There are different levels during the process of
Testing. In this chapter a brief description is provided about these levels.
Levels of testing include the different
methodologies that can be used while conducting Software Testing. Following are
the main levels of Software Testing:
·
Functional Testing.
·
Non-Functional Testing.
Functional Testing
This is a type of black box testing that is
based on the specifications of the software that is to be tested. The
application is tested by providing input and then the results are examined that
need to conform to the functionality it was intended for. Functional Testing of
the software is conducted on a complete, integrated system to evaluate the
system's compliance with its specified requirements.
There are five steps that are involved when
testing an application for functionality.
Steps
|
Description
|
I
|
The determination of
the functionality that the intended application is meant to perform.
|
II
|
The creation of test
data based on the specifications of the application.
|
III
|
The output based on
the test data and the specifications of the application.
|
IV
|
The writing of Test
Scenarios and the execution of test cases.
|
V
|
The comparison of
actual and expected results based on the executed test cases.
|
An effective testing practice will see the above
steps applied to the testing policies of every organization and hence it will
make sure that the organization maintains the strictest of standards when it
comes to software quality.
Unit Testing
This type of testing is performed by the
developers before the setup is handed over to the testing team to formally
execute the test cases. Unit testing is performed by the respective developers
on the individual units of source code assigned areas. The developers use test
data that is separate from the test data of the quality assurance team.
The goal of unit testing is to isolate each part
of the program and show that individual parts are correct in terms of
requirements and functionality.
LIMITATIONS OF UNIT
TESTING
Testing cannot catch each and every bug in an
application. It is impossible to evaluate every execution path in every
software application. The same is the case with unit testing.
There is a limit to the number of scenarios and
test data that the developer can use to verify the source code. So after he has
exhausted all options there is no choice but to stop unit testing and merge the
code segment with other units.
Integration Testing
The testing of combined parts of an application
to determine if they function correctly together is Integration testing. There
are two methods of doing Integration Testing Bottom-up Integration testing and
Top Down Integration testing.
S.N.
|
Integration Testing
Method
|
1
|
Bottom-up integration
This testing begins with unit testing, followed by tests of progressively
higher-level combinations of units called modules or builds.
|
2
|
Top-Down integration
This testing, the highest-level modules are tested first and progressively
lower-level modules are tested after that.
|
In a comprehensive software development
environment, bottom-up testing is usually done first, followed by top-down
testing. The process concludes with multiple tests of the complete application,
preferably in scenarios designed to mimic those it will encounter in customers'
computers, systems and network.
System Testing
This is the next level in the testing and tests
the system as a whole. Once all the components are integrated, the application
as a whole is tested rigorously to see that it meets Quality Standards. This
type of testing is performed by a specialized testing team.
System testing is so important because of the
following reasons:
·
System Testing is the
first step in the Software Development Life Cycle, where the application is
tested as a whole.
·
The application is
tested thoroughly to verify that it meets the functional and technical
specifications.
·
The application is
tested in an environment which is very close to the production environment
where the application will be deployed.
·
System Testing enables
us to test, verify and validate both the business requirements as well as the
Applications Architecture.
Regression Testing
Whenever a change in a software application is
made it is quite possible that other areas within the application have been
affected by this change. To verify that a fixed bug hasn't resulted in another
functionality or business rule violation is Regression testing. The intent of
Regression testing is to ensure that a change, such as a bug fix did not result
in another fault being uncovered in the application.
Regression testing is so important because of
the following reasons:
·
Minimize the gaps in
testing when an application with changes made has to be tested.
·
Testing the new changes
to verify that the change made did not affect any other area of the
application.
·
Mitigates Risks when
regression testing is performed on the application.
·
Test coverage is
increased without compromising timelines.
·
Increase speed to market
the product.
Acceptance Testing
This is arguably the most importance type of
testing as it is conducted by the Quality Assurance Team who will gauge whether
the application meets the intended specifications and satisfies the client.s
requirements. The QA team will have a set of pre written scenarios and Test
Cases that will be used to test the application.
More ideas will be shared about the application
and more tests can be performed on it to gauge its accuracy and the reasons why
the project was initiated. Acceptance tests are not only intended to point out
simple spelling mistakes, cosmetic errors or Interface gaps, but also to point
out any bugs in the application that will result in system crashers or major
errors in the application.
By performing acceptance tests on an application
the testing team will deduce how the application will perform in production.
There are also legal and contractual requirements for acceptance of the system.
ALPHA TESTING
This test is the first stage of testing and will
be performed amongst the teams (developer and QA teams). Unit testing,
integration testing and system testing when combined are known as alpha
testing. During this phase, the following will be tested in the application:
·
Spelling Mistakes
·
Broken Links
·
Cloudy Directions
·
The Application will be
tested on machines with the lowest specification to test loading times and any
latency problems.
BETA TESTING
This test is performed after Alpha testing has
been successfully performed. In beta testing a sample of the intended audience
tests the application. Beta testing is also known as pre-release testing. Beta
test versions of software are ideally distributed to a wide audience on the
Web, partly to give the program a "real-world" test and partly to
provide a preview of the next release. In this phase the audience will be
testing the following:
·
Users will install, run
the application and send their feedback to the project team.
·
Typographical errors,
confusing application flow, and even crashes.
·
Getting the feedback,
the project team can fix the problems before releasing the software to the
actual users.
·
The more issues you fix
that solve real user problems, the higher the quality of your application will
be.
·
Having a higher-quality
application when you release to the general public will increase customer
satisfaction.
Non-Functional Testing
This section is based upon the testing of the
application from its non-functional attributes. Non-functional testing of
Software involves testing the Software from the requirements which are non
functional in nature related but important a well such as performance,
security, user interface etc.
Some of the important and commonly used
non-functional testing types are mentioned as follows:
Performance Testing
It is mostly used to identify any bottlenecks or
performance issues rather than finding the bugs in software. There are
different causes which contribute in lowering the performance of software:
·
Network delay.
·
Client side processing.
·
Database transaction
processing.
·
Load balancing between
servers.
·
Data rendering.
Performance testing is considered as one of the
important and mandatory testing type in terms of following aspects:
·
Speed (i.e. Response
Time, data rendering and accessing)
·
Capacity
·
Stability
·
Scalability
It can be either qualitative or quantitative testing activity and
can be divided into different sub types such as Load testing and Stress testing.
LOAD TESTING
A process of testing the behavior of the
Software by applying maximum load in terms of Software accessing and
manipulating large input data. It can be done at both normal and peak load
conditions. This type of testing identifies the maximum capacity of Software
and its behavior at peak time.
Most of the time, Load testing is performed with
the help of automated tools such as Load Runner, AppLoader, IBM Rational
Performance Tester, Apache JMeter, Silk Performer, Visual Studio Load Test etc.
Virtual users (VUsers) are defined in the
automated testing tool and the script is executed to verify the Load testing
for the Software. The quantity of users can be increased or decreased
concurrently or incrementally based upon the requirements.
STRESS TESTING
This testing type includes the testing of
Software behavior under abnormal conditions. Taking away the resources,
applying load beyond the actual load limit is Stress testing.
The main intent is to test the Software by
applying the load to the system and taking over the resources used by the
Software to identify the breaking point. This testing can be performed by
testing different scenarios such as:
·
Shutdown or restart of
Network ports randomly.
·
Turning the database on
or off.
·
Running different
processes that consume resources such as CPU, Memory, server etc.
Usability Testing
This section includes different concepts and
definitions of Usability testing from Software point of view. It is a black box
technique and is used to identify any error(s) and improvements in the Software
by observing the users through their usage and operation.
According to Nielsen, Usability can be defined
in terms of five factors i.e. Efficiency of use, Learn-ability, Memor-ability,
Errors/safety, satisfaction. According to him the usability of the product will
be good and the system is usable if it possesses the above factors.
Nigel Bevan and Macleod considered that
Usability is the quality requirement which can be measured as the outcome of
interactions with a computer system. This requirement can be fulfilled and the
end user will be satisfied if the intended goals are achieved effectively with
the use of proper resources.
Molich in 2000 stated that user friendly system
should fulfill the following five goals i.e. Easy to Learn, Easy to Remember,
Efficient to Use, Satisfactory to Use and Easy to Understand.
In addition to different definitions of
usability, there are some standards and quality models and methods which define
the usability in the form of attributes and sub attributes such as ISO-9126,
ISO-9241-11, ISO-13407 and IEEE std.610.12 etc.
UI VS USABILITY TESTING
UI testing involves the testing of Graphical
User Interface of the Software. This testing ensures that the GUI should be
according to requirements in terms of color, alignment, size and other
properties.
On the other hand Usability testing ensures that
a good and user friendly GUI is designed and is easy to use for the end user.
UI testing can be considered as a sub part of Usability testing.
Security Testing
Security testing involves the testing of
Software in order to identify any flaws ad gaps from security and vulnerability
point of view. Following are the main aspects which Security testing should
ensure:
·
Confidentiality.
·
Integrity.
·
Authentication.
·
Availability.
·
Authorization.
·
Non-repudiation.
·
Software is secure
against known and unknown vulnerabilities.
·
Software data is secure.
·
Software is according to
all security regulations.
·
Input checking and
validation.
·
SQL insertion attacks.
·
Injection flaws.
·
Session management
issues.
·
Cross-site scripting
attacks.
·
Buffer overflows
vulnerabilities.
·
Directory traversal
attacks.
Portability Testing
Portability testing includes the testing of
Software with intend that it should be re-useable and can be moved from another
Software as well. Following are the strategies that can be used for Portability
testing.
·
Transferred installed
Software from one computer to another.
·
Building executable
(.exe) to run the Software on different platforms.
Portability testing can be considered as one of
the sub parts of System testing, as this testing type includes the overall
testing of Software with respect to its usage over different environments.
Computer Hardware, Operating Systems and Browsers are the major focus of Portability
testing. Following are some pre-conditions for Portability testing:
·
Software should be
designed and coded, keeping in mind Portability Requirements.
·
Unit testing has been
performed on the associated components.
·
Integration testing has
been performed.
·
Test environment has
been established.
