2.  Software Testing Software Testing  Characteristics of Testable Software Characteristics of Testable Software  A Testing Life Cycle A Testing Life Cycle  Validation and Verification Validation and Verification  Terminology Terminology  Classification of Test Classification of Test  Test phases Test phases  Two Unit Testing Techniques Two Unit Testing Techniques

3.  Program testing can be a very effective way to show the presence of bugs, but it is hopelessly inadequate for showing their absence  Testing is obviously concerned with errors, faults, failures and incidents. A test is the act of exercising software with test cases with an objective of  Finding failure  Demonstrate correct execution BACK

4.  Operable ◦ The better it works (i.e., better quality), the easier it is to test  Observable ◦ Incorrect output is easily identified; internal errors are automatically detected  Controllable ◦ The states and variables of the software can be controlled directly by the tester  Decomposable ◦ The software is built from independent modules that can be tested independently

5.  Simple ◦ The program should exhibit functional, structural, and code simplicity  Stable ◦ Changes to the software during testing are infrequent and do not invalidate existing tests  Understandable ◦ The architectural design is well understood; documentation is available and organized BACK

6. Requirement Specs Design Coding Testing Fault Resolution Fault Isolation Fault Classification Error Fault Error incident Fix BACK

7.  Error ◦ Represents mistakes made by people  Fault ◦ Is result of error. May be categorized as  Fault of Commission – we enter something into representation that is incorrect  Fault of Omission – Designer can make error of omission, the resulting fault is that something is missing that should have been present in the representation BACK

8.  Verification - typically involves reviews and meeting to evaluate documents, plans, code, requirements, and specifications. This can be done with checklists, issues lists, walkthroughs, and inspection meeting. Verification: “you built it right”  Validation - typically involves actual testing and takes place after verifications are completed. Validation: “you built the right thing Validation and Verification process continue in a cycle till the software becomes defects free. BACK Verification and validation

9.  There are two levels of classification  One distinguishes at granularity level  Acceptance Testing  Unit level  Integration level  System level  Regression Testing  Other classification (mostly for unit level) is based on methodologies  Black box (Functional) Testing  White box (Structural) Testing BACK

10.  Acceptance Testing – this checks if the overall system is functioning as required.  Unit testing – this is basically testing of a single function, procedure, class.  Integration testing – this checks that units tested in isolation work properly when put togheter.  System testing – here the emphasis is to ensure that the whole system can cope with real data, monitor system performance, test the system’s error handling and recovery routines.  Regression Testing  Regression Testing – this checks that the system preserves its functionality after maintenance and/or evolution tasks.

11.  Black-box testing ◦ Knowing the specified function that a product has been designed to perform, test to see if that function is fully operational and error free ◦ Includes tests that are conducted at the software interface ◦ Not concerned with internal logical structure of the software  White-box testing ◦ Knowing the internal working of a product ◦ Involves tests that concentrate on close examination of procedural detail ◦ Logical paths through the software are tested ◦ Test cases exercise specific sets of conditions and loops BACK

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