1.basics of software testing

BASICS OF SOFTWARE
TESTING
Chapter 1

Topics to be covered
1. Humans and errors,
2. Testing and Debugging,
3. Software Quality- Correctness Reliability
4. Fundamentals of Test Process,
5. General Principles of Testing ,
6. Test Metrics
January 12, 20181.Basics of Software Testing/D.S.Jagli
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Errors, faults, failures
Humans and errors,
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1.Basics of Software Testing/D.S.Jagli
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Errors
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 Errors are a part of our daily life.
 Humans make errors in their thoughts, actions,
and in the products that might result from their
actions.
 Errors occur wherever humans are involved in
taking actions and making decisions.
These fundamental facts of human existence make testing
an essential activity.
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Errors: Examples
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Error, Faults, Failures
 Error (erroneous action) human action that produces an
incorrect result. [Ieee 610.12]
 Fault is also called A defect or internal error.
 An example might be wrongly programmed or forgotten code
in the application
 Failure is A non fulfillment of A given requirement; A
discrepancy between the actual result or behavior (identified
while executing the test) and the expected result or behavior
(defined in the specifications or requirements).
 Examples of failures are products that are too hard to use or
too slow, but still fulfill the functional requirements.
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Error, Faults, Failures
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Differences
2.Testing and Debugging,
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Testing And Debugging
 Testing is the process of determining if a
program has any errors.
 When testing reveals an error, the
process used to determine the cause of
this error and to remove it, is known as
debugging.
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1. The goal of testing is to detect
errors
2. It is initiated with known
conditions.
3. The o/p can be anticipated.
4. It is a conformation.
5. It find out reason for failure.
6. Design knowledge is not required.
7. It is performed by person who
doesn't belong to development
team.
8. Test design and execution are done
automatically.
9. It should follow certain constraints
or rules.
10. It is necessary to have proper
planning
1. To detect errors and correct them.
2. It is initiated with un known conditions.
3. The o/p can not be anticipated.
4. It is a reduction process.
5. it is the programmer’s justification.
6. Detailed Design knowledge is required.
7. It is performed by person who belong
to development team.
8. Design and execution can’t be done
automatically.
9. It shoud have experimentations and
guesses.
10. It is not required proper planning.
Testing debugging
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A Test/Debug Cycle
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It s very important in testing
Software Quality,
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Software Quality
 We all want high quality software.
 There exist several measures of software quality.
 Attributes can be divided into static and dynamic
quality attributes.
 Static attributes refer to the actual code and
documentation.
 Dynamic attributes refer to behavior of the
application while in use.
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Software Quality Attributes
 Static quality attributes: structured, maintainable,
testable code as well as the availability of correct and
complete documentation.
 Dynamic quality attributes: software reliability,
correctness, completeness, consistency, usability, and
performance
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Software Quality (Contd.)
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Completeness refers to the availability of all features listed in
the requirements, or in the user manual.
An incomplete software is one that does not fully implement all
features required.
Consistency refers to adherence to a common set of conventions
and assumptions.
For example, all buttons in the user interface might follow a
common color coding convention.
An example of inconsistency would be when a database
application displays the date of birth of a person in the database.
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Software Quality
 Usability refers to the ease with which an application can be
used. This is an area in itself and there exist techniques for
usability testing.
 Psychology plays an important role in the design of
techniques for usability testing.
 Performance refers to the time the application takes to
perform a requested task. It is considered as a non-functional
requirement. It is specified in terms such as ``This task must
be performed at the rate of X units of activity in one second
on a machine running at speed Y, having Z gigabytes of
memory."
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Software Reliability: Two Definitions
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Software reliability [ANSI/IEEE Std 729-1983]:
is the probability of failure free operation of
software over a given time interval and under
given conditions.
Software reliability is the probability of failure
free operation of software in its intended
environment.
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Software Reliability
In the standard, the quality characteristic is split into maturity,
fault tolerance, and recoverability.
1. Fault tolerance is the capability of the software product to
maintain a specified level of performance, or to recover from
faults in cases of software faults, or of infringement of its
specified interface.
2. Maturity means how often a failure of the software occurs
as a result of defects in the software.
3. Recoverability is the capability of the software product to
reestablish a specified level of performance and recover the
data directly affected in the case of a failure.
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Correctness vs. Reliability
 Though correctness of a program is desirable, it is almost
never the objective of testing.
 To establish correctness via testing would imply testing a
program on all elements in the input domain.
 In most cases that are encountered in practice, this is
impossible to accomplish.
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Thus correctness is established via
mathematical proofs of programs.
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Correctness and Testing
 While correctness attempts to establish that the
program is error free, testing attempts to find if there
are any errors in it.
 Thus completeness of testing does not necessarily
demonstrate that a program is error free.
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Testing, debugging, and the error removal processes
together increase our confidence in the correct
functioning of the program under test.
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Fundamental of Test Process
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Fundamental Of Test Process
 The description of tasks in the process models is not
sufficient to perform structured tests in software
projects.
 In addition to the embedding of testing in the whole
development process, a more detailed process for the
testing tasks is needed.
 The development task testing must be split into
subtasks
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Fundamental Test Process
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General Principles of Testing
 Principle 1: Testing shows the presence of defects,
not their absence.
 Principle 2: Exhaustive testing is not possible.
 Principle 3: Testing activities should start as early as
possible.
 Principle 4: Defects tend to cluster together.
 Principle 5: The pesticide paradox.
 Principle 6: Test is context dependent.
 Principle 7: The fallacy of assuming that no failures
means a useful system
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Test Metrics
 Test Metrics:
1. Organizational
2. Project
3. Process
4. Product
 Static
 Dynamic
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Types Of Testing
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C1: Source of test generation.
C2: Lifecycle phase in which testing takes place
C3: Goal of a specific testing activity
C4: Characteristics of the artifact under test
One possible classification is based on the following four
classifiers:
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C1: Source of test generation
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1.Fundamentals of Testing/D.S.Jagli01/12/18 27

C2: Lifecycle phase in which testing takes
place
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C3: Goal of specific testing activity
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C4: Artifact under test
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1.basics of software testing

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1.basics of software testing