Software Testing and Quality Assurance Lecture 29 - Introduction to Software Testing

Lecture Outline Introduction to testing types. Testing activities. Introduction to test cases, test oracles and their execution.

Testing Policy Only exhaustive testing can show a program is free from defects. However, exhaustive testing is impossible; Testing policies define the approach to be used in selecting system tests; For example, All functions accessed through menus should be tested; Combinations of functions accessed through the same menu should be tested; Where user input is required, all functions must be tested with correct and incorrect input.

Software Testing & Development Life Cycle Requirements System Testing Integration Testing Architectural Design Unit Testing Detail Design Implementation

Unit Testing module to be tested results software engineer test cases

Unit Testing module to be tested interface local data structures boundary conditions independent paths error handling paths test cases

Unit Testing test cases RESULTS driver Module stub stub interface local data structures Module boundary conditions independent paths error handling paths stub stub test cases RESULTS

Integration Testing Involves building a system from its components and testing it for problems that arise from component interactions. Top-down integration Develop the skeleton of the system and populate it with components. Bottom-up integration Integrate infrastructure components then add functional components. To simplify error localisation, systems should be incrementally integrated.

Integration Testing The Big-bang Approach. Incremental Approach.

Top-Down Integration A top module is tested with stubs B F G stubs are replaced one at a time, "depth first" C as new modules are integrated, some subset of tests is re-run D E

Bottom-Up Integration F G drivers are replaced one at a time, "depth first" C worker modules are grouped into builds and integrated D E cluster

Thread-Based Integration Top modules are tested with stubs B F G C Worker modules are grouped into builds and integrated D E cluster

System Testing System Functional Test System Performance Test Test entire system against the functional requirements. System Performance Test Test the non-functional requirements of the system. For example, Response times, load testing etc. System Acceptance Test Set of tests that the software must pass before it is accepted by the client.

Scenario-based Testing Trivial Example You have been asked to write a term paper on ‘Integration Testing in Component Based System’. To do this, you need to find references from a range of library databases. You logs on to the KFUPM library system and uses the search facility to find relevant papers from IEEE, ACM and Elsevier databases. One paper of special interest requires authentication and you have to fill an online form to receive the paper. If you are allowed, the paper will be downloaded and ready for collection. An email will be send to you once the paper is ready. Scenario-based Testing

Student Activity Identify the possible interactions for the system testing of library system.

Trivial Example - System Testing Test the login mechanism using correct and incorrect login. Test the search facility using queries against known source to check that the search mechanism is actually documents. Test system presentation facility to check that information about documents is displayed properly. Test the mechanism to request permission for downloading. Test the e-mail response indicating that the download document is available.

Need for an automatic test suite execution. Regression Testing Change do not always effect the entire program. Change in one part of system can effect other part. After each change Entire test suite of a system must be run again. Need for an automatic test suite execution.

Test Activities Boils down to selecting and executing test cases. Test case consists of…… Set of test inputs, of if the program is non-terminating, a sequence of test inputs. Expected results when the inputs are executed; and Execution conditions or execution environment in which the inputs are to be executed. These steps generally remain same from unit testing to system testing.

Test Case Selection Coverage criterion; Equivalence Partitioning Boundary-Value Analysis Coverage-Based Testing Control-flow Data-flow Expected behavior of every test input to be generated. (Test Oracles) Testing environment.

Difficult to automate or to assess their quality Test Oracles Determines whether or not the program has passed or failed the test case. A test oracle is A program A process A body of data In many cases - directly form the requirements. For example, a test case assessing performance - performance threshold. Difficult to automate or to assess their quality

Generally can be automated to an extend !!!! Test Execution Test inputs on the ‘program-under-test’ Record the actual behavior. Generally can be automated to an extend !!!!

Generally can be automated to an extend !!!! Test Evaluation Compare the actual behavior with the expected behavior. Generally can be automated to an extend !!!!

Generally can be automated to an extend !!!! Test Reporting Report the outcome of the testing. Developers Project Mangers etc. Generally can be automated to an extend !!!!

Key Points A system typically undergoes a range of testing types. Each type of testing is aimed at detecting different kinds of failures. Testing boils down to the selection and execution of test cases.