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Posts Tagged ‘regression testing’

You just finished building your company’s website. You have tested it yourself and had other company employees test it. The website now goes live. A few weeks later you start getting emails from irate customers who complain that they are unable to place their orders because certain steps in the “Buy Now” process give errors. You quickly fix the problem. A few days later you get complaints about some other issue and you again react quickly to fix the website. This continues for a few months till the complaints finally halt and things stabilize. At this point you make some enhancements to your website. A few days later a customer email alerts you to the fact that in the process of making this enhancement you “broke” something else on the website. Again you spend time to find and fix the problem but by now you are perplexed and not a little frustrated. These issues have cost you many customers in the last few months and potentially spread ill will across the broader customer community. It seems to you that the only way to have detected these issues before they went “live” was to have employed a large army of software testers, something your company is unable to afford. Enter automated software testing. While nothing can replace good human testers, broad test coverage requires some degree of software automation for it to be economically feasible. Automated testing tools can provide a huge workforce multiplier and do a very good job complimenting human testers. Every change to your website no matter how small requires thorough testing to ensure that nothing else was affected. This becomes very time consuming very quickly due to the large number of possible cases to test. A strategy whereby tests are automated using software becomes an economic necessity. There are two classes of automated testing tools. The first kind, functional and regression testing tools, helps to make sure that the website behaves as it should: for example if a customer clicks on button X, page Y is displayed without errors. Functional and regression testing tools are able to automate a large number of scenarios to ensure that your website works as intended. The second type, load testing tools gauge how well your website performs when subjected to a large stress, such as a large number of simultaneous users. I will be discussing load testing in a separate article. I will now give you an overview of the basic characteristics of functional testing. Before you can begin any kind of functional test automation you will need to identify the test scenarios you wish to automate. Once this is done, you will need to generate test scripts that cover these scenarios. A functional testing tool will typically record user interactions with a website. As you perform various operations on your website or application, the tool records every step. When you finish recording, it generates an automated script from your interactions with your website. Alternatively you could use the tool to construct the script by hand. Typically testers tend to do a combination of the two. They will use the recorder to generate the basic framework of their scripts and then tweak the scripts by hand to incorporate special cases. Scripts can be graphical and/or text based in nature. A good functional testing tool does not require users to have a programming background. Users not proficient in programming will work predominantly with graphical scripts. In most tools graphical scripts will typically show all interactions in a tree structure and users can edit any node of the tree to modify the script. Some users however, who have programming backgrounds may wish to program their scripts. These users will typically work with a text script written in a standard language such as JavaScript or VBScript. Once you have generated your script you will need to insert checks in your scripts to test if your website is functioning correctly. Such checks are usually called checkpoints. A checkpoint verifies that values of a property obtained when testing the website match expected values. Checkpoints enable you to set the criteria for comparing expected values with obtained values. The expected value of a property is derived from recording interactions with the web site. It is viewed and modified from checkpoints. The current value is retrieved during replay (i.e. during the execution of the test case). There are many different kinds of checkpoints. A page checkpoint verifies the source of a page or frame as well as its statistical properties. You can check for broken links, verify link URLs, image sources, the hierarchy of HTML tags or even the entire HTML source of the Web page or frame. You can also set thresholds for the loading time of a page. A text checkpoint verifies that a given text is displayed or is not displayed in a specified area on a web page. A web object checkpoint verifies the properties of a web object e.g. the value of an HTML INPUT field. A database checkpoint verifies the contents of a database used by your website. When you replay a test script, the testing tool will open the recorded application and perform the recorded steps in the same sequence they were specified in the script. As it replays the script it will also run through all the checkpoints you have inserted into the script. In addition, you can test your application’s behavior with varying data inputs. For example you can try to submit a page after entering different values in the edit box of a web page. At the end of the replay a detailed report is typically be generated. Functional test automation allows you to automate the repetitive testing of a large number of scenarios across your website. Functional testing tools are an important weapon in your development arsenal whose use provides a huge productivity gain and allows for small testing groups to accomplish significantly more work. There is a very strong economic case for the use of Functional Testing Tools as part of the development and deployment cycle of a website.

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Many organizations are interested in building web applications for their business but are unaware of the various steps that are needed to build a compelling web application. In this article I will attempt to put together the various pieces of the puzzle. Application development involves several distinct efforts that need to come together to build a compelling end product. A compelling end product is the combination of design, development architecture, development implementation, automated regression and functional testing and performance and load testing. Design: People often confuse design with development. Moreover even within design, user interface design is often confused with graphics design. Web user interface design involves the design of the flow of the website and the layout of the specific web pages within the website. The web user interface designer concentrates on the usability of the application. The user interface designer will typically develop “wireframes” using tools like Adobe Photoshop to convey the design. These are often initially developed as prototypes and usability testing is carried with user groups out to ensure that the web application will be intuitive and easy to use. Graphics design on the other hand relates to the aesthetics of the page. The graphics designer is responsible for the aesthetic layout of the pages and the creation of the various graphical objects inside the pages such as images and flash objects. The graphics Designer will typically use a combination of tools such as Adobe Photoshop, Adobe Illustrator and Adobe Captivate to create the actual graphics objects. A designer will need to work closely with other groups to make sure the design process does not compromise the performance of the application by making sure that the graphics objects are small thus ensuring that the various web performance metrics are unaffected. Development: This involves converting the design into an actual application. The development typically involves an architectural phase where the underlying modules that make up the application are scoped out. If persistent data storage is needed, a database schema should be designed to accommodate the data storage needs. The choice of the operating system (e.g. Windows, Linux or Solaris) where the web application will run, the web server (e.g. Microsoft IIS, Apache or Tomcat) which will run the web application and the back end database (e.g. Microsoft SQL Server, Oracle, MySQL or Postgres) which stores the data will need to be made. Various development frameworks are available to build web applications. The most common ones are ASP and ASP.NET from Microsoft, Java Servlets and JSP from Sun, PHP and Perl that are open source. The choice of the application framework is typically dictated by the strengths of the members of the development team. The architectural phase is followed by the implementation phase. This is typically the longest part of the project and during this phase the actual code is written using the design specifications and graphics objects developed by the design team. The programming will typically be done using a combination of the application frameworks mentioned earlier together with HTML, JavaScript and CSS style sheets. Quality Assurance and Testing: A surprising number of people are of the view that quality assurance and testing is desirable but is not actually needed. Unfortunately this view has its roots in total ignorance of the process that is needed to build a good end product. Regardless of how pretty or slick we make the application, if it does not work as expected, users will reject it. Quality assurance and testing involve two different kinds of tasks. Functional and regression testing is used to verify that the developed application is doing what it is supposed to do. This is achieved by test automation using a functional testing tool. Load and Performance testing is used to ensure that the application performs as intended when it is subjected to the typical load of a production environment. Load testing is practically speaking impossible to perform without using an automated load testing tool since it involves the simulation of a large number of concurrent virtual users. This effect cannot really be achieved manually and needs the assistance of an application that is designed to subject the application to a specified load and then measure its performance when it is subjected to that load. Quality Assurance teams will need to track the bugs or defects in the application using bug tracking tools. Such tools will allow defects to be tracked by all members of the team. The three groups mentioned above tend to be specialized for their skill set. As an example, people often make the mistake of using developers as quality assurance testers. This is not a wise strategy because most developers who are good at writing software are quite poor at finding bugs or defects in their own software. Writing good and compelling web applications requires an understanding of all phases of the process, design, development and quality assurance. Skipping phases or taking shortcuts will result in low quality software that will generally cost more in the long run.

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