Testing Overview

Verification of the behavior of a program

Against inspected behaviour

Infinite

destructive

• Uncover undiscovered defects
• Not exhaustive for reasonably sized software

It's expensive

Uncover different classes of errors in a minimum amount of time with a minimum amount of effort

• Uncover different classes of errors
• Prove system works as stated/expected
• Provide information about software's reliability and quality

• 1. Presence
• 2. Abscence

• 1. Tasks not fully understood/defined
• 2. Not enough time
• 3. Third party errors (buggy tools, premade software)
• 4. Failure to use source control

Bad requirements

• Bad schedules
• Late design changes

• Typographical errors (effectively random)
• Errors in logic/assumptions (usually prevent execution so are quickly discovered)

• Assuming an odd or unlikely logical path will not be executed
• Subconscious assumptions about control flow and data design

Faults cause failures

Some command performed multiplication instead of addition (expected)

No condition for + in switch, causing the base case to occur unexpectedly

• Algorithmic
• Syntax
• Computation/Precision
• Documentation
• Stress/Overload
• Capacity/Boundary
• Timing/Coordination
• Throughput/Performance
• Recovery
• Hardware/System Software

Algorithm produces incorrect result for given input

Improper use of programming language constructs

Formula implementation is wrong or has incorrect accuracy

Documentation doesn't match software

Going outside of program limits (exceed array size or overflow integer)

Code handling coordination of event systems is inadequate (real-time systems)

System does not perform to the required speed

When a failure occurs and the system no longer behaves correctly

Supporting software/hardware does not behave as expected