SystemTesting

1. SystemTesting S. R. Roy

2. Why testing? • Thorough testing is key to the success of the system. • A small undetected error in a system may conceivably explode into a very large problem, that may prove verycostly. Effective testing unearths such errors. • Another reason for system testing is to ensure its utility to users- the best of programs are worthless if they do not meet user expectations. Unfortunately, user’s demand is often compromised by efforts to program or design efficiency in terms of processing time, memory requirements etc.

3. What do we test for? • A software is tested to ensure its • correctness, • completeness, • its behaviour at pick load, • its ability to recover from failure, • usability of its documents and procedures.

4. What do we test for? • Online response : response time of a software should not cause hardship to the user. In order to ensure this input is given from as many terminals as would normally be used in peak hours. • Stress testing : purpose is to establish that the system would not break down or malfunction at peak loads. System is subjected to high volume of data over a short time period.

5. What do we test for? • Volume testing : used to ensure the correct functioning using test data. • Recovery & security : a forced system failure is induced to test for the backup and recovery procedures. • Usability of documents & procedures : User’s documents are meant to guide users. User friendliness of these documents determines the acceptability of a system. It largely depends on the ease with which user can carry-out functions and fix problems by referring to these manuals.

6. Test data • The proper choice of test data is as important as the test itself. • If the test data as inputs are not valid or the representative of the data to be provided by the user then the probability of correct output is suspect.

7. Test data • Artificial test data provides all combinations of values and formats to test all functions. Also provides extreme values for testing the limits of the software. • Live data: These are taken from the actual databases. These provide the data that are to be handled by the software during actual transactions.

8. Inputs causing anomalous I beha viour e S ystem Outputs w hich r e v eal the pr esence of Output test results O defects e Types of tests • Black box testing : to ensure whether or not expected outputs are delivered. Input test data

9. Types of tests White box testing : for knowing internal working of different parts, test various parts, if exhaustivetesting is impossible, then test high-risk parts only.

10. Steps in testing • System testing consists of the following steps. • Program testing: it checks for two types of errors: • Syntax and • Logic • Syntax error is a program statement that violets one or more rules of the language. • A logic error deals with incorrect data fields, out-of-range items etc. • During program testing actual output is compared with the expected output.

11. Steps in testing • String testing: Software consists of many modules. Each module is to accomplish its functions in relation to other modules. String test ensures this. • System testing: it is designed to uncover weaknesses that were not detected in earlier tests. This includes forced system failures and behaviour of the system in actual operational environment. • User acceptance testing: It verifies the system’s procedures operate as per specifications, the data integrity is ensured, user documents and manuals are usable. It also ensures motivation of users.