MBA management

Testing Concepts and Testing Tools topics:

Introduction


Development of complex software products includes several activities like understanding the customer requirements, design, coding and integration etc…These activities need to be coordinated and reviewed suitability to meet the desired requirements. Because of the complex nature of the process involved, unreliability of the designers and developers, any software development must be accompanied by Quality Assurance activities. Testing of the developed code or software is one such activity. It is not unusual that 40% of the effort in developing software is spent on Testing.

Software Testing is a process of verifying and validating software application to ensure that it meets the business, technical and functional requirements. A testing process requires accurate planning and preparation before doing the actual testing. According to Hertzel, “ Testing is the process of establishing confidence that a program does what it is supposed to do” and Mr. Glenford Myers define software testing, in this book, ‘ The Art of Software Testing ‘as” Testing is the process of executing a program with the intent of finding errors”.

Now a day, Software testing became large and complex. The software deliverable includes program, document, data etc… so looking at Software testing as only testing of the Code has become irrelevant and has now a broader scope, which includes all the components. Testing holds several characteristic, such as

• Software testing starts with testing of requirements

• Software testing includes both static testing and dynamic testing

• Software testing aims at preventing the occurrence of failure

• Aims to fix the defects or faults at the early stages of the development life cycle and reduce the cost to fix the bugs

• Crates reusable test wares

Software testing , depending on the testing method employed, can be implemented at any time in the development process, however the most test effort is employed after the requirements have been defined and coding process has been completed.

Scope of Software Testing


A primary purpose for testing is to detect software failures so that defects may be uncovered and corrected. This is a non-trivial pursuit. Testing cannot establish that a product functions properly under all conditions but can only establish that it does not function properly under specific conditions. The scope of software testing often includes examination of code as well as execution of that code in various environments and conditions as well as examining the aspects of code: does it do what it is supposed to do and do what it needs to do. In the current culture of software development, a testing organization may be separate from the development team. There are various roles for testing team members. Information derived from software testing may be used to correct the process by which software is developed.

Defects and Failures


Not all software defects are caused are caused by coding errors. One common source of expensive defects is caused by requirement gaps, e.g., unrecognized requirements that result in errors of omission by the program designer. A common source of requirements that result in errors of omission by the program designer. A common source of requirements gaps is non-functional requirements such as testability scalability, maintainability, usability, performance, and security.

Software faults occur through the following processes. A programmer makes an error (mistake), which results in a defect (fault, bug) in the software source code. If this defect is executed, in certain situations the system will produce wrong results, causing a failure. Not all defects will necessarily result in failures. For example, defects in dead code will never result in failures. A defect can turn into a failure when the environment is changed. Examples of these changes in environment include the software being run on a new hardware platform, alterations in source data or interacting with different software. A single defect may result in a wide range of failure symptoms.

Compatibility


A frequent cause of software failure is compatibility with another application, a new operating system, or, increasingly, web browser version. In the case of lack of backward compatibility, this can occur because the programmers have only considered coding their programs for, or testing the software upon, “the latest version of” this- or- that operating system. The unintended consequence of this fact is that: their latest work might not be fully compatible with earlier mixtures of software/ hardware, or it might not be fully compatible with another important operating system. In any case, these differences, whatever they might be, may have resulted in software failures, as witnessed by some significant population of computer users.

Principles of Software testing


Software testing is a challenging task which requires creativity. Software testing can be effective and efficient by applying the established principles over the years. Some of them are:

• Testing must be done by a person or team external to the development team

• Assign responsibility to create Test case to personnel who are highly creative and have expertise in implementing those test cases

• The objective of the testing must be to identify more no. of errors

• Test for all invalid and unexpected input conditions as well as valid input conditions

• Identify and include expected results

• Don’t modify the software during testing

• Prepare test reports along with the test case

• Choose an appropriate testing method

The major purpose of software testing is to increase the software development team’s confidence that the software will function as per the requirements of the customer. It is the process of dynamic verification of software‘s functionality on selected test cases from infinite execution domain. Since the objective of the testing is to list out maximum number of errors, a successful test is the one which uncovers maximum number of errors.

A good software tester aims should be to design test cases that uncovers more number of errors with a minimum amount of effort and time.

Testing approaches


Static vs. Dynamic testing


There are many approaches to software testing. Reviews, walkthroughs or inspections are considered as static testing, whereas actually executing programmed code with a given set of test cases is referred to as dynamic testing. The former can be (and unfortunately in practice often is) omitted, whereas the latter takes place when programs begin to be used for the first time-Which is normally considered the beginning of the testing stage. This may actually begin before the program is 100% complete in order to test particular sections of code (modules or discrete functions). Typical techniques for this are using stubs/ drivers, or execution from a debugger environment. For example, Spreadsheet programs are, by their very nature, tested to a large extent” on the fly “during the build process as the result of some calculation or test manipulation is shown interactively immediately after ach formula is entered.

Software Verification and Validation


Software testing is used in association with verification and validation

• Verification: Have we built the software right (i.e., does it match the specification? It is process based.

• Validation: Have we built the right software (i.e., is this what the customer wants?) It is product based.

The terms verification and validation are commonly used interchangeably in the industry: it is also common to see these two terms incorrectly defined. According to the IEEE Standard Glossary of Software Engineering Terminology:

Verification is the process of evaluating a system or component during or at the end of the development process to determine whether it satisfies specified requirements.

The software Testing Team

Software testing can be done by software testers, Until the 1980s the team “software tester“ was used generally, but later it was also seen as a separate profession. Regarding the periods and the different goals in software testing, different roles have been established: manager, test lead, test designer, tester, automation developer, and test administrator.

Software Quality Assurance (SQA)


Though controversial, software testing may be viewed as an important part of the software quality assurance (SQA) process. In SQA, software process specialists and auditors take a broader view on software and its development. They examine and change the software engineering process itself to reduce the amount of faults that end up in the delivered software: the so-called defect rate.

What constitutes an “acceptable defect rate” depends on the nature of the software. For example, an arcade video game designed to simulate flying an airplane would presumably have a much higher tolerance for defects than mission critical software such as that used to control the functions of an airliner that rally is flying!

Although there are close links with SQA, testing departments often exist independently, and there may be no SQA function in some companies.

Software Testing is a task intended to detect in software by contrasting a computer program’s expected results with its actual results for a given set of inputs. By contrast, QA (Quality Assurance) is the implementation of policies and procedures intended to prevent defects from occurring in the first place.

Software Testing Methods


Software testing methods are traditionally divided into black box testing and white box testing. These two approaches are used to describe the point of view that a test engineer tasks when designing test cases.

Black Box Testing


Black box testing treats the software as a “black box” & without any knowledge of internal implementation. Black box testing methods include: equivalence partitioning, boundary value analysis, all-pairs testing, fuzz testing, model-based testing, traceability matrix, exploratory testing and specification-based testing.

Specification- Based Testing


Specification-based testing aims to test the functionality of software according to the applicable requirements. Thus, the tester inputs data into, and only sees the outputs from, the test object. This level of testing usually requires through test cases to be provided to the tester, who then can simply verify that for a given input, the output value ( or behavior), either “is” or is not” the same as the expected value specified in the test case. Specification-based testing is necessary, but it is insufficient to guard against certain risks.

Advantages and disadvantages

The black box tester has no “bonds” with the code, and a tester’s perception is very simple: a code must have bugs. Using the principle, “Ask and you shall receive,” black box testers find bugs where programmers don’t. But, on the other hand, black box testing has been said to be “like a walk in a dark labyrinth without a flashlight, “because the tester doesn’t know how the software being tested was actually constructed. That’s why there are situations when (1) a black box tester writes many test cases to check something that can be tested by only one test case, and/or (2) some parts of the black and are not tested at all.

Therefore, black box testing has the advantage of “an unaffiliated opinion,” on the one hand, and the disadvantage of “blind exploring,” on the other.

White Box Testing


White box testing, by contrast to black box testing, is when the tester has access to the internal data structures and algorithms including the code that implement these.

Types of white box testing

The following types of white box testing exist:

• API testing (application programming interface) - testing of the application using public and private APIs.

• Code coverage-creating tests to satisfy some criteria of code coverage. For example, the test designer can create tests to cause all statements in the program to be executed at least once.

• Fault injection methods.

• Mutation testing methods.

• Static testing- Whit box testing includes all static testing.

Code Completeness Evaluation


White box testing methods can also be used to evaluate the completeness of a test that was created with black box testing methods. This allows the software tam to examine parts of a system that are rarely tested and ensures that the most important function points have been tested.

Two common forms of code coverage are

• Function coverage, which reports on functions executed and statement coverage, which reports on the number of lines executed to complete the test.

• They both return coverage metric, measured as a percentage.

Grey Box Testing


Grey box testing involves having access to internal data structures and algorithms for purposes of designing the test cases, but testing at the user, or black-box level. Manipulating input data and formatting output do not qualify as grey box, because the input and output are clearly outside of the “black-box” that we are calling the system under test. This distinction is particularly important when conducting integration testing between two modules of code written by two different developers, where only the interfaces are ‘exposed for test. However, modifying a data repository does qualify as grey box, as the user would not normally be able to change the data outside of the system under test. Grey box testing may also include reverse engineering to determine, for instance, boundary values or error messages.

Acceptance Testing


Acceptance testing can mean one of two things:

1. A smoke test is used as an acceptance test prior to introducing a build to the main testing process.

2. Acceptance testing performed by the customer is known as user acceptance testing (UAT).

Regression Testing


Regression testing is any type of software testing that seeks to uncover software regressions. Such regression occurs whenever software functionality that was previously working correctly stops working as intended. Typically regression testing includes re-running previously working correctly stops working as intended. Typically regressions occur as an unintended consequence of program changes. Common methods of regression testing include re-running previously run tests and checking whether previously fixed faults have re- emerged.

Non Functional Software Testing


Special methods exist to test non-functional aspects of software.

• Performance testing checks to see if the software can handle large quantities of data or users. This is generally referred to as software scalability. This activity of Non Functional Software Testing is often times referred to as Load Testing.

• Stability testing checks to see if the software can continuously function well in or above an acceptable period. This activity of Non Functional Software Testing is often times referred to as enduration test.

• Usability testing is needed to check if the user interface is easy to use and understand.

• Security testing is essential for software which processes confidential data and to prevent system intrusion by hackers.

• Internationalization and localization is needed to test these aspects of software, for which a pseudo localization method can be used.

In contrast to functional testing, which establishes the correct operation of the software (correct in that it matches the expected behavior defined in the design requirements), non-functional testing verifies that the software functions properly even when it receives invalid or unexpected inputs. Software fault injection, in the form of fizzing is an example of non-functional testing. Non-functional testing, especially for software, is designed to establish whether the device under test can tolerate invalid or unexpected inputs, thereby establishing the robustness of input validation routines as well as error-handling routines. Various commercial non-functional testing tools are linked from the Software fault injection page; there are also numerous open-source and free software tools available that perform non-functional testing.

Testing process


A common practice of software testing is performed by an independent group of testers after the functionality is developed before it is shipped to the customer. This practice often results in the testing phase being used as project buffer to compensate for project delays, thereby compromising the time devoted to testing. Another practice is to start software testing at the same moment the project starts and it is a continuous process until the project finishes.

In counterpoint, some emerging software disciplines such as extreme programming and the agile software development movement, adhere to a “test- driven software development “model. In this process, unit tests are written first, by the software engineers (often with pair programming in the extreme programming methodology). Of course these tests fail initially: as they are expected to. Then as code is written it passes incrementally larger portions of the test suites. The test suites are continuously updated as new failure conditions and corner cases are discovered, and they are integrated with any regression tests that are development .Unit tests are maintained along with the rest of the software source code and generally integrated into the build process( with inherently interactive tests being relegated to a partially manual build acceptance process).

Testing can be done on the following levels:

• Unit testing tests the minimal software component, or module. Each unit (basic component) of the software is tested to verify that the detailed design for the unit has been correctly implemented. In an object-oriented environment, this is usually at the class level, and the minimal unit tests include the constructors and destructors.

• Integration testing exposes defects in the interfaces and interaction between integrated components (modules). Progressively larger groups of tested software components corresponding to elements of the architectural design are integrated and tested until the software works as a system.

• System testing tests a completely integrated system to verify that it meets its requirements.

• System integration testing verifies that a system is integrated to any external or third party systems defined in the system requirements.

Before shipping the final version of software, alpha and beta testing are often done additionally:

• Alpha testing is simulated or actual operational testing by potential users/ customers or an independent test team at the developers’ site. Alpha testing is often employed for off-the-shelf software as a form of internal acceptance testing, before the software goes to beta testing.

• Beta testing comes after alpha testing. Versions of the software, known as beta versions, are released to a limited audience outside of the programming team. The software is released to groups of people so that further testing can ensure the product has few faults or bugs. Sometimes, beta versions are made available to the open public to increase the feedback field to a maximal number of future users.

Finally, acceptance testing can be conducted by the end-user, customer, or client to validate whether or not to accept the product. Acceptance testing may be performed as part of the hand- off process between any two phases of development.

After modifying software, either for a change in functionality or to fix defects, a regression test re-runs previously passing tests on the modified software to ensure that the modifications haven’t unintentionally caused a regression of previous functionality. Regression testing can be performed at any or all of the above test levels. These regression tests are often automated.

More specific forms of regression testing are known as sanity testing, when quickly checking for bizarre behavior, and smoke testing when testing for basic functionality.

Benchmarks may be employed during regression testing to ensure that the performance of the newly modified software will be at least as acceptable as the earlier version or, in the case of code optimization, that some real improvement has been accomplished.

Measuring Software Testing


Usually, quality is constrained to such topics as correctness, completeness, security, but can also include more technical requirements as described under the ISO standard ISO 9126, such as capability, reliability, efficiency, portability, maintainability, compatibility, and usability.

There are number of common software measures, often called “metrics”, which are used to measure the stat of the software or the adequacy of the testing.

Testing Artifacts

Software testing process can produce several artifacts.

Test case

Test case in software engineering normally consists of an unique identifier, requirement references from a design specification, preconditions, events, a series of steps ( also known as actions) to follow, input, output, expected result, and actual result. Clinically defined a test case is an input and an expected result, and actual result. Clinically defined a test case is an input and an expected result. This can be as pragmatic as “for condition x your derived result is y”, whereas other test cases described in more detail the input scenario and what results might be expected. It can occasionally be a series of steps (but often steps are contained in a separate test procedure that can be exercised against multiple test cases, as a matter of economy) but with one expected outcome. The optional fields are a test case ID, test step or order of execution number, related requirement(s), depth, test category, author, and check boxes for whether the test is automatable and has been automated. Larger test cases may also contain prerequisite states or steps, and descriptions. A test case should also contain a place for actual result. These steps can be stored in a word processor document, spreadsheet, database, or other common repository. In a database system, you may also be able to see past test results and who generated the results and the system configuration used to generate those results. These past results would usually be stored in a separate table.

Test script

The test script is the combination of a test case, test procedure, and data. Initially the term was derived from the product of work created by automated regression test tools. Today, test scripts can be manual, automated, or a combination of both.

Test data

The most common test manually or in automation is retesting and regression testing. In most cases, multiple sets of values or data are used to test the same functionality of a particular feature. All the test values and changeable environmental components are collected in separate files and stored as test data. It is also useful to provide this data to the client and with the product or a project.

Test suite

The most common tam for a collection of test cases is a test suite. The test suit often also contains more detailed instructions or goals for each collection of test cases. It definitely contains a section where the tester identifies the system configuration used during testing. A group of test cases may also contain prerequisite states or steps, and descriptions of the following tests.

Test plan

A test specification is called a test plan. The developers are well aware what test plans will be executed and this information is made available to the developers. This makes the developers more cautious when developing their cod. This ensures that the developer’s code is not passed through any surprise test case or test plans.

Test harness

The software, tools, samples of data input and output, and configurations are all referred to collectively as a test harness.

Traceability matrix

A traceability matrix is a table that correlates requirements or design documents to test documents. It is used to change tests when the source documents are changed, or to verify that the test results are correct.

A Sample Testing Cycle

Although variations exist between organizations, there is a typical cycle for testing.

Requirements analysis: Testing should begin in the requirements phase of the software development life cycle. During the design phase, testers would with developers in determining what aspects of a design are testable and with parameters those work.

Test planning: Test strategy, test plan, test plan, test bed creation. A lot of activities will be carried out during testing, so that a plan is needed.

Test development: Test procedures. Test scenarios, test cases, test datasets, test scripts to use in testing software.

Test execution: Testers execute the software based on the plans and tests and report any errors found to the development team.

Test reporting: Once testing is completed, testers generate metrics and make final reports on their test effort and whether or not the software tested is react for release.

Test result analysis: Or Defect Analysis, is done by the development tam usually along with the client, in order to decide what defects should be treated, fixed, rejected (i.e., found software working properly) or deferred to be dealt with at a later time.

Retesting of resolved defects: Once a defect has been dealt with by the development team, it is retested by the testing team.

Regression testing: It is common to have a small test program built of a subset of tests, for each integration of new, modified or fixed software, in order to ensure that the latest delivery has not ruined anything, and that the software product as a whole is still working correctly.

Test closure: Once the test meets the exit criteria, the activities such as capturing the key outputs, lessons learned, results, logs, documents related to the project are archived and used as a reference for future projects.

Certifications


Several certification programs exist to support the professional aspirations of software testers and quality assurance specialists. No certification currently offered actually requires the application to demonstrate the ability to test software. No certification is based on a widely accepted body of knowledge. This has led some to declare that the testing field is not ready for certification. Certification itself cannot measure an individual’s productivity, their skill, or practical knowledge, and cannot guarantee their competence, or professionalism as a tester.

Software testing certification types

Certification can be grouped into: exam –based and education-based.

Exam–based certifications: For these there is the ned to pass an exam, which can also be learned by self-study : e.g., for ISTQB or QAI.

Education-based certifications: Education based software testing certifications are instructor- led sessions, where each course has to be passed, e.g., IIST (Internal Institute for Software Testing).

Testing certifications

• CATe offered by the Internal Institute for Software Testing

• Certified Software Tester (CSTE) offered by the Quality Assurance Institute (QAI)

• Certified Software Test Professional (CSTP) offered by the International Institute for Software Testing

• CSTP (TM) (Australian Version ) offered by K.J. Ross & Associates

• ISEM offered by the Information Systems Examinations Boards

• ISTQB Certified Tester, Advanced Level (CTAL) offered by the International Software Testing Qualification Board

• TMPF TMap R Next Foundation offered by the Examination Institute for Information Science

Quality assurance certifications

• CSQE offered by the American Society for Quality (ASQ)
• CSQA offered by the Quality Assurance Institute (QUI)
• CQIA offered by the American Society for Quality (ASQ)
• CMSQ offered by the Quality Assurance Institute (QAI)

Software testing life cycle


Software testing life cycle identifies what test activities to carry out and when (what is the best time) to accomplish those test activities. Even though testing differs between organizations, there is a testing life cycle.

Software Testing Life Cycle consists of six (generic) phases:

• Test planning,
• Test Analysis,
• Test Design, Construction and verification,
• Testing Cycles,
• Final Testing and Implementation and
• Post Implementation.

Software testing has its own life cycle that intersects with every stage of the SDLC. The basic requirements in Software testing life cycle is to control/deal with software testing-Manual, Automated and Performance.

Test Planning


This is the phase where project Manager has to decide what things need to be tested, do I have the appropriate budget etc. Naturally proper planning at this stage would greatly reduce the risk of low quality software. This planning will be an ongoing process with no end.

Activities at this stage would include preparation of high level test plan (according to EEE test plan template The Software Test Plan (STP) is designed to prescribe the scope, approach, resources, and schedule of all testing activities. The plan must identify the items to be tested, the features to be tested, the types of testing to be performed, the personnel responsible for testing, the resources and schedule required to complete testing, and the risks associated with the plan). Almost all of the activities done during this stage are included in this software test plan and revolve around a test plan.

Test Analysis


Once test plan is mad and decided upon, next step is to delve little more into the project and decide what types of testing should be carried out at different stages of SDLC, do we need or plan to automat, if yes then when the appropriate time to automate is, what type of specific documentation I need for testing.

Proper and regular meetings should be held between testing teams, project managers, and development teams. Business Analysts to check the progress of things which will give fair idea of the movement of the project and ensure the completeness of the test plan created in the planning phase, which will further help in enhancing the right testing strategy crated earlier. We will start crating test case formats and test cases itself. In this stage we need to develop Functional validation matrix based on Business Requirements to ensure that all system requirements are covered by one or more test cases, identify which test cases to automate, begin review of documentation, i.e., Functional Design, Business Requirements, Product Specifications, Product Externals etc. We also have to define areas for Stress and performance testing.

Test Design


Test plans and cases which were developed in the analysis phase are revised. Functional validation matrix is also revised and finalized. In this stage risk assessment criteria is developed. If you have thought of automation then you have to select which test cases to automate and begin writing scripts for them. Testing is revised (if necessary) & finalized and test environment is prepared.

Construction and Verification


In this phase we have to complete all the test plans, complete the scripting of the automated test cases, Stress and performance testing plans needs to be completed. We have to support the development team in their unit testing phase. And obviously bug reporting would be done as when the bugs are found. Integration tests are performed and errors (if any) are reported.

Testing Cycles


In this phase we have to complete testing cycles until test cases are executed without errors or a predefined condition is reached. Run test cases -> report Bugs ->revise test cases (if needed) ->add new test cases (if needed) -> bug fixing -> retesting (test cycle 2, test cycle 3…).

Final Testing and Implementation


In this we have to execute remaining stress and performance test cases, documentation for testing is completed/ updated, provide and complete different metrics for testing. Acceptance, load and recovery testing will also be conducted and the application needs to be verified under production conditions.

Post Implementation


In this phase, the testing process is evaluated and lessons learnt from that testing process are documented. Line of attack to prevent similar problems in future projects is identified. Create plans to improve the processes. The recording of new errors and enhancements is an ongoing process. Cleaning up of test environment is done and test machines are restored to base lines in this stage.

Software Testing Life Cycle

Phase   Activities             Outcome
Planning   Create high level test plan   Test plan, Refined Specification
Analysis   Create detailed test plan   Revised Test plan, Functional validation matrix, test cases
Design  

Test cases are revised;

Select which test cases to automate
  Revised test cases, test data sets, sets, risk assessment sheet
Construction   Scripting of test cases to automate   Test procedures/ Scripts, Drivers, test results, Bug reports.
Testing cycles   Complete testing cycles   Test results, Bug Reports
Final testing   Execute remaining stress and performance tests, complete documentation   Test results and different metrics on test efforts
Post implementation   Evaluate testing processes   Plan for improvement of testing process


Testing tools


With the trend of automating the task, there are many software tools available, which may be used to help the testing process. Such tools help to achieve accurate results in reduced time and effort. The availability and capability of testing tools often enhance the level of testability of software.

Program testing and fault detection can be aided significantly by testing tools and debuggers. Testing/debug tools include features such as:

• Program monitors, permitting full or partial monitoring of program code including:

- Instruction Set Similar, permitting step-by-step execution and conditional breakpoint at source level or in machine code

- Program animation, permitting step-by-step execution and conditional breakpoint at source level or in machine code

- code coverage reports

• Formatted dump or Symbolic debugging, tools allowing inspection of program variables on error or at chosen points

• Benchmarks, allowing run-time performance comparisons to be made

• Performance analysis, or profiling tools that can help to highlight hot spots and resource usage

Some of these features may be incorporated into an integrated development environment (IDE).

Conclusion


Software testing is the process of verifying and validating software application or program to achieve the business and technical requirements. One of the major objectives of the testing is to generate good test cases that have a high probability of finding more number of errors with less time and effort. Software testing demonstrates that the software appears to be working as stated in the specifications.
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Review Questions
  • 1. What are the principles of software testing?
  • 2. Explain in detail about testing approaches?
  • 3. What is SQA. Explain?
  • 4. Explain briefly about software testing methods?
  • 5. What is regression testing? When we will use this testing?
  • 6. Explain in detail about software testing life cycle?
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