Types of Testing

24 March, 2014
The testing types are classified as below:

1. Unit testing: In computer programming, unit testing is a procedure used to validate that individual modules or units of source code are working properly. A unit test is a test for a specific unit. Ideally, each test case is independent from the others; mock objects can be used to assist testing a module in isolation. Unit testing is typically done by the developers and not by end-users. The goal of unit testing is to isolate each part of the program and show that the individual parts are correct. Unit testing provides a strict, written contract that the piece of code must satisfy. As a result, it affords several benefits.

2. Integration testing: Integration testing (sometimes called Integration and Testing, abbreviated I&T) is the phase of software testing in which individual software modules are combined and tested as a group. It follows unit testing and precedes system testing.

Integration testing takes as its input modules that have been unit tested, groups them in larger aggregates, applies tests defined in an integration test plan to those aggregates, and delivers as its output the integrated system ready for system testing. The purpose of integration testing is to verify functional, performance and reliability requirements placed on major design items. These "design items", i.e. assemblages (or groups of units), are exercised through their interfaces using Black box testing, success and error cases being simulated via appropriate parameter and data inputs. Simulated usage of shared data areas and inter-process communication is tested, individual subsystems are exercised through their input interface. All test cases are constructed to test that all components within assemblages interact correctly, for example, across procedure calls or process activations, and is done after the testing single module i.e. unit testing.The overall idea is a "building block" approach, in which verified assemblages are added to a verified base which is then used to support the Integration testing of further assemblages.
The different types of integration testing are big bang, top-down, bottom-up, and back bone.

3. System testing is testing conducted on a complete, integrated system to evaluate the system's compliance with its specified requirements. System testing falls within the scope of Black box testing, and as such, should require no knowledge of the inner design of the code or logic. System testing takes, as its input, all of the "integrated" software components that have successfully passed Integration testing and also the software system itself integrated with any applicable hardware system(s). The purpose of Integration testing is to detect any inconsistencies between the software units that are integrated together (called assemblages) or between any of the assemblages and the hardware. System testing is a more limiting type of testing; it seeks to detect defects both within the "inter-assemblages" and also within the system as a whole.

4. Acceptance testing is performed by the customer on a system prior to the customer accepting delivery or accepting transfer of ownership of that system. For systems, it is performed exclusively through black-box testing. Acceptance testing is also performed on lots (mechanical parts) or batches (chemicals) of manufactured or produced items. Acceptance testing generally involves running a suite of tests on the completed system. Each individual test, known as a case, exercises a particular operating condition of the user's environment or feature of the system, and will result in a pass or fail boolean outcome. There is generally no degree of success or failure. The test environment is usually designed to be identical, or as close as possible, to the anticipated user's environment, including extremes of such. The acceptance test suite is run against the supplied input data or using an acceptance test script to direct the testers. Then the results obtained are compared with the expected results. If there is a correct match for every case, the test suite is said to pass. If not, the system may either be rejected or accepted on conditions previously agreed between the sponsor and the manufacturer.
The objective is to provide confidence that the delivered system meets the business requirements of both sponsors and users. The acceptance phase may also act as the final quality gateway, where any quality defects not previously detected may be uncovered.

5. Performance testing: In software engineering, performance testing is testing that is performed to determine how fast some aspect of a system performs under a particular workload. Performance testing can serve different purposes. It can demonstrate that the system meets performance criteria. It can compare two systems to find which performs better. Or it can measure what parts of the system or workload cause the system to perform badly. In the diagnostic case, software engineers use tools such as profilers to measure what parts of a device or software contribute most to the poor performance or to establish throughput levels (and thresholds) for maintained acceptable response time. It is critical to the cost performance of a new system, that performance test efforts begin at the inception of the development project and extend through to deployment.

6. Stress testing is a form of testing that is used to determine the stability of a given system or entity. It involves testing beyond normal operational capacity, often to a breaking point, in order to observe the results.

7. Load testing is the process of creating demand on a system or device and measuring its response. Load testing generally refers to the practice of modeling the expected usage of a software program by simulating multiple users accessing the program's services concurrently. As such, this testing is most relevant for multi-user systems, often one built using a client/server model, such as web servers. However, other types of software systems can be load-tested also. When the load placed on the system is raised beyond normal usage patterns, in order to test the system's response at unusually high or peak loads, it is known as stress testing. The load is usually so great that error conditions are the expected result, although no clear boundary exists when an activity ceases to be a load test and becomes a stress test. The term is often used synonymously with performance testing, reliability testing, and volume testing.

8. Sanity test: A sanity test or sanity check is a basic test to quickly evaluate the validity of a claim or calculation, specifically a very brief run-through of the functionality of a computer program, system, calculation, or other analysis, to assure that the system or methodology works as expected, often prior to a more exhaustive round of testing. Sanity tests are sometimes mistakenly equated to smoke tests. Generally, a smoke test is scripted (either using a written set of tests or an automated test), whereas a sanity test is usually unscripted. The process of sanity testing begins with the execution of some online transactions of various modules, batch programs of various modules to see whether the software runs without any hindrance or abnormal termination. This practice can help identify most of the environment related problems.

9. Smoke testing is done by developers before the build is released or by testers before accepting a build for further testing.In software engineering, a smoke test generally consists of a collection of tests that can be applied to a newly created or repaired computer program. Sometimes the tests are performed by the automated system that builds the final software. In this sense a smoke test is the process of validating code changes before the changes are checked into the larger product’s official source code collection. Next after code reviews, smoke testing is the most cost effective method for identifying and fixing defects in software; some even believe that it is the most effective of all.
In software testing, a smoke test is a collection of written tests that are performed on a system prior to being accepted for further testing. This is also known as a build verification test. This is a "shallow and wide" approach to the application. The tester "touches" all areas of the application without getting too deep, looking for answers to basic questions like, "Can I launch the test item at all?", "Does it open to a window?", "Do the buttons on the window do things?". There is no need to get down to field validation or business flows. If you get a "No" answer to basic questions like these, then the application is so badly broken, there's effectively nothing there to allow further testing. These written tests can either be performed manually or using an automated tool. When automated tools are used, the tests are often initiated by the same process that generates the build itself.

10. Regression testing is any type of software testing which seeks to uncover regression bugs. Regression bugs occur whenever software functionality that previously worked as desired stops working or no longer works in the same way that was previously planned. Typically regression bugs occur as an unintended consequence of program changes.
Common methods of regression testing include re-running previously run tests and checking whether previously fixed faults have reemerged. In most software development situations it is considered good practice that when a bug is located and fixed, a test that exposes the bug is recorded and regularly retested after subsequent changes to the program. Although this may be done through manual testing procedures using programming techniques, it is often done using automated testing tools. Such a 'test suite' contains software tools that allows the testing environment to execute all the regression test cases automatically; some projects even set up automated systems to automatically re-run all regression tests at specified intervals and report any regressions. Regression testing can be used not only for testing the correctness of a program, but it is also often used to track the quality of its output.

For the complete list of different types of testig, please refer to http://www.automationace.com/2014/04/different-types-of-testing.html

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