LECTURE 6 LEVELS OF SOFTWARE TESTING

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1 LECTURE 6 LEVELS OF SOFTWARE TESTING UNIT TESTING Unit testing is a level of software testing where individual units/ components of software are tested. The purpose is to validate that each unit of the software performs as designed. A unit is the smallest testable part of software. It usually has one or a few inputs and usually a single output. In procedural programming a unit may be an individual program, function, procedure, etc. In object-oriented programming, the smallest unit is a method, which may belong to a base/ super class, abstract class or derived/ child class. Unit testing frameworks, drivers, stubs, and mock/ fake objects are used to assist in unit testing. Unit testing: See component testing. Component testing: The testing of individual software components. Unit testing is performed by using the White Box Testing method. When is it performed? Unit testing is the first level of testing and is performed prior to Integration Testing. Who performs it? Unit Testing is normally performed by software developers themselves or their peers. Prepared by: Engr. M. Nadeem Page 1

2 In rare cases it may also be performed by independent software testers. INTEGRATION TESTING Integration Testing is a level of software testing where individual units are combined and tested as a group. The purpose of this level of testing is to expose faults in the interaction between integrated units. Test drivers and test stubs are used to assist in Integration Testing. Integration testing: Testing performed to expose defects in the interfaces and in the interactions between integrated components or systems. See also component integration testing, system integration testing. Component integration testing: Testing performed to expose defects in the interfaces and interaction between integrated components. System integration testing: Testing the integration of systems and packages; testing interfaces to external organizations (e.g. Electronic Data Interchange, Internet). Analogy During the process of manufacturing a ballpoint pen, the cap, the body, the tail and clip, the ink cartridge and the ballpoint are produced separately and unit tested separately. When two or more units are ready, they are assembled and Integration Testing is performed. For example, whether the cap fits into the body or not. Any of Black Box Testing, White Box Testing, and Gray Box Testing methods can be used. Normally, the method depends on your definition of unit. When is Integration Testing performed? Integration Testing is performed after Unit Testing and before System Testing. Who performs Integration Testing? Either Developers themselves or independent Testers perform Integration Testing. Approaches Big bang is an approach to Integration Testing where all or most of the units are combined together and tested at one go. This approach is taken when the testing team receives the entire software in a bundle. So what is the difference between Big Bang Integration Testing and System Testing? Well, the former tests only the interactions between the units while the latter tests the entire system. Prepared by: Engr. M. Nadeem Page 2

3 Top Down is an approach to Integration Testing where top level units are tested first and lower level units are tested step by step after that. This approach is taken when top down development approach is followed. Test Stubs are needed to simulate lower level units which may not be available during the initial phases. Bottom Up is an approach to Integration Testing where bottom level units are tested first and upper level units step by step after that. This approach is taken when bottom up development approach is followed. Test Drivers are needed to simulate higher level units which may not be available during the initial phases. Sandwich/Hybrid is an approach to Integration Testing which is a combination of Top Down and Bottom Up approaches. Example- checking that a Payroll system interacts as required with the Human Resource system. SYSTEM TESTING System Testing is a level of the software testing where complete and integrated software is tested. The purpose of this test is to evaluate the system s compliance with the specified requirements. System testing: The process of testing an integrated system to verify that it meets specified requirements. Analogy During the process of manufacturing a ballpoint pen, the cap, the body, the tail, the ink cartridge and the ballpoint are produced separately and unit tested separately. When two or more units are ready, they are assembled and Integration Testing is performed. When the complete pen is integrated, System Testing is performed. Usually, Black Box Testing method is used. When is it performed? System Testing is performed after Integration Testing and before Acceptance Testing. Who performs it? Normally, independent Testers perform System Testing. Prepared by: Engr. M. Nadeem Page 3

4 ACCEPTANCE TESTING Acceptance Testing is a level of the software testing where a system is tested for acceptability. The purpose of this test is to evaluate the system s compliance with the business requirements and assess whether it is acceptable for delivery. Acceptance testing: Formal testing with respect to user needs, requirements, and business processes conducted to determine whether or not a system satisfies the acceptance criteria and to enable the user, customers or other authorized entity to determine whether or not to accept the system. Analogy During the process of manufacturing a ballpoint pen, the cap, the body, the tail and clip, the ink cartridge and the ballpoint are produced separately and unit tested separately. When two or more units are ready, they are assembled and Integration Testing is performed. When the complete pen is integrated, System Testing is performed. Once System Testing is complete, Acceptance Testing is performed so as to confirm that the ballpoint pen is ready to be made available to the end-users. Usually, Black Box Testing method is used in Acceptance Testing. Testing does not normally follow a strict procedure and is not scripted but is rather ad-hoc. When is it performed? Acceptance Testing is performed after System Testing and before making the system available for actual use. Who performs it? Internal Acceptance Testing (Also known as Alpha Testing) is performed by members of the organization that developed the software but who are not directly involved in the project (Development or Testing). Usually, it is the members of Product Management, Sales and/or Customer Support. External Acceptance Testing is performed by people who are not employees of the User Acceptance Testing (Also known as Beta Testing) is performed by the end users of the software. They can be the customers themselves or the customers customers. Prepared by: Engr. M. Nadeem Page 4

5 DIFFERENCE BETWEEN SYSTEM TESTING AND ACCEPTANCE TESTING: System Testing 1. System Testing does not include any thing means it is not known by any other name. Acceptance Testing 1. Acceptance Testing Include Alpha Testing means it is also sometimes known as alpha testing. 2. User is not involved in System Testing. 2. User is completely involved in Acceptance Testing. 3. It is performed before Acceptance Testing. 3. It is performed after System Testing. 4. It is not the final stage of Validation. 4. It is the final stage of Validation. 5. System testing of software or hardware is testing conducted on a whole, integrated system to estimate the systems compliance with its specified set of requirements? 6. The only things Tester should be testing at the System Test stage are things that he and she couldn t test before. 7. It is done to check how the system as a whole is functioning. Here the functionality and performance of the system is validated. 5. Acceptance Testing of software or hardware is testing conducted to evaluate the system compliance with its specified set of user requirements. 6. The only things Developer and User should be testing at the Acceptance Test stage are things that developer and tester couldn t test before. 7. It is done by the developer before releasing the product to check whether it meets the requirements of user or not and it is also done by the user to check whether I have to accept the product or not. 8. It is used to check whether the system meets the defined Specifications or not. 9. System Testing refers to the testing of complete system as a whole that is carried out by testers and sometimes by developers to check whether it meets the system specifications or not. 10. System Testing determine the developer and tester for satisfaction with system specifications. 11. System Testing involves both Functional and Non- Functional Testing. 8. It is used to check whether it meets the defined User Requirements or not. 9. Acceptance Testing is carried out by the users to determine whether they accept the delivery of the system or not. It is normally performed by users and sometimes developers are also involved in it. 10. Acceptance Testing determine the customer for satisfaction with software product. 11. Acceptance Testing only involves the Functional Testing based on the requirement given by client/user. Prepared by: Engr. M. Nadeem Page 5

6 Note: System Testing: The process of testing an integrated system to verify that it meets specified requirements is known as system testing. Acceptance Testing: After the system testing is over, the software/application is tested by the client/user to check whether it meets the requirements given by him or not. This is known as acceptance testing. Acceptance testing can be performed either at the developer s site (premises) or client site. BEST DIFFERENCE BETWEEN ALPHA AND BETA TESTING Alpha Testing 1. It is always performed by the developers at the software development site. 2. Sometimes it is also performed by Independent Testing Team. 3. Alpha Testing is not open to the market and public 4. It is conducted for the software application and project. 5. It is always performed in Virtual Environment. 6. It is always performed within the organization. Beta Testing (Field Testing) 1. It is always performed by the customers at their own site. 2. It is not performed by Independent Testing Team. 3. Beta Testing is always open to the market and public. 4. It is usually conducted for software product. 5. It is performed in Real Time Environment. 6. It is always performed outside the organization. 7. It is the form of Acceptance Testing. 7. It is also the form of Acceptance Testing. 8. Alpha Testing is definitely performed and carried out at the developing organizations location with the involvement of developers. 9. It comes under the category of both White Box Testing and Black Box Testing. 10. Alpha Testing is always performed at the time of Acceptance Testing when developers test the product and project to check whether it meets the user requirements or not. 8. Beta Testing (field testing) is performed and carried out by users or you can say people at their own locations and site using customer data. 9. It is only a kind of Black Box Testing. 10. Beta Testing is always performed at the time when software product and project are marketed. Prepared by: Engr. M. Nadeem Page 6

7 11. It is always performed at the developer s premises in the absence of the users. 12. Alpha Testing is not known by any other different name. 13. It is considered as the User Acceptance Testing (UAT) which is done at developer s area. 11. It is always performed at the user s premises in the absence of the development team. 12 Beta Testing is also known by the name Field Testing means it is also known as field testing. 13. It is also considered as the User Acceptance Testing (UAT) which is done at customers or users area. DIFFERENCE BETWEEN SYSTEM TESTING AND INTEGRATION TESTING But apart from that before you take a look at differences first of all take a brief look at above than go for differences. System Testing 1. In system testing we test the complete system as a whole to check whether the system is properly working or not means as per the requirements or not. 2. In system testing testers always have to concentrate on both functional and nonfunctional testing like performance, load, stress, security, recovery testing and so on. 3. For performing this testing system must be integrated tested. 4. It starts from the requirements specifications. 5. System Testing does not test the visibility of code. 6. It does not require any frame means scaffolding. 7 In System Testing Tester pays attention to the system functionality. 8. It pays attention to the system functionality. 9. It is always only the kind of Black Box Testing. Integration Testing 1. In integration testing we test the modules to see whether they are integrating properly or not by combining the modules and tested as a group. 2. In integration testing testers have to concentrate on functional testing means main focus on how two modules are combined and tested as a group. 3. For performing this testing system must be unit tested before. 4. It starts from the interface specification. 5. Integration Testing test the visibility of the integration structure. 6. It requires some frame means scaffolding. 7. In Integration Testing Tester pays attention to the integration among modules. 8. It pays attention to the Integration among modules. 9. It is a kind of both White Box Testing and Black Box Testing. Prepared by: Engr. M. Nadeem Page 7

A Review Paper on Software Testing

A Review Paper on Software Testing Amit M. Kale 1, Vivek V. Bandal 2, Komal Chaudhari 3 1,2Bachelor Student, Dept. of Electrical Engineering 3Professor, Dept. of Computer Engineering ----------------------------------------------------------------------***---------------------------------------------------------------------