Software testing

Software Testing
R.BoomaDevi Asst.Prof & Head
Department of IT
E.M.G.Yadava Women’s College
Madurai -14

Software Testing
• Testing is the process of evaluating a system or its
component(s) with the intent to find whether it
satisfies the specified requirements or not.
• Testing is executing a system in order to identify
any gaps, errors, or missing requirements in
contrary to the actual requirements.
• This tutorial will give you a basic understanding
on software testing, its types, methods, levels,
and other related terminologies.

Learn Software Testing
In the IT industry, large companies have a team with
responsibilities to evaluate the developed software in context of the
given requirements. Moreover, developers also conduct testing
which is called Unit Testing. In most cases, the following
professionals are involved in testing a system within their respective
capacities −
Software Tester
Software Developer
Project Lead/Manager
End User
Different companies have different designations for people
who test the software on the basis of their experience and knowledge
such as Software Tester, Software Quality Assurance Engineer, QA
Analyst, etc.

Applications of Software Testing
Cost Effective Development - Early testing saves both time and cost in
many aspects, however reducing the cost without testing may result in
improper design of a software application rendering the product useless.
Product Improvement - During the SDLC phases, testing is never a
time-consuming process. However diagnosing and fixing the errors
identified during proper testing is a time-consuming but productive
activity.
Test Automation - Test Automation reduces the testing time, but it is not
possible to start test automation at any time during software
development. Test automaton should be started when the software has
been manually tested and is stable to some extent. Moreover, test
automation can never be used if requirements keep changing.

Quality Check - Software testing helps
in determining following set of
properties of any software such as
Functionality
Reliability
Usability
Efficiency
Maintainability
Portability

Verification & Validation
These two terms are very confusing for most people, who use them interchangeably. The
following table highlights the differences between verification and validation.
Sr.No. Verification Validation
1 Verification addresses the concern: "Are
you building it right?"
Validation addresses the concern: "Are
you building the right thing?"
2 Ensures that the software system meets
all the functionality.
Ensures that the functionalities meet the
intended behavior.
3 Verification takes place first and includes
the checking for documentation, code,
etc.
Validation occurs after verification and
mainly involves the checking of the overall
product.
4 Done by developers. Done by testers.
5 It has static activities, as it includes
collecting reviews, walkthroughs, and
inspections to verify a software.
It has dynamic activities, as it includes
executing the software against the
requirements.
6 It is an objective process and no subjective
decision should be needed to verify a
software.
It is a subjective process and involves
subjective decisions on how well a
software works.

Testing, Quality Assurance, and Quality Control
Quality Assurance Quality Control Testing
QA includes activities that
ensure the implementation of
processes, procedures and
standards in context to
verification of developed
software and intended
requirements.
It includes activities that
ensure the verification of a
developed software with
respect to documented (or
not in some cases)
requirements.
It includes activities that
ensure the identification of
bugs/error/defects in a
software.
Focuses on processes and
procedures rather than
conducting actual testing on
the system.
Focuses on actual testing by
executing the software with
an aim to identify bug/defect
through implementation of
procedures and process.
Focuses on actual testing.
Process-oriented activities. Product-oriented activities. Product-oriented activities.
Preventive activities. It is a corrective process. It is a preventive process.
It is a subset of Software Test
Life Cycle (STLC).
QC can be considered as the
subset of Quality Assurance.
Testing is the subset of
Quality Control.

Testing and Debugging
Testing − It involves identifying bug/error/defect in
a software without correcting it. Normally professionals
with a quality assurance background are involved in bugs
identification. Testing is performed in the testing phase.
Debugging − It involves identifying, isolating, and
fixing the problems/bugs. Developers who code the
software conduct debugging upon encountering an error
in the code. Debugging is a part of White Box Testing or
Unit Testing. Debugging can be performed in the
development phase while conducting Unit Testing or in
phases while fixing the reported bugs.

Manual Testing
Following are the testing techniques that are
performed manually during the test life cycle:
Acceptance Testing
White Box Testing
Black Box Testing
Unit Testing
System Testing
Integration Testing

Black-box testing
It is carried out to test functionality of the program. It is also
called ‘Behavioral’ testing. The tester in this case, has a set of
input values and respective desired results. On providing input, if
the output matches with the desired results, the program is
tested ‘ok’, and problematic otherwise.
In this testing method, the design and structure of the code are
not known to the tester, and testing engineers and end users
conduct this test on the software.
Black-box testing techniques:

Black-box testing techniques:
Equivalence class - The input is divided into similar classes. If one
element of a class passes the test, it is assumed that all the class is
passed.
Boundary values - The input is divided into higher and lower end
values. If these values pass the test, it is assumed that all values in
between may pass too.
Cause-effect graphing - In both previous methods, only one input
value at a time is tested. Cause (input) – Effect (output) is a testing
technique where combinations of input values are tested in a systematic
way.
Pair-wise Testing - The behavior of software depends on multiple
parameters. In pairwise testing, the multiple parameters are tested pair-
wise for their different values.
State-based testing - The system changes state on provision of input.
These systems are tested based on their states and input.

White-box testing
It is conducted to test program and its implementation, in
order to improve code efficiency or structure. It is also known as
‘Structural’ testing.
In this testing method, the design and structure of the
code are known to the tester. Programmers of the code conduct
this test on the code.

Control-flow testing - The purpose of the
control-flow testing to set up test cases which
covers all statements and branch conditions.
The branch conditions are tested for both
being true and false, so that all statements
can be covered.
Data-flow testing - This testing technique
emphasis to cover all the data variables
included in the program. It tests where the
variables were declared and defined and
where they were used or changed.

Testing Levels
Testing itself may be defined at various levels of
SDLC. The testing process runs parallel to software
development. Before jumping on the next stage, a stage
is tested, validated and verified.
Testing separately is done just to make sure that
there are no hidden bugs or issues left in the software.
Software is tested on various levels -
Unit Testing
While coding, the programmer performs some tests on
that unit of program to know if it is error free. Testing is
performed under white-box testing approach. Unit testing
helps developers decide that individual units of the
program are working as per requirement and are error
free.

Integration Testing
Even if the units of software are working fine
individually, there is a need to find out if the
units if integrated together would also work
without errors. For example, argument passing
and data updating etc.

System Testing
The software is compiled as product and then it is tested as a whole.
This can be accomplished using one or more of the following tests:
Functionality testing - Tests all functionalities of the software
against the requirement.
Performance testing - This test proves how efficient the software is.
It tests the effectiveness and average time taken by the software to do
desired task. Performance testing is done by means of load testing and
stress testing where the software is put under high user and data load
under various environment conditions.
Security & Portability - These tests are done when the software is
meant to work on various platforms and accessed by number of
persons.

Acceptance Testing
When the software is ready to hand over to the customer it
has to go through last phase of testing where it is tested for user-
interaction and response. This is important because even if the
software matches all user requirements and if user does not like the
way it appears or works, it may be rejected.
Alpha testing - The team of developer themselves perform alpha
testing by using the system as if it is being used in work environment.
They try to find out how user would react to some action in software
and how the system should respond to inputs.
Beta testing - After the software is tested internally, it is handed over
to the users to use it under their production environment only for
testing purpose. This is not as yet the delivered product. Developers
expect that users at this stage will bring minute problems, which were
skipped to attend.

Regression Testing
Whenever a software product is updated
with new code, feature or functionality, it is
tested thoroughly to detect if there is any
negative impact of the added code. This is
known as regression testing.

Before Testing
Testing starts with test cases generation. Following documents are needed for reference
–
SRS document - Functional Requirements document
Test Policy document - This describes how far testing should take place before
releasing the product.
Test Strategy document - This mentions detail aspects of test team, responsibility
matrix and rights/responsibility of test manager and test engineer.
Traceability Matrix document - This is SDLC document, which is related to
requirement gathering process. As new requirements come, they are added to this
matrix. These matrices help testers know the source of requirement. They can be traced
forward and backward.
While Being Tested
The following documents may be required while testing is started and is being done:
Test Case document - This document contains list of tests required to be conducted. It
includes Unit test plan, Integration test plan, System test plan and Acceptance test plan.
Test description - This document is a detailed description of all test cases and
procedures to execute them.
Test case report - This document contains test case report as a result of the test.
Test logs - This document contains test logs for every test case report.

Software testing

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