What is Iterative model- advantages, disadvantages and when to use it?

jamanbabu

Fiverr

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I am a professional tester with 1.5 year of experience in this field.I have experience in application and website testing on several devices and offer a thorough and rigorous test of your website or application.

An iterative life cycle model does not attempt to start with a full specification of requirements. Instead, development begins by specifying and implementing just part of the software, which can then be reviewed in order to identify further requirements. This process is then repeated, producing a new version of the software for each cycle of the model.

In the diagram above when we work iteratively we create rough product or product piece in one iteration, then review it and improve it in next iteration and so on until it’s finished. As shown in the image above, in the first iteration the whole painting is sketched roughly, then in the second iteration colors are filled and in the third iteration finishing is done. Hence, in iterative model the whole product is developed step by step.

Diagram of Iterative model:

Advantages of Iterative model:

• In iterative model we can only create a high-level design of the application before we actually begin to build the product and define the design solution for the entire product. Later on we can design and built a skeleton version of that, and then evolved the design based on what had been built.
• In iterative model we are building and improving the product step by step. Hence we can track the defects at early stages. This avoids the downward flow of the defects.
• In iterative model we can get the reliable user feedback. When presenting sketches and blueprints of the product to users for their feedback, we are effectively asking them to imagine how the product will work.
• In iterative model less time is spent on documenting and more time is given for designing.

 Disadvantages of Iterative model: 

• Each phase of an iteration is rigid with no overlaps
• Costly system architecture or design issues may arise because not all requirements are gathered up front for the entire lifecycle

When to use iterative model:

• Requirements of the complete system are clearly defined and understood.
• When the project is big.
• Major requirements must be defined; however, some details can evolve with time.

What is Agile model – advantages, disadvantages and when to use it?

Agile development model is also a type of Incremental model. Software is developed in incremental, rapid cycles. This results in small incremental releases with each release building on previous functionality. Each release is thoroughly tested to ensure software quality is maintained. It is used for time critical applications.  Extreme Programming (XP) is currently one of the most well known agile development life cycle model.

Diagram of Agile model:

Advantages of Agile model:

• Customer satisfaction by rapid, continuous delivery of useful software.
• People and interactions are emphasized rather than process and tools. Customers, developers and testers constantly interact with each other.
• Working software is delivered frequently (weeks rather than months).
• Face-to-face conversation is the best form of communication.
• Close, daily cooperation between business people and developers.
• Continuous attention to technical excellence and good design.
• Regular adaptation to changing circumstances.
• Even late changes in requirements are welcomed

Disadvantages of Agile model:

• In case of some software deliverables, especially the large ones, it is difficult to assess the effort required at the beginning of the software development life cycle.
• There is lack of emphasis on necessary designing and documentation.
• The project can easily get taken off track if the customer representative is not clear what final outcome that they want.
• Only senior programmers are capable of taking the kind of decisions required during the development process. Hence it has no place for newbie programmers, unless combined with experienced resources.

When to use Agile model:

• When new changes are needed to be implemented. The freedom agile gives to change is very important. New changes can be implemented at very little cost because of the frequency of new increments that are produced.
• To implement a new feature the developers need to lose only the work of a few days, or even only hours, to roll back and implement it.
• Unlike the waterfall model in agile model very limited planning is required to get started with the project. Agile assumes that the end users’ needs are ever changing in a dynamic business and IT world. Changes can be discussed and features can be newly effected or removed based on feedback. This effectively gives the customer the finished system they want or need.
• Both system developers and stakeholders alike, find they also get more freedom of time and options than if the software was developed in a more rigid sequential way. Having options gives them the ability to leave important decisions until more or better data or even entire hosting programs are available; meaning the project can continue to move forward without fear of reaching a sudden standstill.

You can refer to our introduction to Agile Methodology if you would like to understand Agile better.

What is RAD model- advantages, disadvantages and when to use it?

RAD model is Rapid Application Development model. It is a type of incremental model. In RAD model the components or functions are developed in parallel as if they were mini projects. The developments are time boxed, delivered and then assembled into a working prototype.  This can quickly give the customer something to see and use and to provide feedback regarding the delivery and their requirements.

Diagram of RAD-Model:

The phases in the rapid application development (RAD) model are:

Business modeling: The information flow is identified between various business functions.
Data modeling: Information gathered from business modeling is used to define data objects that are needed for the business.
Process modeling: Data objects defined in data modeling are converted to achieve the business information flow to achieve some specific business objective. Description are identified and created for CRUD of data objects.
Application generation: Automated tools are used to convert process models into code and the actual system.
Testing and turnover: Test new components and all the interfaces.

Advantages of the RAD model:

• Reduced development time.
• Increases reusability of components
• Quick initial reviews occur
• Encourages customer feedback
• Integration from very beginning solves a lot of integration issues.

Disadvantages of RAD model:

• Depends on strong team and individual performances for identifying business requirements.
• Only system that can be modularized can be built using RAD
• Requires highly skilled developers/designers.
• High dependency on modeling skills
• Inapplicable to cheaper projects as cost of modeling and automated code generation is very high.

 When to use RAD model:

• RAD should be used when there is a need to create a system that can be modularized in 2-3 months of time.
• It should be used if there’s high availability of designers for modeling and the budget is high enough to afford their cost along with the cost of automated code generating tools.
• RAD SDLC model should be chosen only if resources with high business knowledge are available and there is a need to produce the system in a short span of time (2-3 months).

What is Incremental model- advantages, disadvantages and when to use it?

In incremental model the whole requirement is divided into various builds. Multiple development cycles take place here, making the life cycle a “multi-waterfall” cycle.  Cycles are divided up into smaller, more easily managed modules. Incremental model is a type of software development model like V-model, Agile model etc.

In this model, each module passes through the requirements, design, implementation and testing phases. A working version of software is produced during the first module, so you have working software early on during the software life cycle. Each subsequent release of the module adds function to the previous release. The process continues till the complete system is achieved.

In the diagram above when we work incrementally we are adding piece by piece but expect that each piece is fully finished. Thus keep on adding the pieces until it’s complete. As in the image above a person has thought of the application. Then he started building it and in the first iteration the first module of the application or product is totally ready and can be demoed to the customers. Likewise in the second iteration the other module is ready and integrated with the first module. Similarly, in the third iteration the whole product is ready and integrated. Hence, the product got ready step by step.

Diagram of Incremental model:

Advantages of Incremental model:

• Generates working software quickly and early during the software life cycle.
• This model is more flexible – less costly to change scope and requirements.
• It is easier to test and debug during a smaller iteration.
• In this model customer can respond to each built.
• Lowers initial delivery cost.
• Easier to manage risk because risky pieces are identified and handled during it’d iteration.

Disadvantages of Incremental model:

• Needs good planning and design.
• Needs a clear and complete definition of the whole system before it can be broken down and built incrementally.
• Total cost is higher than waterfall.

When to use the Incremental model:

• This model can be used when the requirements of the complete system are clearly defined and understood.
• Major requirements must be defined; however, some details can evolve with time.
• There is a need to get a product to the market early.
• A new technology is being used
• Resources with needed skill set are not available
• There are some high risk features and goals.

What is V-model- advantages, disadvantages and when to use it?

V- model means Verification and Validation model. Just like the waterfall model, the V-Shaped life cycle is a sequential path of execution of processes. Each phase must be completed before the next phase begins. V-Model is one of the many software development models.Testing of the product is planned in parallel with a corresponding phase of development in V-model.

Diagram of V-model:

The various phases of the V-model are as follows:

Requirements like BRS and SRS begin the life cycle model just like the waterfall model. But, in this model before development is started, a system test plan is created.  The test plan focuses on meeting the functionality specified in the requirements gathering.

The high-level design (HLD) phase focuses on system architecture and design. It provide overview of solution, platform, system, product and service/process. An integration test plan is created in this phase as well in order to test the pieces of the software systems ability to work together.

The low-level design (LLD) phase is where the actual software components are designed. It defines the actual logic for each and every component of the system. Class diagram with all the methods and relation between classes comes under LLD. Component tests are created in this phase as well.

The implementation phase is, again, where all coding takes place. Once coding is complete, the path of execution continues up the right side of the V where the test plans developed earlier are now put to use.

Coding: This is at the bottom of the V-Shape model. Module design is converted into code by developers. Unit Testing is performed by the developers on the code written by them.

Advantages of V-model:

• Simple and easy to use.
• Testing activities like planning, test designing happens well before coding. This saves a lot of time. Hence higher chance of success over the waterfall model.
• Proactive defect tracking – that is defects are found at early stage.
• Avoids the downward flow of the defects.
• Works well for small projects where requirements are easily understood.

Disadvantages of V-model:

• Very rigid and least flexible.
• Software is developed during the implementation phase, so no early prototypes of the software are produced.
• If any changes happen in midway, then the test documents along with requirement documents has to be updated.

When to use the V-model:

• The V-shaped model should be used for small to medium sized projects where requirements are clearly defined and fixed.
• The V-Shaped model should be chosen when ample technical resources are available with needed technical expertise.

High confidence of customer is required for choosing the V-Shaped model approach. Since, no prototypes are produced, there is a very high risk involved in meeting customer expectations.

What is Waterfall model- advantages, disadvantages and when to use it?

The Waterfall Model was first Process Model to be introduced. It is also referred to as a linear-sequential life cycle model.  It is very simple to understand and use.  In a waterfall model, each phase must be completed fully before the next phase can begin. This type of software development model is basically used for the for the project which is small and there are no uncertain requirements. At the end of each phase, a review takes place to determine if the project is on the right path and whether or not to continue or discard the project. In this model software testing starts only after the development is complete. In waterfall model phases do not overlap.

Diagram of Waterfall-model:

Advantages of waterfall model:

• This model is simple and easy to understand and use.
• It is easy to manage due to the rigidity of the model – each phase has specific deliverables and a review process.
• In this model phases are processed and completed one at a time. Phases do not overlap.
• Waterfall model works well for smaller projects where requirements are very well understood.

 Disadvantages of waterfall model:

• Once an application is in the testing stage, it is very difficult to go back and change something that was not well-thought out in the concept stage.
• No working software is produced until late during the life cycle.
• High amounts of risk and uncertainty.
• Not a good model for complex and object-oriented projects.
• Poor model for long and ongoing projects.
• Not suitable for the projects where requirements are at a moderate to high risk of changing.

When to use the waterfall model:

• This model is used only when the requirements are very well known, clear and fixed.
• Product definition is stable.
• Technology is understood.
• There are no ambiguous requirements
• Ample resources with required expertise are available freely
• The project is short.

Very less customer interaction is involved during the development of the product. Once the product is ready then only it can be demoed to the end users. Once the product is developed and if any failure occurs then the cost of fixing such issues are very high, because we need to update everywhere from document till the logic.

What are the Software Development Models?

The software development models are the various processes or methodologies that are being selected for the development of the project depending on the project’s aims and goals. There are many development life cycle models that have been developed in order to achieve different required objectives. The models specify the various stages of the process and the order in which they are carried out.

The selection of model has very high impact on the testing that is carried out. It will define the what, where and when of our planned testing, influence regression testing and largely determines which test techniques to use.

There are various Software development models or methodologies. They are as follows:

1. Waterfall model
2. V model
3. Incremental model
4. RAD model
5. Agile model
6. Iterative model
7. Spiral model
8. Prototype model

Choosing right model for developing of the software product or application is very important. Based on the model the development and testing processes are carried out.
Different companies based on the software application or product, they select the type of development model whichever suits to their application. But these days in market the ‘Agile Methodology‘ is the most used model. ‘Waterfall Model‘ is the very old model. In ‘Waterfall Model’ testing starts only after the development is completed. Because of which there are many defects and failures which are reported at the end. So,the cost of fixing these issues are high. Hence, these days people are preferring ‘Agile Model’. In ‘Agile Model’ after every sprint there is a demo-able feature to the customer. Hence customer can see the features whether they are satisfying their need or not.
‘V-model‘ is also used by many of the companies in their product. ‘V-model’ is nothing but ‘Verification’ and ‘Validation’ model. In ‘V-model’ the developer’s life cycle and tester’s life cycle are mapped to each other. In this model testing is done side by side of the development.
Likewise ‘Incremental model’, ‘RAD model’, ‘Iterative model’ and ‘Spiral model’ are also used based on the requirement of the customer and need of the product.
Start learning about the models with Waterfall model and its advantages and disadvantages.

 

What are the Software Development Life Cycle (SDLC) phases?

There are various software development approaches defined and designed which are used/employed during development process of software, these approaches are also referred as “Software Development Process Models” (e.g. Waterfall model, incremental model, V-model, iterative model, RAD model, Agile model, Spiral model, Prototype model etc.). Each process model follows a particular life cycle in order to ensure success in process of software development.
Software life cycle models describe phases of the software cycle and the order in which those phases are executed. Each phase produces deliverables required by the next phase in the life cycle. Requirements are translated into design. Code is produced according to the design which is called development phase. After coding and development the testing verifies the deliverable of the implementation phase against requirements. The testing team follows Software Testing Life Cycle (STLC) which is similar to the development cycle followed by the development team.
There are following six phases in every Software development life cycle model:

1. Requirement gathering and analysis
2. Design
3. Implementation or coding
4. Testing
5. Deployment
6. Maintenance

1) Requirement gathering and analysis:  Business requirements are gathered in this phase. This phase is the main focus of the project managers and stake holders. Meetings with managers, stake holders and users are held in order to determine the requirements like; Who is going to use the system? How will they use the system?  What data should be input into the system?  What data should be output by the system?  These are general questions that get answered during a requirements gathering phase. After requirement gathering these requirements are analyzed for their validity and the possibility of incorporating the requirements in the system to be development is also studied.
Finally, a Requirement Specification document is created which serves the purpose of guideline for the next phase of the model. The testing team follows the Software Testing Life Cycle and starts the Test Planning phase after the requirements analysis is completed.
2)  Design:  In this phase the system and software design is prepared from the requirement specifications which were studied in the first phase. System Design helps in specifying hardware and system requirements and also helps in defining overall system architecture. The system design specifications serve as input for the next phase of the model.
In this phase the testers comes up with the Test strategy, where they mention what to test, how to test.
3)  Implementation / Coding:  On receiving system design documents, the work is divided in modules/units and actual coding is started. Since, in this phase the code is produced so it is the main focus for the developer. This is the longest phase of the software development life cycle.
4)  Testing:  After the code is developed it is tested against the requirements to make sure that the product is actually solving the needs addressed and gathered during the requirements phase. During this phase all types of functional testing like unit testing, integration testing, system testing, acceptance testing are done as well as non-functional testing are also done.
5)  Deployment: After successful testing the product is delivered / deployed to the customer for their use.
As soon as the product is given to the customers they will first do the beta testing. If any changes are required or if any bugs are caught, then they will report it to the engineering team. Once those changes are made or the bugs are fixed then the final deployment will happen.
6) Maintenance: Once when the customers starts using the developed system then the actual problems comes up and needs to be solved from time to time. This process where the care is taken for the developed product is known as maintenance.

What is Capability Maturity Model (CMM)? What are CMM Levels?

Capability Maturity Model is a bench-mark for measuring the maturity of an organization’s software process. It is a methodology used to develop and refine an organization’s software development process. CMM can be used to assess an organization against a scale of five process maturity levels based on certain Key Process Areas (KPA). It describes the maturity of the company based upon the project the company is dealing with and the clients. Each level ranks the organization according to its standardization of processes in the subject area being assessed.

A maturity model provides:

• A place to start
• The benefit of a community’s prior experiences
• A common language and a shared vision
• A framework for prioritizing actions
• A way to define what improvement means for your organization

In CMMI models with a staged representation, there are five maturity levels designated by the numbers 1 through 5 as shown below:

1. Initial
2. Managed
3. Defined
4. Quantitatively Managed
5. Optimizing

Maturity levels consist of a predefined set of process areas. The maturity levels are measured by the achievement of the specific and generic goals that apply to each predefined set of process areas. The following sections describe the characteristics of each maturity level in detail.

Maturity Level 1 – Initial: Company has no standard process for software development. Nor does it have a project-tracking system that enables developers to predict costs or finish dates with any accuracy.

In detail we can describe it as given below:

• At maturity level 1, processes are usually ad hoc and chaotic.
• The organization usually does not provide a stable environment. Success in these organizations depends on the competence and heroics of the people in the organization and not on the use of proven processes.
• Maturity level 1 organizations often produce products and services that work but company has no standard process for software development. Nor does it have a project-tracking system that enables developers to predict costs or finish dates with any accuracy.
• Maturity level 1 organizations are characterized by a tendency to over commit, abandon processes in the time of crisis, and not be able to repeat their past successes.

Maturity Level 2 – Managed: Company has installed basic software management processes and controls. But there is no consistency or coordination among different groups.

In detail we can describe it as given below:

• At maturity level 2, an organization has achieved all the specific and generic goals of the maturity level 2 process areas. In other words, the projects of the organization have ensured that requirements are managed and that processes are planned, performed, measured, and controlled.
• The process discipline reflected by maturity level 2 helps to ensure that existing practices are retained during times of stress. When these practices are in place, projects are performed and managed according to their documented plans.
• At maturity level 2, requirements, processes, work products, and services are managed. The status of the work products and the delivery of services are visible to management at defined points.
• Commitments are established among relevant stakeholders and are revised as needed. Work products are reviewed with stakeholders and are controlled.
• The work products and services satisfy their specified requirements, standards, and objectives.

Maturity Level 3 – Defined: Company has pulled together a standard set of processes and controls for the entire organization so that developers can move between projects more easily and customers can begin to get consistency from different groups.

In detail we can describe it as given below:

• At maturity level 3, an organization has achieved all the specific and generic goals.
• At maturity level 3, processes are well characterized and understood, and are described in standards, procedures, tools, and methods.
• A critical distinction between maturity level 2 and maturity level 3 is the scope of standards, process descriptions, and procedures. At maturity level 2, the standards, process descriptions, and procedures may be quite different in each specific instance of the process (for example, on a particular project). At maturity level 3, the standards, process descriptions, and procedures for a project are tailored from the organization’s set of standard processes to suit a particular project or organizational unit.
• The organization’s set of standard processes includes the processes addressed at maturity level 2 and maturity level 3. As a result, the processes that are performed across the organization are consistent except for the differences allowed by the tailoring guidelines.
• Another critical distinction is that at maturity level 3, processes are typically described in more detail and more rigorously than at maturity level 2.
• At maturity level 3, processes are managed more proactively using an understanding of the interrelationships of the process activities and detailed measures of the process, its work products, and its services.

Maturity Level 4 – Quantitatively Managed: In addition to implementing standard processes, company has installed systems to measure the quality of those processes across all projects.

In detail we can describe it as given below:

• At maturity level 4, an organization has achieved all the specific goals of the process areas assigned to maturity levels 2, 3, and 4 and the generic goals assigned to maturity levels 2 and 3.
• At maturity level 4 Sub-processes are selected that significantly contribute to overall process performance. These selected sub-processes are controlled using statistical and other quantitative techniques.
• Quantitative objectives for quality and process performance are established and used as criteria in managing processes. Quantitative objectives are based on the needs of the customer, end users, organization, and process implementers. Quality and process performance are understood in statistical terms and are managed throughout the life of the processes.
• For these processes, detailed measures of process performance are collected and statistically analyzed. Special causes of process variation are identified and, where appropriate, the sources of special causes are corrected to prevent future occurrences.
• Quality and process performance measures are incorporated into the organizations measurement repository to support fact-based decision making in the future.
• A critical distinction between maturity level 3 and maturity level 4 is the predictability of process performance. At maturity level 4, the performance of processes is controlled using statistical and other quantitative techniques, and is quantitatively predictable. At maturity level 3, processes are only qualitatively predictable.

Maturity Level 5 – Optimizing: Company has accomplished all of the above and can now begin to see patterns in performance over time, so it can tweak its processes in order to improve productivity and reduce defects in software development across the entire organization.

In detail we can describe it as given below:

• At maturity level 5, an organization has achieved all the specific goals of the process areas assigned to maturity levels 2, 3, 4, and 5 and the generic goals assigned to maturity levels 2 and 3.
• Processes are continually improved based on a quantitative understanding of the common causes of variation inherent in processes.
• Maturity level 5 focuses on continually improving process performance through both incremental and innovative technological improvements.
• Quantitative process-improvement objectives for the organization are established, continually revised to reflect changing business objectives, and used as criteria in managing process improvement.
• The effects of deployed process improvements are measured and evaluated against the quantitative process-improvement objectives. Both the defined processes and the organization’s set of standard processes are targets of measurable improvement activities.
• Optimizing processes that are agile and innovative depends on the participation of an empowered workforce aligned with the business values and objectives of the organization.
• The organization’s ability to rapidly respond to changes and opportunities is enhanced by finding ways to accelerate and share learning. Improvement of the processes is inherently part of everybody’s role, resulting in a cycle of continual improvement.
• A critical distinction between maturity level 4 and maturity level 5 is the type of process variation addressed. At maturity level 4, processes are concerned with addressing special causes of process variation and providing statistical predictability of the results. Though processes may produce predictable results, the results may be insufficient to achieve the established objectives. At maturity level 5, processes are concerned with addressing common causes of process variation and changing the process (that is, shifting the mean of the process performance) to improve process performance (while maintaining statistical predictability) to achieve the established quantitative process-improvement objectives.

What is Validation in software testing? or What is software validation?

Validation is determining if the system complies with the requirements and performs functions for which it is intended and meets the organization’s goals and user needs.

• Validation is done at the end of the development process and takes place after verifications are completed.
• It answers the question like: Am I building the right product?
• Am I accessing the right data (in terms of the data required to satisfy the requirement).
• It is a High level activity.
• Performed after a work product is produced against established criteria ensuring that the product integrates correctly into the environment.
• Determination of correctness of the final software product by a development project with respect to the user needs and requirements.
  

Software verification and validation

According to the Capability Maturity Model (CMM) we can also define validation as The process of evaluating software during or at the end of the development process to determine whether it satisfies specified requirements. [IEEE-STD-610].

A product can pass while verification, as it is done on the paper and no running or functional application is required. But, when same points which were verified on the paper is actually developed then the running application or product can fail while validation. This may happen because when a product or application is build as per the specification but these specifications are not up to the mark hence they fail to address the user requirements.

Advantages of Validation:

1. During verification if some defects are missed then during validation process it can be caught as failures.
2. If during verification some specification is misunderstood and development had happened then during validation process while executing that functionality the difference between the actual result and expected result can be understood.
3. Validation is done during testing like feature testing, integration testing, system testing, load testing, compatibility testing, stress testing, etc.
4. Validation helps in building the right product as per the customer’s requirement and helps in satisfying their needs.

Validation is basically done by the testers during the testing. While validating the product if some deviation is found in the actual result from the expected result then a bug is reported or an incident is raised. Not all incidents are bugs. But all bugs are incidents. Incidents can also be of type ‘Question’ where the functionality is not clear to the tester.
Hence, validation helps in unfolding the exact functionality of the features and helps the testers to understand the product in much better way. It helps in making the product more user friendly.

What is Verification in software testing? or What is software verification?

Verification makes sure that the product is designed to deliver all functionality to the customer.

• Verification is done at the starting of the development process. It includes reviews and meetings, walk-throughs, inspection, etc. to evaluate documents, plans, code, requirements and specifications.
• Suppose you are building a table. Here the verification is about checking all the parts of the table, whether all the four legs are of correct size or not. If one leg of table is not of the right size it will imbalance the end product. Similar behavior is also noticed in case of the software product or application. If any feature of software product or application is not up to the mark or if any defect is found then it will result into the failure of the end product. Hence, verification is very important. It takes place at the starting of the development process.

Software verification and validation

• 
  

  Software verification and validation
• It answers the questions like: Am I building the product right?
• Am I accessing the data right (in the right place; in the right way).
• It is a Low level activity
• Performed during development on key artifacts, like walkthroughs, reviews and inspections, mentor feedback, training, checklists and standards.
• Demonstration of consistency, completeness, and correctness of the software at each stage and between each stage of the development life cycle.

According to the Capability Maturity Model (CMM) we can also define verification as the process of evaluating software to determine whether the products of a given development phase satisfy the conditions imposed at the start of that phase. [IEEE-STD-610].

Advantages of Software Verification :

1. Verification helps in lowering down the count of the defect in the later stages of development.
2. Verifying the product at the starting phase of the development will help in understanding the product in a better way.
3. It reduces the chances of failures in the software application or product.
4. It helps in building the product as per the customer specifications and needs.

What is Software Quality?

Quality software is reasonably bug or defect free, delivered on time and within budget, meets requirements and/or expectations, and is maintainable.

ISO 8402-1986 standard defines quality as  “the totality of features and characteristics of a product or service that bears its ability to satisfy stated or implied needs.”

Key aspects of quality for the customer include:

• Good design – looks and style
• Good functionality – it does the job well
• Reliable – acceptable level of breakdowns or failure
• Consistency
• Durable – lasts as long as it should
• Good after sales service
• Value for money

Good design – looks and style:
It is very important to have a good design. The application or product should meet all the requirement specifications and at the same time it should be user friendly. The customers are basically attracted by the good looks and style of the application. The right color combinations, font size and the styling of the texts and buttons are very important.
Good functionality – it does the job well:
Along with the good looks of the application or the product it’s very important that the functionality should be intact. All the features and their functionality should work as expected. There should not be any deviation in the actual result and the expected result.
Reliable – acceptable level of breakdowns or failure:
After we have tested for all the features and their functionalities it also very important that the application or product should be reliable. For example: There is an application of saving the students records. This application should save all the students records and should not fail after entering 100 records. This is called reliability.
Consistency:
The software should have consistency across the application or product. Single software can be multi dimensional. It is very important that all the different dimensions should behave in a consistent manner.
Durable – lasts as long as it should:
The software should be durable. For example if software is being used for a year and the number of data has exceed 5000 records then it should not fail if number of records increases. The software product or application should continue to behave in the same way without any functional breaks.
Good after sales service:
Once the product is shipped to the customers then maintenance comes into the picture. It is very important to provide good sales services to keep the customers happy and satisfied. For example if after using the product for six months the customer realizes to make some changes to the application then those changes should be done as fast as possible and should be delivered to the customers on time with quality.
Value for money:
It’s always important to deliver the product to the customers which have value for money. The product should meet the requirement specifications. It should work as expected, should be user friendly. We should provide good services to the customers. Other than the features mentioned in the requirement specifications some additional functionality could be given to the customers which they might not have thought of. These additional functionalities should make their product more user friendly and easy to use. This also adds value for money.

What is independent testing? It’s benefits and risks

The degree of independence avoids author bias and is often more effective at finding defects and failures.

There is several level of independence which is listed here from the lowest level of independence to the highest:
i. Tests by the person who wrote the item.
ii. Tests by another person within the same team, like another programmer.
iii.Tests by the person from some different group such as an independent test team.
iv.Tests by a person from a different organization or company, such as outsourced testing or certification by an external body.

When we think about how independent the test team is? It is really very important to understand that independence is not an either/or condition, but a range:

• At one end of the range lies the absence of independence, where the programmer performs testing within the programming team.
• Moving toward independence, we find an integrated tester or group of testers working alongside the programmers, but still within and reporting to the development manager.
• Then moving little bit more towards independence we might find a team of testers who are independent and outside the development team, but reporting to project management.
• Near the other end of the continuum lies complete independence. We might see a separate test team reporting into the organization at a point equal to the development or project team. We might find specialists in the business domain (such as users of the system), specialists in technology (such as database experts), and specialists in testing (such as security testers, certification testers, or test automation experts) in a separate test team, as part of a larger independent test team, or as part of a contract, outsourced test team.

Benefits of independence testing:

• An independent tester can repeatedly find out more, other, and different defects than a tester working within a programming team – or a tester who is by profession a programmer.
• While business analysts, marketing staff, designers, and programmers bring their own assumptions to the specification and implementation of the item under test, an independent tester brings a different set of assumptions to testing and to reviews, which often helps in exposing the hidden defects and problems
• An independent tester who reports to senior management can report his results honestly and without any concern for reprisal that might result from pointing out problems in coworkers’ or, worse yet, the manager’s work.
• An independent test team often has a separate budget, which helps ensure the proper level of money is spent on tester training, testing tools, test equipment, etc.
• In addition, in some organizations, testers in an independent test team may find it easier to have a career path that leads up into more senior roles in testing.

Risks of independence and integrated testing:

• There is a possibility that the testers and the test team can get isolated. This can take the form of interpersonal isolation from the programmers, the designers, and the project team itself, or it can take the form of isolation from the broader view of quality and the business objectives (e.g., obsessive focus on defects, often accompanied by a refusal to accept business prioritization of defects).
• This leads to communication problems, feelings of unfriendliness and hostility.
• Lack of identification with and support for the project goals, spontaneous blame festivals and political backstabbing.
• Even well-integrated test teams can suffer problems. Other project stakeholders might come to see the independent test team – rightly or wrongly – as a bottleneck and a source of delay. Some programmers give up their responsibility for quality, saying, ‘Well, we have this test team now, so why do I need to unit test my code?’

What is the Psychology of testing?

In this section we will discuss:

• The comparison of the mindset of the tester and the developer.
• The balance between self-testing and independent testing.
• There should be clear and courteous communication and feedback on defects between tester and developer.

Comparison of the mindset of the tester and developer:
The testing and reviewing of the applications are different from the analysing and developing of it. By this we mean to say that if we are building or developing applications we are working positively to solve the problems during the development process and to make the product according to the user specification. However while testing or reviewing a product we are looking for the defects or failures in the product. Thus building the software requires a different mindset from testing the software.

The balance between self-testing and independent testing:
The comparison made on the mindset of the tester and the developer in the above article is just to compare the two different perspectives. It does not mean that the tester cannot be the programmer, or that the programmer cannot be the tester, although they often are separate roles. In fact programmers are the testers. They always test their component which they built. While testing their own code they find many problems so the programmers, architect and the developers always test their own code before giving it to anyone. However we all know that it is difficult to find our own mistakes. So, programmers, architect, business analyst depend on others to help test their work. This other person might be some other developer from the same team or the Testing specialists or professional testers. Giving applications to the testing specialists or professional testers allows an independent test of the system.

This degree of independence avoids author bias and is often more effective at finding defects and failures.

There is several level of independence in software testing which is listed here from the lowest level of independence to the highest:
i.  Tests by the person who wrote the item.
ii.  Tests by another person within the same team, like another programmer.
iii.  Tests by the person from some different group such as an independent test team.
iv.  Tests by a person from a different organization or company, such as outsourced testing or certification by an external body.

Clear and courteous communication and feedback on defects between tester and  developer:
We all make mistakes and we sometimes get annoyed and upset or depressed when   someone points them out. So, when as testers we run a test which is a good test from our viewpoint because we found the defects and failures in the software. But at the same time we need to be very careful as how we react or report the defects and failures to the programmers. We are pleased because we found a good bug but how will the requirement analyst, the designer, developer, project manager and customer react.

• The people who build the application may react defensively and take this reported defect as personal criticism.
• The project manager may be annoyed with everyone for holding up the project.
• The customer may lose confidence in the product because he can see defects.

Because testing can be seen as destructive activity we need to take care while reporting our defects and failures as objectively and politely as possible.

The balance between self-testing and independent testing

What is fundamental test process in software testing?

Testing is a process rather than a single activity. This process starts from test planning then designing test cases, preparing for execution and evaluating status till the test closure. So, we can divide the activities within the fundamental test process into the following basic steps:

1)    Planning and Control
2)    Analysis and Design
3)    Implementation and Execution
4)    Evaluating exit criteria and Reporting
5)    Test Closure activities

1)    Planning and Control:

Test planning has following major tasks:
i.  To determine the scope and risks and identify the objectives of testing.
ii. To determine the test approach.
iii. To implement the test policy and/or the test strategy. (Test strategy is an outline that describes the testing portion of the software development cycle. It is created to inform PM, testers and developers about some key issues of the testing process. This includes the testing objectives, method of testing, total time and resources required for the project and the testing environments.).
iv. To determine the required test resources like people, test environments, PCs, etc.
v. To schedule test analysis and design tasks, test implementation, execution and evaluation.
vi. To determine the Exit criteria we need to set criteria such as Coverage criteria. (Coverage criteria are the percentage of statements in the software that must be executed during testing. This will help us track whether we are completing test activities correctly. They will show us which tasks and checks we must complete for a particular   level of testing before we can say that testing is finished.)

 Test control has the following major tasks:
i.  To measure and analyze the results of reviews and testing.
ii.  To monitor and document progress, test coverage and exit criteria.
iii.  To provide information on testing.
iv.  To initiate corrective actions.
v.   To make decisions.

2)  Analysis and Design:

Test analysis and Test Design has the following major tasks:
i.   To review the test basis. (The test basis is the information we need in order to start the test analysis and   create our own test cases. Basically it’s a documentation on which test cases are based, such as requirements, design specifications, product risk analysis, architecture and interfaces. We can use the test basis documents to understand what the system should do once built.)
ii.   To identify test conditions.
iii.  To design the tests.
iv.  To evaluate testability of the requirements and system.
v.  To design the test environment set-up and identify and required infrastructure and tools.

3)  Implementation and Execution:
During test implementation and execution, we take the test conditions into test cases and procedures and other testware such as scripts for automation, the test environment and any other test infrastructure. (Test cases is a set of conditions under which a tester will determine whether an   application is working correctly or not.)
(Testware is a term for all utilities that serve in combination for testing a software like scripts, the test environment and any other test infrastructure for later reuse.)

Test implementation has the following major task:
i.  To develop and prioritize our test cases by using techniques and create test data for those tests. (In order to test a software application you need to enter some data for testing most of the features. Any such specifically identified data which is used in tests is known as test data.)
We also write some instructions for carrying out the tests which is known as test procedures.
We may also need to automate some tests using test harness and automated tests scripts. (A test harness is a collection of software and test data for testing a program unit by running it under different conditions and monitoring its behavior and outputs.)
ii. To create test suites from the test cases for efficient test execution.
(Test suite is a collection of test cases that are used to test a software program   to show that it has some specified set of behaviours. A test suite often contains detailed instructions and information for each collection of test cases on the system configuration to be used during testing. Test suites are used to group similar test cases together.)
iii. To implement and verify the environment.

Test execution has the following major task:
i.  To execute test suites and individual test cases following the test procedures.
ii. To re-execute the tests that previously failed in order to confirm a fix. This is known as confirmation testing or re-testing.
iii. To log the outcome of the test execution and record the identities and versions of the software under tests. The test log is used for the audit trial. (A test log is nothing but, what are the test cases that we executed, in what order we executed, who executed that test cases and what is the status of the test case (pass/fail). These descriptions are documented and called as test log.).
iv. To Compare actual results with expected results.
v. Where there are differences between actual and expected results, it report discrepancies as Incidents.

4)  Evaluating Exit criteria and Reporting:
Based on the risk assessment of the project we will set the criteria for each test level against which we will measure the “enough testing”. These criteria vary from project to project and are known as exit criteria.
Exit criteria come into picture, when:
— Maximum test cases are executed with certain pass percentage.
— Bug rate falls below certain level.
— When achieved the deadlines.

Evaluating exit criteria has the following major tasks:
i.  To check the test logs against the exit criteria specified in test planning.
ii.  To assess if more test are needed or if the exit criteria specified should be changed.
iii.  To write a test summary report for stakeholders.

5)  Test Closure activities:
Test closure activities are done when software is delivered. The testing can be closed for the other reasons also like:

• When all the information has been gathered which are needed for the testing.
• When a project is cancelled.
• When some target is achieved.
• When a maintenance release or update is done.

Test closure activities have the following major tasks:
i.  To check which planned deliverables are actually delivered and to ensure that all incident reports have been resolved.
ii. To finalize and archive testware such as scripts, test environments, etc. for later reuse.
iii. To handover the testware to the maintenance organization. They will give support to the software.
iv To evaluate how the testing went and learn lessons for future releases and projects.

What are the principles of testing?

Principles of Testing – There are seven principles of testing. They are as follows:

1) Testing shows presence of defects: Testing can show the defects are present, but cannot prove that there are no defects. Even after testing the application or product thoroughly we cannot say that the product is 100% defect free. Testing always reduces the number of undiscovered defects remaining in the software but even if no defects are found, it is not a proof of correctness.

2) Exhaustive testing is impossible: Testing everything including all combinations of inputs and preconditions is not possible. So, instead of doing the exhaustive testing we can use risks and priorities to focus testing efforts. For example: In an application in one screen there are 15 input fields, each having 5 possible values, then to test all the valid combinations you would need 30  517  578  125  (5¹⁵) tests. This is very unlikely that the project timescales would allow for this number of tests. So, accessing and managing risk is one of the most important activities and reason for testing in any project.

3) Early testing: In the software development life cycle testing activities should start as early as possible and should be focused on defined objectives.

4) Defect clustering: A small number of modules contains most of the defects discovered during pre-release testing or shows the most operational failures.

5) Pesticide paradox: If the same kinds of tests are repeated again and again, eventually the same set of test cases will no longer be able to find any new bugs. To overcome this “Pesticide Paradox”, it is really very important to review the test cases regularly and new and different tests need to be written to exercise different parts of the software or system to potentially find more defects.

6) Testing is context dependent: Testing is basically context dependent. Different kinds of sites are tested differently. For example, safety – critical software is tested differently from an e-commerce site.

7) Absence – of – errors fallacy: If the system built is unusable and does not fulfil the user’s needs and expectations then finding and fixing defects does not help.