page layouts and design elements should be consistent throughout a site, so that it’s clear to the user that they’re still within a site.

15.  Pages should be as browser-independent as possible, or pages should be provided or generated based on the browser-type.

16.  All pages should have links external to the page; there should be no dead-end pages.
The page owner, revision date, and a link to a contact person or organization should be included on each page.