1. Prepared by Stephen M. Thebaut, Ph.D. University of Florida
Course Wrap-Up
Software Testing and Verification
Prepared by
Stephen M. Thebaut, Ph.D.
University of Florida

2. A few loose ends…
Exam 2 + solution notes will be posted (under “Practice Exams”) when all registered students are known to have taken it.
Exam 2 and course grades will be posted on Sakai when available – probably around April 29.

3. A few loose ends… (cont’d)
On-campus students may pick-up their graded exam by appointment shortly after course grades have been posted. Details will be posted on the course website under “Announcements.”
Graded exams for EDGE students will be scanned and posted by UF EDGE shortly after course grades have been posted.
Recall that course grades are based SOLELY on the two exam scores. (Please do not ask if there is some way to improve your grade by doing additional work, etc.)

4. Verification and Validation…
…at the unit/component-level of system development, is what this course is mostly about.
Adds value...by improving product quality and reducing risks.
Three approaches:
Machine-based testing
Human-based testing
Formal correctness proofs

5. Machine-Based Testing
Execution of (“crafted”) test cases
Actual and expected results (i.e., program behaviors) are compared.
Black-Box testing
Partition testing
Combinatorial Approaches
Boundary Value Analysis
Intuition & Experience

6. Machine-Based Testing (cont’d)
White-Box testing
Logic coverage
Dataflow coverage
Path conditions and symbolic evaluation
Fault-based testing
Integration testing techniques
Top-Down
Bottom-Up
Risk Driven
Schedule Driven
Function or Thread Driven

7. Machine-Based Testing (cont’d)
Higher-Level testing
Usability test
Installability test
Serviceability test
Performance test
Stress test
Security test
Software compatibility test
Device and configuration test
Recovery test
Reliability test

8. Human-Based Testing Our focus: Reviews / Inspections
Can be more effective than (machine-based) testing (as demonstrated in many studies).
Applicable to code, design, requirements, testware, publications, etc.
“A (key) ingredient…is consistent and vigorous discipline.”
On the value of Inspections: some can achieve 100:1 ROI; you can expect 10:1 ROI.

9. Formal Correctness Proofs
“pre-condition”
{X≥2}
SP2 := 4
while SP2 <= X
SP2 := SP2 * 2
end_while
{ ( i  SP2 = 2i > X) Л (2(i-1)  X) Л (X = X’) }
loop “invariant”
{ ( i  SP2 = 2i) Л
(2(i-1)  X) Л (X = X’) }
“post-condition”

10. Formal Correctness Proofs (cont’d)
What are the benefits of studying formal verification?
Understanding its limitations.
Deeper insights into programming and program structures.
Criteria for judging both programs and programming languages.
The ability to formally verify small (or parts of large) programs.

11. Formal Correctness Proofs (cont’d)
Bottom line: even if you never attempt to “prove” a program correct outside this course, the study of formal verification should change the way you write and read programs.

12. Formal Correctness Proofs (cont’d)
Axiomatic verification: pre- and post-conditions, ROI’s, weak and strong correctness, synthesizing invariants for loops
Predicate transforms: potential for automation, collapsing infinite expressions for loops, the connection between wp’s and loop invariants
Functional verification: complete and sufficient correctness, the Iteration Recursion Lemma, the Invariant Status Theorem (the connection between program functions and loop invariants)

13. Formal Correctness Proofs (cont’d)
Cleanroom Software Engineering
Intended to make formal verification more practical and effective.
Based on the notion that defects in software should be avoided rather than detected and repaired. (cf. MVQ...)
Uses functional verification – components are not executed or developer-tested!

14. In summary…
V&V techniques have evolved considerably and require specialized knowledge, disciplined creativity, and ingenuity.
Software engineers should be familiar with all V&V techniques, and should be able to employ (and assess the effectiveness of) those that are appropriate to their responsibilities.
An important challenge in SE is to more effectively integrate the V&V techniques currently in use.

15. Prepared by Stephen M. Thebaut, Ph.D. University of Florida
Course Wrap-Up
Software Testing and Verification
Prepared by
Stephen M. Thebaut, Ph.D.
University of Florida