CSE565: Software Validation, Verification and Testing
Department of Computer Science and Engineering Ira A. Fulton School of Engineering
Arizona State University

 

This are my notes for the eighth class session:

1. Structure-Based Testing (White Box Testing)

• A white box testing methods gets its name due the fact it see the code. Unlike black box testing methods that are all based only in requirements.
• Tend to be techniques to be applied into lower level (small units of code) unit, services, components.
• Not for entire systems
• Not fot Integration or Qualification Level of Testing

There are two categories of structure-based Testing (white box testing): static techniques and dynamic techniques.

1.1. Static Techniques

Analysis of the code. Example: symbolic execution.

1.2. Dynamic Techniques

Execute the code: run for test. There are two types of dynamic techniques:

• Structure or control flow.
  • Statement coverage
  • Decision coverage
  • Decision-Condition Coverage
  • Multiple decision Coverage
• Data flow

2. Statement Coverage

Develop test cases such that every statement is execute at least once.

• Example:
  
  if a <10 or b>5
  (1) then x<-50 (2) else x <-0; if w = 5 or y>0
  (3) then z<-48 (4) else z<-5;

• Flow Chart = Control Flow Diagram.
  Test predicate (diamond)
  Statement (oval)
• 4 statement in the previous code.
• Path Testing to execute every Path into the code!
  Testing strategy execute all path into the code
  

• Loops are going to make the numbers of paths bigger. So path coverage is complicate.
• Values of (a, b, w, y) to execute all statements (with 2 cases we do it)!

  a = 0, b=0, w=0, y=0 (execute 1 and 4)
  a=10, b=4, w=5, y = don’t care (execute 2 and 3)

  Whit these two tests cases we are covering all the statements.

• However, this kind of testing is the minimum need.
  FAA D0178B standard / best practices:
  1. statements 100% statement coverage!
• Compilers help us to do that. By example the PROFILER measure the time of each statement.

3. Decision (branch) Coverage

• Develop test cases such that each branch (decision point) is executed at least once.
• Decision point -> conditional statement = test predicates = diamonds
• EJEMPLO UN MAPA CUADRICULAR CON CALLES Y CADA INTERSECION ES DECIDIR UNA DIRECCION
• Even If I use structured programming (no GOTO) then if I have NOT 100% statement coverage then I have 100% test predicated.
  
  s1
  if x<10 then s2 s3
  x =5
  I have 100% statement coverage
  But NOT 100% decision coverage, false case is MISSING!
• Statement Coverage Do Not Imply Decision Coverage!
• Decision Coverage satisfies Statement but Statement not necessarily satisfies Decision!
  So Software must cover 100% Decision Coverage

4. Decision-Condition Coverage

• Develop test such that each condition in a decision takes on all possible outcomes and each decision takes on all possible outcomes
• This is like Decision++ (the second part of the definition, is Decision Coverage)
  
  if x<10 or y>50 and z!=0 or flag= T and status = NIL
  then S1
  else S2
  
  2 test to statement coverage
  2 test to decision coverage

  But that not enough for Decision-Condition Coverage.
  We need to open the test predicate and look inside: there are 5 conditions!

  For each condition we need to test their TRUE and FALSE cases

  We need 2 cases. All false and All True.

5. Multiple Condition

• Develop test to execute all combinations of conditions within a decision.
  This is the most powefull.

6. Example, Test Binary Search Algorithm)

(1) start <-1; (2) end <-num; (3) found <- false; (4) while starts <= end and not found //(C1) and (C2)
(5) middle <-(start = end)/2 (6) if key > table[middle] //(C3)
(7) then start <- middle +1 (8) else if key = table[middle] //(c4)
(9) then found <-T (10) LOC <- middle; (11) else end <- middle -1

We have 4 conditions, and we have 11 statements (each row). We have three decision points and we have one case with multiple (2) conditions.

if4
T
F

if6
T
F

if8
T
F

For multiple-condition coverage C1 y C2 make combinations of T y F

For conditions C3 y C4 simply try one T and one F of each one

Example of Execution

10 20 30 40 50 60 70 Key=55

1
2
3
4 with T, T
5
6 T
7

4 done before T, T
5
6 F

8 with F

11

4 con T, T
5
6 T
7

4 con F, T

• Multiple-condition Coverage: 100% NO
• Decision-condition Coverage: 100% NO
• Decision Coverage: NO
• Statement coverage: NO

Now execute this:

10 20 30 40 50 60 70 Key = 40

1
2
3
4 with T, T
5
6 with F

8 with T

9
10

4 with T,F

Coverage is cumulative

4. Multiple-condition Coverage NOT 100% (75%)
3. Decision-condition Coverage 100%
2. Decision Coverage 100%
1. Statement Coverage 100%