Levels Of Testing

There are four levels of testing

Unit Testing
Integration Testing
System Testing
User Acceptance Testing

Unit Testing
A unit is smallest testable piece of software


–can be compiled, linked, loaded

–e.gfunctions/procedures, classes, interfaces

–normally done by programmer

–Test cases written after coding
 
Buddy Testing


Team approach to coding and testing

One programmer codes the other tests and vice versa

Test cases ‐written by tester(beforecoding starts). Better than single worker approach

Objectivity

cross‐training

Models program specification requirement
Normally in programmers IDE (comfort zone)


Find unit bugs

Wrong implementation of functional specs

Testing function procedures e.g. the ValidatePIN() procedure

Integration Testing

Test for correct interaction between system units


•systems ‐built by merging existing libraries

•modules coded by different people

•Mainly tests the interfaces among units

•Bottom up integration testing

•Use of drivers

•Top down integration testing

•Use of stubs
 
Who does integration testing and when is it done?


•Done by developers/testers

•Test cases written when detailed specification is ready

•Test continuous throughout project

•Where is it done?

•done on programmer’s workbench

•Why is it done?

•Discover inconsistencies in the combination of units.
 
System Testing
 
Test of overall interaction of components


•Find disparities between implementation and specification

•Usually where most resources go to

•Involves –load, performance, reliability and security testing
 
Who performs system testing and when is it done?


–Done by the test team

–Test cases written when high level design spec is ready

•Where is it done?

–Done on a system test machine

–Usually in a simulated environment e.g. vmware
 
User Acceptance Testing
 
•Demonstrates satisfaction of user


•Users are essential part of process

•Usually merged with System Testing

•Done by test team and customer

•Done in simulated environment/real environment