Difference between client-server testing and web based testing and what are things that we need to test in such applications?

Projects are broadly divided into two types of:

• 2 tier applications
• 3 tier applications

CLIENT / SERVER TESTING
This type of testing usually done for 2 tier applications (usually developed for LAN)
Here we will be having front-end and backend.

The application launched on front-end will be having forms and reports which will be monitoring and manipulating data

E.g: applications developed in VB, VC++, Core Java, C, C++, D2K, PowerBuilder etc.,
The backend for these applications would be MS Access, SQL Server, Oracle, Sybase, Mysql, Quadbase

The tests performed on these types of applications would be
- User interface testing
- Manual support testing
- Functionality testing
- Compatibility testing & configuration testing
- Intersystem testing

WEB TESTING
This is done for 3 tier applications (developed for Internet / intranet / xtranet)
Here we will be having Browser, web server and DB server.

The applications accessible in browser would be developed in HTML, DHTML, XML, JavaScript etc. (We can monitor through these applications)

Applications for the web server would be developed in Java, ASP, JSP, VBScript, JavaScript, Perl, Cold Fusion, PHP etc. (All the manipulations are done on the web server with the help of these programs developed)

The DBserver would be having oracle, sql server, sybase, mysql etc. (All data is stored in the database available on the DB server)

The tests performed on these types of applications would be
- User interface testing
- Functionality testing
- Security testing
- Browser compatibility testing
- Load / stress testing
- Interoperability testing/intersystem testing
- Storage and data volume testing

A web-application is a three-tier application.
This has a browser (monitors data) [monitoring is done using html, dhtml, xml, javascript]-> webserver (manipulates data) [manipulations are done using programming languages or scripts like adv java, asp, jsp, vbscript, javascript, perl, coldfusion, php] -> database server (stores data) [data storage and retrieval is done using databases like oracle, sql server, sybase, mysql].

The types of tests, which can be applied on this type of applications, are:
1. User interface testing for validation & user friendliness
2. Functionality testing to validate behaviors, i/p, error handling, o/p, manipulations, services levels, order of functionality, links, content of web page & backend coverage’s
3. Security testing
4. Browser compatibility
5. Load / stress testing
6. Interoperability testing
7. Storage & data volume testing

A client-server application is a two tier application.
This has forms & reporting at front-end (monitoring & manipulations are done) [using vb, vc++, core java, c, c++, d2k, power builder etc.,] -> database server at the backend [data storage & retrieval) [using ms access, sql server, oracle, sybase, mysql, quadbase etc.,]

The tests performed on these applications would be
1. User interface testing
2. Manual support testing
3. Functionality testing
4. Compatibility testing
5. Intersystem testing
Some more points to clear the difference between client server, web and desktop applications:

Desktop application:
1. Application runs in single memory (Front end and Back end in one place)
2. Single user only

Client/Server application:
1. Application runs in two or more machines
2. Application is a menu-driven
3. Connected mode (connection exists always until logout)
4. Limited number of users
5. Less number of network issues when compared to web app.

Web application:
1. Application runs in two or more machines
2. URL-driven
3. Disconnected mode (state less)
4. Unlimited number of users
5. Many issues like hardware compatibility, browser compatibility, version compatibility, security issues, performance issues etc.

As per difference in both the applications come where, how to access the resources. In client server once connection is made it will be in state on connected, whereas in case of web testing http protocol is stateless, then there comes logic of cookies, which is not in client server.

For client server application users are well known, whereas for web application any user can login and access the content, he/she will use it as per his intentions.

So, there are always issues of security and compatibility for web application.

Website Cookie Testing

We will first focus on what exactly cookies are and how they work. It would be easy for you to understand the test cases for testing cookies when you have clear understanding of how cookies work? How cookies stored on hard drive? And how can we edit cookie settings?
What is Cookie?
Cookie is small information stored in text file on user’s hard drive by web server. This information is later used by web browser to retrieve information from that machine. Generally cookie contains personalized user data or information that is used to communicate between different web pages.
Why Cookies are used?
Cookies are nothing but the user’s identity and used to track where the user navigated throughout the web site pages. The communication between web browser and web server is stateless.
For example if you are accessing domain http://www.example.com/1.html  then web browser will simply query to example.com web server for the page 1.html. Next time if you type page as http://www.example.com/2.html  then new request is send to example.com web server for sending 2.html  page and web server don’t know anything about to whom the previous page 1.html served.
What if you want the previous history of this user communication with the web server? You need to maintain the user state and interaction between web browser and web server somewhere. This is where cookie comes into picture. Cookies serve the purpose of maintaining the user interactions with web server.
How cookies work?
The HTTP protocol used to exchange information files on the web is used to maintain the cookies. There are two types of HTTP protocol. Stateless HTTP and Stateful HTTP protocol. Stateless HTTP protocol does not keep any record of previously accessed web page history. While Stateful HTTP protocol do keep some history of previous web browser and web server interactions and this protocol is used by cookies to maintain the user interactions.
Whenever user visits the site or page that is using cookie, small code inside that HTML page (Generally a call to some language script to write the cookie like cookies in JAVAScript, PHP, Perl) writes a text file on users machine called cookie.
Here is one example of the code that is used to write cookie and can be placed inside any HTML page:
Set-Cookie: NAME=VALUE; expires=DATE; path=PATH; domain=DOMAIN_NAME;
When user visits the same page or domain later time this cookie is read from disk and used to identify the second visit of the same user on that domain. Expiration time is set while writing the cookie. This time is decided by the application that is going to use the cookie.
Generally two types of cookies are written on user machine.
1) Session cookies: This cookie is active till the browser that invoked the cookie is open. When we close the browser this session cookie gets deleted. Sometime session of say 20 minutes can be set to expire the cookie.
2) Persistent cookies: The cookies that are written permanently on user machine and last for months or years.
Where cookies are stored?
When any web page application writes cookie it get saved in a text file on user hard disk drive. The path where the cookies get stored depends on the browser. Different browsers store cookie in different paths. E.g. Internet explorer store cookies on path “C:\Documents and Settings\Default User\Cookies”
Here the “Default User” can be replaced by the current user you logged in as. Like “Administrator”, or user name like “Vijay” etc.
The cookie path can be easily found by navigating through the browser options. In Mozilla Firefox browser you can even see the cookies in browser options itself. Open the Mozilla browser, click on Tools->Options->Privacy and then “Show cookies” button.
How cookies are stored?
Let’s take example of cookie written by rediff.com on Mozilla Firefox browser:
On Mozilla Firefox browser when you open the page rediff.com or login to your rediffmail account, a cookie will get written on your Hard disk. To view this cookie simply click on “Show cookies” button mentioned on above path. Click on Rediff.com site under this cookie list. You can see different cookies written by rediff domain with different names.
Site: Rediff.com Cookie name: RMID
Name: RMID (Name of the cookie)
Content: 1d11c8ec44bf49e0… (Encrypted content)
Domain: .rediff.com
Path: / (Any path after the domain name)
Send For: Any type of connection
Expires: Thursday, December 31, 2020 11:59:59 PM
Applications where cookies can be used:
1) To implement shopping cart:
Cookies are used for maintaining online ordering system. Cookies remember what user wants to buy. What if user adds some products in their shopping cart and if due to some reason user don’t want to buy those products this time and closes the browser window? When next time same user visits the purchase page he can see all the products he added in shopping cart in his last visit.
2) Personalized sites:
When user visits certain pages they are asked which pages they don’t want to visit or display. User options are get stored in cookie and till the user is online, those pages are not shown to him
3) User tracking:
To track number of unique visitors online at particular time.
4) Marketing:
Some companies use cookies to display advertisements on user machines. Cookies control these advertisements. When and which advertisement should be shown? What is the interest of the user? Which keywords he searches on the site? All these things can be maintained using cookies.
5) User sessions:
Cookies can track user sessions to particular domain using user ID and password.
Drawbacks of cookies:
1) Even writing Cookie is a great way to maintain user interaction, if user has set browser options to warn before writing any cookie or disabled the cookies completely then site containing cookie will be completely disabled and cannot perform any operation resulting in loss of site traffic.
2) Too many Cookies:
If you are writing too many cookies on every page navigation and if user has turned on option to warn before writing cookie, this could turn away user from your site.
3) Security issues:
Sometimes users personal information is stored in cookies and if someone hack the cookie then hacker can get access to your personal information. Even corrupted cookies can be read by different domains and lead to security issues.
4) Sensitive information:
Some sites may write and store your sensitive information in cookies, which should not be allowed due to privacy concerns.
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 behaviour 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: Sometimes 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 says 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.

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