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Automated Testing
Every software development group tests its products but still defects are always present in delivered software. Test engineerings always try to catch these errors but they always creep in and they often reappear, even with the best manual testing processes. Automated software testing is the best way to increase the effectiveness, efficiency and coverage of software testing. Automation Testing is the use of software to control the execution of tests, the comparison of actual outcomes to predicted outcomes, the setting up of test preconditions, test design, and other test control and test reporting functions. usually, test automation involves automating a manual process already in existence that uses a formalized testing process. There are many tools available to perform automation testing today.
Manual Testing
Manual testing is the method in which testing of the software is done manually. In this type of testing, a tester acts like an end-user. All features of a software are tested to know if the behavior of the software is exactly according to the expectations of the customer. The tester uses a test plan. Other than test plan, there are test cases written, which are used for implementing the test plan. Although manual tests may find many defects in a software application, it is a laborious and time consuming process. In addition, it may not be effective in finding certain classes of defects.
Why Automation Testing
Automated software testing has long been considered critical for big software development organizations but is often thought to be too expensive or difficult for smaller companies to implement. Many companies are recognizing the importance of automating the work of testers and including the auto-test as part of the regular build process. The results of the automatic test are seen as a measure of the current quality of the software. Combined with a code coverage tool it gives the answer to the all-elusive question: "How much of my code is currently running ok?."
The below factors make automation testing important:
Automated Testing is both Time and Money Saving
During software development cycle, software tests have to be repeated very often to ensure quality. Software tests need to be repeated, every time a change in the source code happens. For each release of the software it may be tested on all supported operating systems and hardware configurations. Repeating these tests manually is costly and time consuming. Once created, automated tests can be run over and over again at no additional cost and they are much faster than manual tests. The time to run these repetitive tests is reduced from days to hours by automated software testing. Saving the time directly translates into cost savings.
Improves Accuracy
Manual testers are bound to make mistakes during monotonous manual testing. With Automated tests, the probability of errors occuring is relatively low. Automated tests perform the same steps precisely every time they are executed and never forget to record detailed results.
Increases Test Coverage
Automated software testing can increase the depth and scope of tests to help improve software quality. Lengthy tests that are difficult to be conducted manually can be run unattended in Automation testing. They can even be run on multiple computers with different configurations. Automated software tests can easily execute thousands of different complex test cases during every test run providing test coverage that is impossible with manual tests.
Automated Software Testing Does What Manual Testing Cannot
A controlled web application test with thousands of users cannot be performed by even the largest software departments. Automated testing can simulate tens, hundreds or thousands of virtual users interacting with network or web software and applications.
Helps Developers and Testers
Shared automated tests can be used by developers to find problems quickly before sending the code for Quality assurance. Tests would run automatically whenever source code changes are checked in and in case of failure error reports would be automatically sent to the team or the developer. Features like these save developers time and increase their confidence.
Improves Team Morale
Automating repetitive tasks with automated software testing gives the project team , time to spend on more challenging and rewarding projects. Team members improve their skill sets and confidence and, in turn, pass those gains on to their organization.
Approaches to Test Automation
Code-driven testing
Code driven test automation is a key feature of agile software development, where it is known as test-driven development (TDD). Unit tests are written to define the functionality before the code is written. Only when all tests pass is the code considered complete. Proponents argue that it produces software that is both more reliable and less costly than code that is tested by manual exploration. It is considered more reliable because the code coverage is better, and because it is run constantly during development rather than once at the end of a waterfall development cycle. The developer discovers defects immediately upon making a change, when it is least expensive to fix. Finally, code refactoring is safer; transforming the code into a simpler form with less code duplication, but equivalent behavior, is much less likely to introduce new defects.
Graphical User Interface (GUI) testing
A variation on this type of tool is for testing of web sites. Here, web page is the “interface”. Such a framework utilizes entirely different techniques because it is reading HTML instead of observing window events. Another variation is scriptless test automation that does not use record and playback, but instead builds a model of the Application Under Test (AUT) and then enables the tester to create test cases by simply editing the test parameters and conditions. Test-case maintenance is easy, as there is no code to maintain .As the AUT changes the software objects can simply be re-learned or added. It can be applied to any GUI-based software application. The problem with this model is that AUT is actually implemented using test scripts, which have to be constantly maintained whenever there's change to the AUT.
What To Automate
Test automation tools can be expensive, and are usually employed in combination with manual testing. Hence It is not possible to automate everything in the Software. Software systems which are used by a large amount of users simultaneously should be automated. For example, automating test that tests the combinatorial interactions of interdependent parameters at the API level or through the UI makes a lot of sense because the number of combinatorial tests for any complex feature would take much longer to test manually as compared to a 'data-driven' automated test.
When To Automate
Automated tests, that are written before the code, capture the intention of the code, inform design decisions, provide rapid feedback and let the developers know when the code is done. Test automation could also be written after the system code has been written so the automation has to cope with less change. But Automated tests that are written after the code do not directly inform the design nor do they provide rapid feedback. If these tests help us build a better product then they should be written before the code. If we are using automation to do exploratory testing and we intend to throw the automation code away afterwards then we can write the tests later.
Automation Tools
Tools are a driving agent for an automation process. Tools are specifically designed to target some particular test environment, such as Windows and web automation tools, etc. However, an automation framework is an infrastructure that provides the solution where different tools can do their job in a unified manner. This provides a common platform for the automation engineer. Below are few automation tools that are being used in the software industry today:
- HP QuickTest Professional
- IBM Rational Functional Tester
- Rational robot
- WATIR
- Selenium
HP QuickTest Professional is produced by HP Software Division, IBM Rational Functional Tester and Rational robot are produced by IBM Rational and WATIR and Selenium are open source. There are also many other tools which are available.
Disadvantages of Automation
- Creating an automated test is more time-consuming and expensive than running it once manually.
- Proficiency is required to write the automation test scripts.
- Debugging the test script is major issue. If any error is present in the test script, sometimes it may lead to deadly consequences.
- Test maintenance is costly in case of playback methods. Even though a minor change occurs in the GUI, the test script has to be re-recorded or replaced by a new test script.
- Maintenance of test data files is difficult, if the test script tests more screens.
Conclusion
In a nut shell, Test automation is the process of writing a computer program to do testing that would otherwise need to be done manually. Once tests have been automated, they can be run quickly and repeatedly. This is often the most cost effective method for software products that have a long maintenance life, because even minor patches over the lifetime of the application can cause features to break which were working at an earlier point in time. There are many tools available to automate testing.
References
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Additional Reading
- http://guides.rubyonrails.org/migrations.html#anatomy-of-a-migration
- http://www.ibm.com/developerworks/java/library/j-cb08156/index.html
- http://jacqueschirag.wordpress.com/2007/08/12/rants-about-rails-database-migrations
- http://www.oracle.com/technetwork/articles/kern-rails-migrations-100756.html
- Agile Web Development With Rails, Fourth Edition, Sam Rooby, Dave Thomas, David Heinemeier Hansson.