Many programming groups are relying more and more on automated testing, especially groups that use test-driven development. There are many frameworks to write tests in, and continuous integration software will run tests automatically every time code is checked into a version control system.
While automation cannot reproduce everything that a human can do (and all the ways they think of doing it), it can be very useful for regression testing. However, it does require a well-developed test suite of testing scripts in order to be truly useful.
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. Test automation is a 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. 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 two general approaches to test automation:
- Code-driven testing. The public (usually) interfaces to classes, modules, or libraries are tested with a variety of input arguments to validate that the results that are returned are correct.
- Graphical user interface testing. A testing framework generates user interface events such as keystrokes and mouse clicks, and observes the changes that result in the user interface, to validate that the observable behavior of the program is correct.
Test automation tools can be expensive, and it is usually employed in combination with manual testing. It can be made cost-effective in the longer term, especially when used repeatedly in regression testing.
One way to generate test cases automatically is model-based testing through use of a model of the system for test case generation but research continues into a variety of alternative methodologies for doing so.
What to automate, when to automate, or even whether one really needs automation are crucial decisions which the testing (or development) team must make. Selecting the correct features of the product for automation largely determines the success of the automation. Automating unstable features or features that are undergoing changes should be avoided.
Code-driven testing
A growing trend in software development is the use of testing frameworks such as the xUnit frameworks (for example, JUnit and NUnit) that allow the execution of unit tests to determine whether various sections of the code are acting as expected under various circumstances. Test cases describe tests that need to be run on the program to verify that the program runs as expected.
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
Many test automation tools provide record and playback features that allow users to interactively record user actions and replay them back any number of times, comparing actual results to those expected. The advantage of this approach is that it requires little or no software development. This approach can be applied to any application that has a graphical user interface. However, reliance on these features poses major reliability and maintainability problems. Relabelling a button or moving it to another part of the window may require the test to be re-recorded. Record and playback also often adds irrelevant activities or incorrectly records some activities.
A variation on this type of tool is for testing of web sites. Here, the “interface” is the web page. This type of tool also requires little or no software development. However, 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 and then enables the tester to create test cases by simply editing in test parameters and conditions. This requires no scripting skills, but has all the power and flexibility of a scripted approach. Test-case maintenance is easy, as there is no code to maintain and as the application under test changes the software objects can simply be re-learned or added. It can be applied to any GUI-based software application.
What to test
Testing tools can help automate tasks such as product installation, test data creation, GUI interaction, problem detection (consider parsing or polling agents equipped with oracles), defect logging, etc., without necessarily automating tests in an end-to-end fashion.
One must keep satisfying popular requirements when thinking of test automation:
- Platform and OS independence
- Data driven capability (Input Data, Output Data, Meta Data)
- Customizable Reporting (DB Access, crystal reports)
- Easy debugging and logging
- Version control friendly – minimal binary files
- Extensible & Customizable (Open APIs to be able to integrate with other tools)
- Common Driver (For example, in the Java development ecosystem, that means Ant or Maven and the popular IDEs). This enables tests to integrate with the developers’ workflows.
- Support unattended test runs for integration with build processes and batch runs. Continuous Integration servers require this.
- Email Notifications (automated notification on failure or threshold levels). This may be the test runner or tooling that executes it.
- Support distributed execution environment (distributed test bed)
- Distributed application support (distributed SUT)
Framework approach in automation
A framework is an integrated system that sets the rules of Automation of a specific product. This system integrates the function libraries, test data sources, object details and various reusable modules. These components act as small building blocks which need to be assembled to represent a business process. The framework provides the basis of test automation and simplifies the automation effort.
Defining boundaries between automation framework and a testing tool
Tools are specifically designed to target some particular test environment. Such as: Windows automation tool, web automation tool etc. It serves as driving agent for an automation process. However, automation framework is not a tool to perform some specific task, but is an infrastructure that provides the solution where different tools can plug itself and do their job in an unified manner. Hence providing a common platform to the automation engineer doing their job.
There are various types of frameworks. They are categorized on the basis of the automation component they leverage. These are:
- Data-driven testing
- Modularity-driven testing
- Keyword-driven testing
- Hybrid testing
- Model-based testing
Testing tools
Program testing and fault detection can be aided significantly by testing tools and debuggers.
Testing/debug tools include features such as:
- Program monitors, permitting full or partial monitoring of program code including:
- Instruction set simulator, permitting complete instruction level monitoring and trace facilities
- Program animation, permitting step-by-step execution and conditional breakpoint at source level or in machine code
- Code coverage reports
- Formatted dump or symbolic debugging, tools allowing inspection of program variables on error or at chosen points
- Automated functional GUI testing tools are used to repeat system-level tests through the GUI
- Benchmarks, allowing run-time performance comparisons to be made
- Performance analysis (or profiling tools) that can help to highlight hot spots and resource usage
Some of these features may be incorporated into an Integrated Development Environment (IDE).