A Practical Learning Guide to Software Testing by Olusola Samuel Fatiregun

Author:Olusola Samuel Fatiregun [Fatiregun, Olusola Samuel]
Language: eng
Format: epub
Publisher: UNKNOWN
Published: 2017-02-07T08:00:00+00:00

White Box, Glass box or Structure-based Techniques

 It is structure-based because the internal structure of software (i.e. code) is used to design Test Cases

 The code must be visible to testers

 So understanding of internals (code) is required

 Specification is still used to determine expected results, as for black-box

Code  Pseudo code at foundation level

o Limited language

o Simple structure

o Helps to create all the main control structures

 Non executable

o At the start of the code

o No action

o Declarative and preparative

 Executable

o Instructs the computer to take action

o starts with BEGIN……ends with END when combined with Non Executable

Code Structure 1. Sequence

o Statement executed one after the other as they appear on page

2. Selection

o Computer decides if a condition is true or false (Boolean) then takes a route based on the outcome

o Involves decisions

3. Iterative

o Repeat exercising of a chunk of code

o Number of iteration depends on the value of a condition

Sequence Example:

1. Read X

2. Read Y

3. Z = X*Y

Note: We have 3 executable statements here; 1 is done before 2, then 3. No Non executable statement. Absence of BEGIN and END is common practice in ISEB so be aware! Selection

Example:

1. IF K < 5 /*condition*/

2. THEN

3. X = X+1 /*condition in 1 is TRUE*/

4. ELSE

5. X=X-1 /*condition in 1 is FALSE*/

6. ENDIF /*Terminates the IF THEN ELSE*/

Iteration  Also known as Loops

 Two types:

1. DO WHILE or WHILE DO 2. REPEAT UNTIL

 Involve at least a condition

 Also involve at least a decision

 DO WHILE : Condition at the beginning

 REPEAT UNTIL: Condition at the end

DO WHILE LOOP

Example:

Figure 25: DO WHILE LOOP Example Hands-on Practice Exercise 8

1. How many iteration(s) will be achieved in this loop (Figure 25)?

2. How can you alter the code to achieve no iteration?

REPEAT UNTIL LOOP Example:

Figure 26: REPEAT UNTIL LOOP Example Hands-on Practice Exercise 9

1. How many iterations will be achieved in this loop?

2. How can you alter the code to achieve no iteration?

Flow Chart Structures

Figure 27: Flow Chart Structures

Control Flow Graph  Method of representing decision points and the flow of control within a code  Only shows decisions

 Concentrate on parts of the code (statements) affecting the flow of control  Contains

o Nodes : decision points, END WHILE or ENDIF

o Edges: line connecting the nodes

Figure 28: Control Flow Graph

Control Flow Subgraphs

Figure 29: Control Flow Subgraphs

Statement Testing and Coverage  Testing aimed at exercising programming statements

 Every executable statement is tested by 100% statement coverage  Do not count non executable statements

 Converting code to flow charts is a good way of knowing where the executable

statements are

 Executable statements are represented by diamonds or rectangles on a flow chart  We can also use Conventional Control Flow Diagrams to determine Statement

Coverage – this called a Hybrid Flow Diagram

 Exclude non executable statements that precede BEGIN

 Ignore blank lines

 Weak /inadequate measure of test

Decision Testing and Coverage  Decisions in a program are tested

 A decision is tested when a condition associated with it is true and false  100% decision coverage is measured by counting

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