Monday, August 4, 2008

Software Testing - Boundary-value analysis

Boundary-value analysis is a variant and refinement of equivalence partitioning, with two major differences: First, rather than selecting any element in an equivalence class as being representative, elements are selected such that each edge of the EC is the subject of a test. Boundaries are always a good place to look for defects. Second, rather than focusing exclusively on input conditions, output conditions are also explored by defining output ECs. What can be output? What are the classes of output? What should I create as an input to force a useful set of classes that represent the outputs that ought to be produced? The guidelines for boundary-value analysis are: · If an input specifies a range of valid values, write test cases for the ends of the range and invalid-input test cases for conditions just beyond the ends. Example: If the input requires a real number in the range 0.0 to 90.0 degrees, then write test cases for 0.0, 90.0, -0.001, and 90.001. · If an input specifies a number of valid values, write test cases for the minimum and maximum number of values and one beneath and beyond these values. Example: If the input requires the titles of at least 3, but no more than 8, books, then write test cases for 2, 3, 8, and 9 books. · Use the above guidelines for each output condition. Boundary-value analysis is not as simple as it sounds, because boundary conditions may be subtle and difficult to identify. The method does not test combinations of input conditions.

What is Cookie testing & Security 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? Explain Cookies? 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. Some time 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 lasts 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 Mozila browser, click on Tools->Options->Privacy and then “Show cookies” button. How cookies are stored? Lets 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.comPath: / (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 can not 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:Some times 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 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. These are some Major test cases to be considered while testing website cookies. You can write multiple test cases from these test cases by performing various combinations. If you have some different application scenario, you can mention your test cases in comments below.

What is Client server testing & Web testing?

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 testingSome 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 users5. 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.

Software Testing - Error Guessing

Error guessing is an ad hoc approach, based on intuition and experience, to identify tests that are considered likely to expose errors. The basic idea is to make a list of possible errors or error-prone situations and then develop tests based on the list. What are the most common error-prone situations we have seen before? Defects’ histories are useful. There is a high probability that defects that have been there in the past are the kind that are going to be there in the future. Some items to try are: · empty or null lists/strings · zero instances/occurrences · blanks or null characters in strings · negative numbers One of the studies done by Myers (1979) states that the probability of errors remaining in the program is proportional to the number of errors that have been found so far. This alone provides a rich source of focus for productive error guessing.

What is Load and Performance testing

Load Testing and Performance Testing are commonly said as positive testing where as Stress Testing is said to be as negative testing. Say for example there is a application which can handle 25 simultaneous user logins at a time. In load testing we will test the application for 25 users and check how application is working in this stage, in performance testing we will concentrate on the time taken to perform the operation. Where as in stress testing we will test with more users than 25 and the test will continue to any number and we will check where the application is cracking the Hardware resources.

Software Testing - Graph Matrix

A graph matrix is a square matrix whose size is equivalent to the number of nodes in the flow graph. Each row and column correspond to a particular node and the matrix corresponds to the connections (edges) between nodes. By adding a link weight to each matrix entry, more information about the control flow can be captured. In its simplest form, the link weight is 1 if an edge exists and 0 if it does not. But other types of link weights can be represented:1. the probability that an edge will be executed,2. the processing time expended during link traversal,3. the memory required during link traversal, or 4. the resources required during link traversal.Graph theory algorithms can be applied to these graph matrices to help in the analysis necessary to produce the basis set.

Manual Testing - Cause Effect Graph

A cause-effect graph is a directed graph that maps a set of causes to a set of effects. The causes may be thought of as the input to the program, and the effects may be thought of as the output. Usually the graph shows the nodes representing the causes on the left side and the nodes representing the effects on the right side. There may be intermediate nodes in between that combine inputs using logical operators such as AND and OR.
Constraints may be added to the causes and effects. These are represented as edges labelled with the constraint symbol using a dashed line. For causes, valid constraint symbols are E (exclusive?), O (one and only one?), and I (at least one?). For effects, valid constraint symbols are R (Require?) and M (Mask?). (This information needs to be verified.)

The graph's direction is as follows:
(XXX: a figure would represent this better)Causes --> intermediate nodes --> Effects It is a proven technique for effective requirements validation and test case design, cause-effect graphing is the process of transforming specifications into a graphic representation. This graphic representation depicts the functional relationships and conditions present in the requirements, illustrating how each input relates to every other input, as well as every output.

Constraints and observability of nodes also are established during this process, allowing the project team to identify potential problem areas. In developing the cause-effect graph, the test team evaluates the requirements for completeness, consistency, sufficient level of detail and lack of ambiguity, often finding defects that otherwise would not be found until integration testing.