TEST LEVELSRAVEENA SHETTY (86)NAMRATA SHETTY (85)

HEENA SHAIKH (81)FARHIM SHAIKH (80)

TEST LEVELS

UNIT TESTING

DEFINITION Unit Testing is a level of the software

testing process where individual units/components of a software/system 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.

For example, 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.

Component testing may be done in isolation from the rest of the system depending on the context of the development life cycle and the system.

Most often stubs and drivers are used to replace the missing software and simulate the interface between the software components in a simple manner.

A stub is called from the software component to be tested; a driver calls a component to be tested.

METHOD Unit Testing is performed by using the 

White Box Testing method.

UNIT TEST PLAN Prepare Review Rework Baseline

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. In rare cases it may also be performed by independent software testers.

INTEGRATION TESTING

DEFINITION Integration Testing tests interfaces between

computers, interactions to different parts of a system such as an OS, file system and hardware or interfaces between systems.

Integration Testing is a level of the software testing process 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.

EXAMPLE 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.

METHOD 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’.

INTEGRATION TEST PLAN Prepare Review Rework Baseline

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.

Top-down Approach Top down approach tests the

integration from top to bottom, it follows the architectural structure.

Example: Integration can start with GUI and the missing components will be substituted by stubs and integration will go on.

Bottom-up approach In bottom up approach testing takes

place from the bottom of the control flow, the higher level components are substituted with drivers

Big bang approach In big bang approach most or all of

the developed modules are coupled together to form a complete system and then used for integration testing.

SYSTEM TESTING

DEFINITION System Testing is a level of the

software testing process where a complete, integrated system/software is tested.

The purpose of this test is to evaluate the system’s compliance with the specified requirements.

EXAMPLE

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.

METHOD Usually, Black Box Testing method is

used.

SYSTEM TEST PLAN Prepare Review Rework Baseline

When is it performed? System Testing is performed

after Integration Testing and before Acceptance Testing.

Who performs it? Normally, independent Testers perform

System Testing.

ACCEPTANCE TESTING

DEFINITION Acceptance testing is performed after system

testing is done and all or most of the major defects have been fixed.

The goal of acceptance testing is to establish confidence in the delivered software/system that it meets the end user/customers requirements and is fit for use Acceptance testing is done by user/customer and some of the project stakeholders.

Acceptance testing is done in production kind of environment.

For Commercial off the shelf (COTS) software’s that are meant for the mass market testing needs to be done by the potential users, there are two types of acceptance testing for COTS software’s.

• Alpha Testing• Beta Testing

Alpha Testing

Alpha testing is mostly applicable for software’s developed for mass market i.e. Commercial off the shelf(COTS), feedback is needed from potential users.

Alpha testing is conducted at developers site, potential users, members or developers organization are invited to use the system and report defects.

Beta Testing

Beta testing is also know as field testing, it is done by potential or existing users/customers at an external site without developers involvement.

This test is done to determine that the software satisfies the end users/ customer’s needs. This testing is done to acquire feedback from the market.

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