Sdd Testing & Evaluating
- 1. Testing and Evaluating Software Design and Development Chapter 6 summary
- 2. Contents Testing the Software Comparison of the Solution with the original Design Specification Generating relevant Test Data for Complex Solutions Levels of Testing Live Test Data Benchmarking Quality Assurance Reporting on the Testing Process Documentation Communication
- 3. Testing the Software Solution Testing is carried out to find errors Software developers must continually ensure that the original specifications are being met in the software product being developed Construction of appropriate test data and adequate testing prevents the occurrence of major problems in the finished program that are expensive to fix. Test data must be sufficient to ensure the program is completely operational and free of logic errors. Test data must be constructed to test every part of a program, including the mainline of the program and any modules used by the program.
- 4. What should be tested? Test data should test All parts of the program Each path of execution - test data should be sufficient to test the termination and correct exit of each loop. To test each path in nested If statement / CASE structure. Boundary conditions - the values of variables or expressions that determine the choice of available options to be taken. example At the very minimum to execution paths should always be tested rather than boundary conditions. Large programs should be tested using other testing mechanisms. Testing should include :Unit testing, program testing and system testing
- 5. Unit or Module Testing Structured programming results in modules, each of which can be tested individually Subprograms can be tested as a black box where data is entered and results are shown. In black box testing, only the inputs and outputs are checked. The processes that achieve these results are ignored. Subprograms can also be tested as a white box where the algorithm of the subprogram is understood and each path of execution can be tested appropriately. White box testing examines all the data paths in a module. A driver program may be developed to test modules in a program. The driver substitutes for the main program, calling the subprogram and supplying the necessary values for any variables. A driver is a temporary section of code that is created to test an individual procedure or module by calling it up and executing it.
- 6. Program Testing It is a minimum requirement that the test data tests each logical pathway and program branch that can be entered. All modules are called and executed at least once or when expected This way, the entire program can be completely tested. Screen elements such as menus and buttons must be tested to ensure they are functioning correctly.
- 7. System Testing During system testing, the program is tested in a variety of operating environments. The software may function in the development system or a controlled environment however, when implemented on the users computer, problems may arise. The effect of hardware, operating systems and other software may create errors that have not been previously detected. System testing is carried out to detect errors at the software / hardware interface, Carried out by users rather than developers. System tests treat the program as a black box.
- 8. Live Test Data Live data is real data, used to ensure that a program works under real-life conditions. Real data is supplied by the client or can be generated by CASE tools. Stress testing involves increasing the load on a program in an attempt to make it fail. Live Test Data should include: Larger File Sizes Mix of Transaction Types Response Times Volume data Interfaces between Modules Comparison with Program Test Data
- 9. Live data is used to ensure that the system response times are appropriate. Response times are dependent on all the system components, together with their interactions with each other and other processes that may be occurring concurrently. Response times should be tested on minimum hardware using typical data of different types. Interface tests will ensure that the correct numbers of parameters are sent to and from the module and that the format is correct. Interface tests will also detect conflicts between local and global variables. A variety of different transaction types and sequences of data entry should be tested with live data. Module and program testing usually involve testing specific transactions or processes one at a time. During system testing, transactions occur in random order and checked to see if any errors arise Software developers generate test data to test the limits of the system that may not be tested under normal use. (to ensure the system has scalability) A program developed to access files should be tested with a range of file types and sizes. The use of large files will highlight problems associated with data access.
- 10. Benchmarking A benchmark is a standard against which performance of a computer program can be assessed against expected outcomes and other similar products on the market. Established programs are often used as a benchmark to indicate the quality and performance expectations of a new product. Benchmarks allow users of software products to make informed purchasing decisions
- 11. Quality Assurance Quality Assurance is a set of procedures used to certify that a generated product meets specified criteria with respect to quality and reliability. Correctness - Does it do what it is supposed to do? Reliability - Does it do it all of the time? Efficiency - Does it do it the best way possible? Integrity - Is it secure? Maintainability - Can it be understood? (CREIM) Quality Assurance is not just about testing a product once it has been completed. Its about periodically performing inspections, reviews and tests on the system being developed. Quality assurance techniques should be implemented throughout the software development process.
- 12. Alpha & Beta Testing Alpha Testing Testing of the final solution by personnel within the software development company prior to the product’s release. The client uses the system in a controlled environment and checks to see if it meets their requirements. Beta Testing(Acceptance Testing) Testing of the final solution by a limited number of users outside the software development company using real world data and conditions. The program is given to a number of potential clients who will also report to the developers any problems they encounter in the program.
- 13. Reporting on the Testing Process Required Documentation A test data table should be created to show the test data to be used and the reason why this item of test data was selected. Test requirements - What needs to be tested? Test plan - How do we implement these tests? Test data and expected results - What are the necessary inputs and the expected outputs? Test results - Do the actual results match the expected results? Recommendations - What needs to be done now
- 14. A desk-check table is used to document the test data used and compare the expected output with the actual output of the algorithm or program. CASE Tools that aid in the testing process: Tools to generate or acquire data to be used during testing Tools that analyse the source code Simulation tools to mimic the roles of hardware or other software that interacts with the program
- 15. Communication Independent testers are less likely to approach the program with preconceptions. It is essential that the user is provided with the opportunity to evaluate the solution that has been developed. Results of the testing provides an opportunity for the users to evaluate and discuss the functionality of the new system. Alpha and Beta testing help to provide users with the opportunity to use the program. After the customer has approved a program, it can be released to the general market.
- 16. The End
- 17. Boundary Conditions CASEWHERE age is <=3: output “Too young for school” <=18: output “Could be at school” OTHERWISE: output “Too old for school” ENDCASE An appropriate set of data could therefore be 2 3 18 20. Back
- 18. Black box Testing Back
- 19. White box Testing Back