Session 4-Test 2 practical.pptx, Essays (university) of Law

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Session 4

Testing basics

Objectives

• Applying tests in SDLC

• Understanding testing

• Understanding and being able to use black box testing

• (^) Writing test cases
• (^) Evaluating actual test results

• Understanding and being able to use white box testing

• (^) Writing test cases
• (^) Evaluating actual test results

• Acceptance Testing

Defining a test case

• By IEEE documentation standard #829-

– A set of test inputs, execution conditions, and

expected results developed for a particular

objective, such as to exercise a particular program

path or to verify compliance with a specific

requirement.

– Documentation specifying inputs, predicted

results, and a set of execution conditions for a test

item.

Test approaches

• One of the important phases software

development life cycle is testing

• The aim of testing is

– To investigate whether the system meets its given

specifications

– To explore defects before the system is delivered

• Two main types of testing include

– Black box testing

– White box testing

Black box testing example

• Specification

– Write a program called TripleNumber to triple any

input integer

• The only testing you can do if you do not have

access to the code is to try some inputs

• Unfortunately, this may not find a fault in the

program

– All it proves is that it works correctly for these

values , at this time.

Specifying the inputs for test cases

• To improve the chance of finding defects, the

input for testing should cover

– Normal cases (should be general enough)

– Extreme/boundary/Validating cases

White box testing

• It is also called as structural testing

• Tests are derived from the knowledge of the

program code

• This knowledge allows the testing of the

various paths that the program execution can

take

Test Input Output

White box testing example

• Now we have access to the code

– In this case we can see that there is selection

controlled by whether the input is >= 1 or not

White box testing - test cases example

Case id Input Expected output Actual output Status 1 10 You are 10 year(s) old 2 -1 Invalid input 3 1 You are 1 year(s) old 4 twenty Invalid input Case 1 to cover the “if” path of the code. Case 2 to cover the “else” path of the code. Case 3 is the extreme/boundary case. Case 4 is the data validating case.

Calculator example

• Specification

– Write a program which takes a number, then

either invert it or take its square

– E.g., if the number is 5 it produces either 1/

(invert) or 25 (square)

Black box testing – invert test cases

Input Expected output Actual output Status 10 Invert result is 0.1 Invert result is 0.1 passed -10 Invert result is -0.1 Invert result is -0.1 passed 0 Cannot invert 0 Cannot invert 0 passed Twenty Invalid input Cannot invert 0 failed 9999999999999999 Invalid input Wrong unexpected result failed

Black box testing – square test cases Input Expected output Actual output Status 10 Square result is 100 Square result is 100 passed -10 Square result is 100 Square result is 100 passed 0 Square result is 0 Square result is 0 passed Twenty Invalid input Square result is 0 failed 9999999999999999 Invalid input Wrong unexpected output failed

Error handling in Calculator

• The black box testing also revealed that there

is some error handling in the code

• It recognized two standard errors for invert

– Trying to invert 0

– Trying to invert a text input

• It recognized one standard error for square

– Trying to square a text input

White box testing of the calculator