Thinking in software testing

Software Testing Part IThinking in Software Testing

Saroj Sangphongamphai, August [email protected]

Sincerely grateful to all teachers, professors, books,

websites, and others.

Think Big, Set the High Goal

Software development life cycle Analysis and design Planing Implementation Testing Deployment

What is software testing?1.Testing is the process of demonstrating that errors are not present.

2.The purpose of testing is to show that a program performs its intended functions correctly.

3.Testing is the process of establishing confidence that a program does what it is supposed to do.

What is software testing?

Testing is the process of executing a program with the intent of finding

errors.

Terms for software failuresDefect

FaultProblem

ErrorIncident

Anomaly

VarianceFailureInconsistencyFeatureBugEtc.

Software bug: a formal definition(1 of 5)

The software does not do something that the product specification says it should

do.


The software does something that the product specification says it should not

do.


The software does something that the product specification does not mention.


The software does not do something that the product specification does not

mention but should.


The software is difficult to understand, hard to use, slow, or in the software

tester’s eyes will be viewed by the end user as just plain not right.

Software bug: a formal definition1.The software does not do something that the product specification says

it should do.2.The software does something that the product specification says it

should not do.3.The software does something that the product specification does not

mention.4.The software does not do something that the product specification does

not mention but should.5.The software is difficult to understand, hard to use, slow, or in the

software tester’s eyes will be viewed by the end user as just plain not right.

Insights from a Venn Diagram

Insights from a Venn Diagram

Why do bug occurs?

The cost of bugs

To find bugs To find them as early as possible And to make sure they get fixed

The goal of a software tester

The challenge of software testing

Exhaustive testing is impractical.

Exhaustive testing is impracticalA simple function adds two 32 bit numbers and returns a result.

Assumption: we can execute 1,000 test cases per second

How long will it take to exhaustively test this function?

(Signed range 32 bits integer is -2,147,483,648 to 2,147,483,647 and unsigned: 0 to 4,294,967,295)

Exhaustive testing is impracticalA simple function adds two 32 bit numbers and returns a result.

Assumption: we can execute 1,000 test cases per second

How long will it take to exhaustively test this function?

Answer: 585 million years2 (32+32) /1000/60/60/24/365 = 584,942,417 years.

(Signed range 32 bits integer is -2,147,483,648 to 2,147,483,647 and unsigned: 0 to 4,294,967,295)

Optimal amount of testing

The psychology of software testing

A successful test case is one that detects an undiscovered error.



Testing can only show the presence of errors, not their absence.


A necessary part of a test case is a definition of the expected output or

result.

The difference between testing and debugging

Testing = Find Bug

Debugging = Remove Bug

Quality is free

Early testing, more prevention than detection

Quality is not equal to test

If it is not built right in the first place, then it is never going to be right.

Quality is not equal to test

Quality is achieved by putting development and testing into a blender and mixing them until one is indistinguishable from the other.

Primary metric

Cycle time

Reference

Question & Answer

Next

Software Testing Part IITesting Techniques