Black-box-testing-techniqs-learnings.ppt

Random test

1. Random Testing

2. Outline
Who invented Random Testing ?
What is Random Testing ?
Why we use RT ?
How we use RT?
Main types of random testing
techniques
When we use RT ? 
Example
Where we use RT ?
Pros & Cons
RT Tools

4. Spesification-
Based
Techniques
Equivalance partitioning
Boundary value analysis
Decision table
Finite-state machine method
Testing from formal spesification
Random testing

5. Who invented
Random Testing
?
Random testing was mentioned first
time in the
The Art Of Software Testing
book of Glenford J. Myers in 1979

6. What is
Random Testing
?
All of the test inputs are generated
randomly (often using a tool).
t is a black box testing
İ

7. Why we use
RT ?
Random testing gives us an advantage
of easily estimating software reliability
from test outcomes. Test inputs are
randomly generated according to an
operational profile, and failure times are
recorded
The data obtained from random
testing can then be used to estimate
reliability. Other testing methods cannot
be used in this way to estimate software
reliability
Use of random test inputs may save
some of the time and effort that more
thoughtful test input selection methods
require.(domain is well-
structured)

8. How we use
RT?
Random Testing can be
summarized as a four-step procedure
1.The input domain is identified
2.Test inputs are selected independently
from the domain
3.The system under test is executed on
these inputs. This inputs constitude a
random test set.
4.The results are compared to the system
spesification. The test is a failure if any
input leads to incorrect results; otherwise
it is a success.

9. Main types of
random testing
techniques:
 
1.Random input data generation
2.Random sequence of data input
(sometimes called as stochastic
testing)
3.Random data selection from existing
database
It is possible to combine all the above
testing techniques.

10. When we use
RT ?
If we have a lot time and we want to
more reliability product.
If we dont have enought time to testing
product, but we must to test it.
We must consider the time needed to
write a random test generator vs the
time to write a set of directed tests(or
generators).
We doing random testing ensure that
our tests are sufficiently random, and
they cover specifications.

11. Example:
For example, if the valid input domain for a module
integers between 1 and 100, the tester using this
approach would randomly, or unsystematically, select
values from within that domain; for example, the
values 55,24,3 mighht be chosen. Given this
approach, some of the issues that remain open are
the following:
Are the three values adequate to show that the
module meets its specification when the tests are
run ? Should additional or fewer values be used to
make the most effective use of resources ?
Are there any input values, other than those selected,
more likely to reveal defects ? For example, should
positive integers at the beginning or end of the
domain be specifically selected as inputs ?
Should any values outside the valid domain be used
as test inputs? For example, should test data include
floating point values, negative values, or integer
values greater than 100 ?

12. Where we use
RT ?
Random Testing techniques are
applicable for any single project. They
will change from project to project.
 Usually required for the current project
testing techniques are described in the
test plan.
Different testing techniques can find
different types of defects.

13. What is
benefit ?
If the domain is well-structured,
automatic generation can be used,
allowing many more test cases to be run
than if tests are manually generated.
We can give surprisingly good result by
using correct alghorithm of course if the
domain is well-structured

14. RT has the
following
weakness
They are not realistic
Many of the tests are redundant and
unrealistic
You will spend more time analyzing
results
You cannot recreate the test if you do
not record what data was used for
testing
There is no measure of risk
Random testing is, of course, the most
used and least useful method

15. RT Tools
Jcheck
Randoop
Yeti-TEST
A Lightweight Tool

16. References
Software Testing and Quality
Assurance: Theory and Practice  By
Sagar Naik, Piyu Tripathy
Software Testing By Koirala Koirala,
Sheikh Sheikh
Practical Software Testing: A Process-
Oriented Approach  By Ilene Burnstein
http://c2.com/cgi/wiki?
RandomTesting
http://
extremesoftwaretesting.com/
Techniques/RandomTesting.html

17. Any Question ?