National 5 Computing Science Testing

1. Testing

2. Testing
Testing begins at the analysis and design stages,
with prototypes being developed
It is much more cost effective to fix problems at
earlier stages of the software development process

3. Testing
The purpose of testing is to
to identify errors
to ensure that software is fit for purpose
to ensure that code is efficient
to ensure that code is maintainable

4. Test plan
Selecting appropriate test data sets is important, so we
need to create a test plan
Expected results should be known in advance (so the
actual output can be checked against expected output)

5. Test Data Sets
Normal
Extreme
Exceptional

6. Test Data Sets
Normal Data
A normal data set should be tested to show that the
program works as expected.

7. Test Data Sets
Extreme Data
Extreme data is used to test the boundary limits within
a program.

8. Test Data Sets
Exceptional Data
Exceptional data is used to test that the program can
properly handle unexpected inputs.

9. Comprehensive testing
Software should undergo comprehensive testing
This means testing against a range of normal,
exceptional and extreme data
It does not mean running a program a couple of times
to find that it works OK.

10. Phases of testing
1. Procedure / Module Testing
Individual code procedures and modules tested
2. Integration Testing
Test the modules work together
3. System Testing
Test overall system
4. Acceptance Testing
Customer tests program against their specification
5. Alpha and Beta Testing
Put the software out to users to test

11. Who tests?
Initially, tests are carried out by the development team
Acceptance testing is carried out by the client
The final alpha and beta test are carried out by a select
band of users. It is becoming common for software beta
programs to be freely downloadable

12. Syntax Errors
Syntax errors are errors which appear in your code
and can be misspelled keywords or using the
language incorrectly
Often software development environments will
highlight syntax errors for you
Syntax errors are the most common type of errors

13. Syntax Errors

14. Run-time (execution) Errors
Run-time errors are those that appear when you run
your code
The syntax is correct, but the program fails to
execute

15. Run-time (execution) Errors

16. Logic Errors
Logic errors are those that appear when the program
is running
They will not cause the program to crash but will
produce unwanted or unexpected results

17. Logic Errors

18. Testing removes all bugs...
...wrong!
Testing can only convince us of the presence of errors,
and not of their absence.
Testing can never prove conclusively that a program is
correct. No matter how exhaustive the testing, it will
always be possible for the system to contain errors
which have not been detected.