testing-methods

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Testing methods

What are the different methods of testing?

Testing takes place during the testing stage of the program development life cycle, once the program has been written and compiled
- Syntax errors are usually detected during compilation
- Testing focuses on checking for logic errors, unexpected behaviour, and operational integrity
- A detailed test plan, outlining test cases and expected results, should be created during the analysis stage

Sample test plan

Scenario: A program accepts a user’s age between 0 and 120 inclusive

Test No.	Description	Input	Expected output	Type of test data
1	Valid age within accepted range	25	“Age accepted”	Normal
2	Input is not a number	“twenty”	“Invalid input: enter a number”	Abnormal
3	Age above the maximum allowed	130	“Age out of range”	Extreme
4	Age exactly at the upper boundary	120	“Age accepted”	Boundary
5	Age exactly at the lower boundary	0	“Age accepted”	Boundary
6	Age just below lower boundary	-1	“Age out of range”	Extreme
7	Blank input	(blank)	“Please enter your age”	Abnormal

Common methods of testing

Testing method	Description
Dry run	Manually trace through the code (e.g. on paper) to predict output and track variables
Walkthrough	Step-by-step review of the code with others to identify issues early
White-box testing	Tests the internal logic and code structure; the tester knows how the program works
Black-box testing	Tests the inputs and expected outputs without knowing the internal workings
Integration testing	Checks that different modules or components work correctly together
Alpha testing	Performed in-house by the developers during early testing
Beta testing	Carried out by external users in real-world environments
Acceptance testing	Final check to ensure the program meets the original client requirements
Stub testing	Uses temporary modules (stubs) to simulate missing components during early testing

Choosing suitable test data

What is suitable test data?

Suitable test data is specially chosen to test the functionality of a program or design
Developers or test-users would pick a selection of test data from the following categories
- Normal
- Abnormal
- Extreme
- Boundary
The results would be compared to the expected results to check if the algorithm/program works as intended
The results would be stored in the test plan
Each category is explained within the context of a simple pseudocode program below

Pseudocode
`DECLARE name : STRING DECLARE age : INTEGER OUTPUT "What is your name? " INPUT name OUTPUT "How old are you? " INPUT age IF age >= 12 AND age <= 18 THEN OUTPUT "Welcome, " + name + "! Your age is accepted." ELSE OUTPUT "Sorry, " + name + ". Your age is not accepted." ENDIF`

Pseudocode

DECLARE name : STRING
DECLARE age : INTEGER OUTPUT "What is your name? "
INPUT name OUTPUT "How old are you? "
INPUT age IF age >= 12 AND age <= 18 THEN OUTPUT "Welcome, " + name + "! Your age is accepted."
ELSE OUTPUT "Sorry, " + name + ". Your age is not accepted."
ENDIF

Normal data

Normal test data is data that should be accepted in the program
An example would be a user entering their age as 16 into the age field of the program

Abnormal data

Abnormal test data is data that is the wrong data type
An example would be a user entering their age as “F” into the age field of the program

Extreme data

Extreme test data is the maximum and minimum values of normal data that are accepted by the system
An example would be a user entering their age as 18 or 12 into the age field of the program

Boundary data

Boundary test data is similar to extreme data except that the values on either side of the maximum and minimum values are tested
The largest and smallest unacceptable values
An example would be a user entering their age as 11 or 19 into the age field of the program

Selecting suitable test data

Type of Test	Input	Expected Output
Normal	14	Accepted
Normal	16	Accepted
Extreme	12	Accepted
Extreme	18	Accepted
Abnormal	H	Rejected
Abnormal	@	Rejected
Boundary	11	Rejected
Boundary	19	Rejected

Computer-science_A-level_Cie

testing-methods

Testing methods

What are the different methods of testing?

Sample test plan

Common methods of testing

Choosing suitable test data

What is suitable test data?

Normal data

Abnormal data

Extreme data

Boundary data

Selecting suitable test data

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