Software Testing Tutorial #10 - Iterative Model in Software Engineering

Summary

This tutorial explains the iterative development model in software testing, comparing it with the waterfall and V-model. It highlights the drawbacks of traditional models, like long delivery times, and introduces the iterative approach where development phases repeat in shorter cycles (4-8 weeks), allowing for quicker releases and better customer feedback. The tutorial provides a practical example of building an e-commerce application in phases, explaining how features are added incrementally. It also differentiates iterative development from Agile, noting that Agile is more comprehensive while following a similar cycle.

Takeaways

• 😀 The iterative development model was introduced to address the long delivery times in traditional models like the waterfall and V-model.
• 🚀 In the iterative model, the development cycle (requirements, design, development, testing, deployment) is repeated in shorter iterations, typically lasting 4-8 weeks.
• ⏳ Unlike the waterfall model, which could take up to two years, the iterative model allows for quicker delivery of working software.
• 🛠 Each iteration includes the same phases: requirements, design, development, testing, and deployment, but focuses on delivering small, incremental updates.
• 🔄 New features and enhancements are added incrementally in each iteration, improving the software progressively over time.
• 💡 An example of iterative development is building an e-commerce app, where the login page is created in the first iteration, and additional features like password recovery are added in later iterations.
• ⏱ While the iterative model shortens delivery time, it still follows a phased approach similar to waterfall, where requirements must be frozen before development starts.
• 📉 The iterative model improves feedback loops, as each iteration delivers a working product, allowing for faster feedback from customers.
• 💻 Agile and Scrum also follow an iterative approach with sprints, but agile introduces a broader mindset and values beyond just the development cycles.
• 🤔 Agile addresses more of the limitations found in waterfall, V-model, and iterative development, offering a more dynamic approach to software development.

Q & A

What is the main purpose of the iterative development model?

The iterative development model was introduced to address the issues of delayed software delivery found in the waterfall and V-models. It enables faster value delivery to customers by allowing for shorter cycles of development and repeated iterations.

What are the key differences between the V-model and iterative development model?

While both the V-model and iterative development model involve testing at each phase, the key difference is that the V-model still results in long delivery cycles, while the iterative model reduces the delivery time by repeating phases in shorter cycles of 4-8 weeks.

Why is the waterfall model considered inefficient for modern software development?

The waterfall model requires a long time to deliver software, sometimes up to two years, which is not suitable for today's dynamic market conditions where faster value delivery is crucial. This is why iterative models were introduced.

How does the iterative development model handle requirements compared to the waterfall model?

In the iterative development model, requirements are broken down into smaller phases and are continuously revisited with each iteration. This contrasts with the waterfall model, where requirements are gathered all at once at the beginning of the project and remain static.

What happens during each phase of the iterative development model?

Each phase in the iterative development model follows a cycle of requirement gathering, design, development, testing, and deployment. This cycle repeats with each iteration until all requirements are fully implemented.

What are some examples of features that might be added during iterative phases?

In an example of building an e-commerce application, the first iteration might include a login page with basic fields, and later iterations might add features like password recovery, social media login options, or improved design elements.

What are the main advantages of the iterative development model?

The primary advantages are faster feedback and quicker delivery of working software to the customer, allowing for faster validation and adjustments based on feedback.

What is the major disadvantage of the iterative development model?

Despite shorter cycles, the iterative development model still follows a phased approach where requirements, design, development, and testing are done sequentially within each cycle, which can lead to delays if requirements need frequent revisions.

Is agile development the same as the iterative development model?

No, agile development is not the same as the iterative development model, though they share similarities in using short cycles. Agile goes beyond the iterative model by promoting a more flexible, customer-centric approach and continuous improvement, while iterative still follows a phased structure.

How does iterative development improve feedback loops?

In iterative development, shorter cycles allow for quicker feedback from customers after each iteration. This feedback can be incorporated into future iterations, leading to continuous improvement of the product.

Outlines

00:00

🛠 Introduction to Iterative Development Model

The video begins by introducing the iterative development model, following a brief recap of the waterfall and V-model approaches. It highlights the limitations of both models, such as lengthy delivery times, even with the V-model's inclusion of testing in every phase. The iterative model was introduced to address these challenges, aiming for quicker value delivery through shorter, repeated cycles of development and testing.

05:01

🔄 Phases of Iterative Development

This section explains the phases of the iterative development model, which follow a repeated cycle similar to a shortened version of the waterfall model. Key phases include requirements, design, development, testing, and deployment. Iterations typically last between four and eight weeks, allowing frequent releases of software. Each iteration adds more functionality to the software until all customer requirements are met, avoiding long delivery times seen in traditional models.

10:01

⚙️ Shorter Cycles and Incremental Builds

The video describes the shorter cycle times in iterative development, contrasting them with the lengthy timelines of the waterfall approach, which could extend to two years. It further details how, in each iteration, the team develops incremental features. For example, in an e-commerce application, initial iterations might build basic functionality like a login page, while subsequent iterations add features such as ‘Forgot Password’ and third-party login options, ensuring quicker, iterative releases.

🚀 Benefits and Drawbacks of Iterative Development

This segment explores the advantages of iterative development, such as delivering functional software more quickly to the customer. However, a phased approach still remains, where each phase (requirements, design, etc.) must be completed before moving on. Although the process is faster and allows better feedback, it doesn’t completely eliminate the rigid phase structure present in older models.

🌱 Introduction to Agile and its Distinctions

The video introduces Agile methodology, noting its similarity to the iterative model but emphasizing that Agile is a more advanced approach. Agile is not only about iterations but also about mindset and values that address the drawbacks of both waterfall and iterative models. Agile frameworks like Scrum break development into smaller sprints but involve more flexible, customer-focused practices compared to traditional iterative methods.

📚 Conclusion and Practical Tips for Interviews

The tutorial concludes with practical advice for testers, emphasizing the importance of understanding these development models, especially for job interviews. It encourages viewers to be prepared to explain the differences between iterative and Agile approaches, which are often confused, and stresses that this foundational knowledge will be useful in real-world software testing and development projects.

Keywords

💡Iterative Development Model

The iterative development model is a software development approach where the development cycle is repeated multiple times, delivering smaller, incremental improvements. In the video, it is presented as a response to the long delivery times in waterfall and V-models, enabling quicker releases with shorter phases (1-2 months).

💡Waterfall Model

The Waterfall Model is a traditional software development approach where each phase (requirements, design, development, testing, deployment) is completed sequentially. It’s criticized for its long delivery times, as described in the video, which led to the introduction of more flexible models like the iterative approach.

💡V-Model

The V-Model is an extension of the waterfall model, where testing is involved in each development phase, creating a 'V' shape with parallel development and testing stages. However, the video highlights its drawback of long delivery durations, similar to the waterfall model.

💡Phased Approach

A phased approach refers to dividing the software development lifecycle into distinct phases like requirements gathering, design, coding, and testing. While the iterative model also follows this phased approach, the video emphasizes that it improves on the long durations seen in the waterfall and V-models by shortening the cycles.

💡Feedback Loop

The feedback loop is the mechanism by which feedback from each iteration of development is incorporated into subsequent iterations. In the iterative development model, as discussed in the video, this loop allows for better feedback and quicker improvements compared to waterfall and V-models.

💡Agile

Agile is a software development methodology that emphasizes flexibility, iterative progress, and faster delivery. The video clarifies that although agile also uses short cycles like the iterative model, it offers a more comprehensive set of values and practices, distinguishing it from traditional iterative approaches.

💡Sprint

A sprint is a time-boxed iteration in agile development, typically lasting 2-4 weeks. The video briefly mentions sprints in the context of agile, contrasting them with the iterative model’s phases, as sprints offer even more flexibility and continuous delivery of features.

💡User Acceptance Testing

User Acceptance Testing (UAT) is the phase where the end-users test the software to ensure it meets their requirements. In the video, this type of testing is associated with the V-model, where testing occurs in each phase of the development lifecycle.

💡Incremental Build

Incremental build refers to the process of building the software in small, usable parts. The video illustrates this by using an example of an e-commerce application, where the login functionality is built first, followed by enhancements like forgot password or social media sign-up in subsequent iterations.

💡Value Delivery

Value delivery refers to the process of providing a functional product to customers quickly, ensuring that they receive usable software in shorter cycles. The video emphasizes the importance of fast value delivery in modern market conditions, where waiting for long periods, like in the waterfall model, is not feasible.

Highlights

Introduction to iterative development model as a response to drawbacks of the waterfall and V-model.

Iterative development model addresses the need for faster delivery in dynamic market conditions, where traditional models had long delivery timelines.

In iterative development, software is delivered in smaller, repeated cycles, with each phase (requirements, design, development, testing, and deployment) repeated in iterations.

Each iteration delivers a working piece of software in a shorter timeframe, typically within 4 to 8 weeks.

The iterative model allows phased software delivery, where features are incrementally added and improved upon in subsequent iterations.

Phased approach of the waterfall model is retained, but with shorter and repeated cycles for quicker releases.

Iterative model example: Building an e-commerce application incrementally, where initial iterations provide basic features, and subsequent ones add advanced functionalities like 'forgot password' or third-party logins.

The primary advantage of iterative development is that customers can see working software sooner, with feedback loops for improvements.

A notable disadvantage of iterative development is that the phased approach still exists, requiring requirements to be frozen before design and development can proceed.

Iterative model doesn't completely solve the problem of the phased approach, as design, development, and testing still happen in sequence within iterations.

Agile development also follows iterative cycles but introduces additional principles, making it more advanced than the traditional iterative model.

Agile development is not identical to iterative development—Agile involves more comprehensive changes to methodology, mindset, and values.

Agile, especially Scrum, enhances iterative processes by introducing concepts like sprints and focuses on constant feedback and flexibility.

Iterative development models, while improving over waterfall and V-models, still don't address all modern software development challenges—Agile aims to fill that gap.

Understanding iterative development is essential for software testers and developers, especially when transitioning to more adaptive and Agile environments.

Transcripts

hello everyone welcome again in this

software testing tutorial

we are going to learn iterative

development model

so in the previous two tutorials we have

seen about the

waterfall development model and the v

model

and some of the advantages and

disadvantages basically so in the

waterfall model there were a couple of

disadvantages because of which

v-model was introduced and even

the model couldn't address some of the

disadvantages that we

you know used to have in the software

development lifecycle right

so iterative development model came

after

uh you know those methodologies had some

of the drawbacks

so say for example even with the v-model

what issues we had

is even though testing was involved in

each and every

phase of the v model still the

duration of the delivery or the value

delivery

uh was pretty long so the if you if you

you know if you want to

rephrase or uh you want to

see the v model so it was something like

you had

you know the requirements and then

the coding so there were a couple of

phases there uh

in between so design development etc so

uh and then the testing was sort of

parallely so here there was user

acceptance testing then there was you

know

system testing integration testing

accordingly right so testing was

involved in each and every phase

but the duration was still lengthy right

so duration was still long for

the v model as well as it was in the

waterfall model

now if you have a delivery in current

scenario in the current dynamic scenario

or the market conditions

you can't wait for delivering the

software for you know like two years

okay so you have to add the value or

deliver the value to the customers

pretty quickly and

that is why you have to deliver software

very quickly

and in order to address those issues of

delivery or delayed

delivery to the customer iterative

development model was introduced

so iterative development model what

they do is uh you basically repeat

the same cycle so for example in the

waterfall we had

certain phases right so we we had phases

say for example

in the waterfall so for example if i say

phase

one right so what if all we had the

phase

of requirements

then we have design

then develop okay so develop

uh test and then

deploy right and then maintenance

so these were some of the phases right

so what happened in the iterative

development approach

is basically they had these phases and

these

phases will be repeated so say for

example phase one

will have the requirement then design

develop

test and deploy so this will be sort of

you know like a quick

release of one to two months so every

four

weeks to eight weeks there could be you

know like

a drop of software coming or deployment

happening

and then the same cycle so you see

requirement

design development test deploy the same

cycle

keeps repeating so there will be another

phase or

a release of phase two or released to

whatever

the organization want to call it and

this

whole process of requirements

so requirement i'll say requirement

design

develop and then

you know test

and deploy right so all

these all the same phases whatever we

have seen in the waterfall model except

the maintenance phase will keep

repeating in each of these iteration

unless and until

all the requirements that have been

given by the customers

are being completely built and deployed

in different phases so there could be

you know like

five phases ten phases so you know there

there could be multiple phases

depending on how the complex software

is and how many requirements you are

trying to build so there will be another

phase

phase three starting right so this is

how

iterative development model works

now in iterative development model there

wasn't much change the only

change was basically to have

shorter iterations or shorter cycles

and within those cycle you fit a smaller

waterfall model

okay so here if you see this is one

cycle

or iteration okay so iterative came

from iteration so which is nothing but

the duration

of whatever you know weeks or months so

it will be a shorter duration as

compared to

the waterfall approach so in waterfall

approach it was mostly like

six months to one year to you know maybe

it will extend up to two years as well

but in iterative it will come down to

one month or two month

depending on how the organization or

project team wants to manage

and then in the first iteration they'll

pick certain features

and they'll try to build some of the

skeleton or the

initial features then they'll pick

another set of features

in the second iteration right so second

iteration

and they'll build they'll do the you

know requirement analysis

and then design and develop test and

deploy similarly

this whole process will keep continuing

like that

okay now let's take an example of how

um the software will be built

incrementally or basically with the

iterative development approach now say

for example

you want to build a application

um e-commerce application which

has the login functionality right so for

example in the iteration one what team

might do is they will say in first

iteration we'll build

the login page right so we'll build a

skeleton

so we'll have a login page okay and on

the login page we'll just have

the username and password field okay

and the login button so that will be

built in the first iteration so all this

will be built

tested and deployed okay

then um you know after this

they want to add more features right or

more requirements so

the next what they'll do is they might

add you know

they they will be beautify the page so

they'll

add you know more css to beautify the

page and then they might add

forgot so forgot

password functionality in the next

iteration okay or in the next next phase

so this is how they will keep

incrementally adding more functionality

in the iterations in the iterative

development model

so in the first page they'll be in the

first phase they'll do some features in

the next phase they'll

add more features like forgot password

you know

forgot username so all those features

might be available in the next phase

then they in the third phase they might

pick more

features so for example signing up with

the

google signing up with facebook account

so those features can come in

third phase but you can see the

advantage here is

that instead of waiting for two years to

get the whole

you know release or the software you can

get the release very quickly so

there is something working available for

the customer to have a look how

the implementation has happened and

whether it is

meeting the customer's requirement right

so that was the advantage of iterative

development

model but the disadvantage is again it

didn't address

that phased approach right even though

the cycle is still

short but there is still phased approach

requirement need to be frozen then

design will start then development will

start test will start and then

deployment will happen right

so phased approach is still there but

because cycles are

reduced or there are more cycles so

there is still a lot

better you know feedback loop in there

now

um agile is one

you know development approach very

recent uh development approach which is

basically scrum

um and agile

is also or it also follows iterative

approach

right so there are sprints and then

within sprints you

develop small features but you shouldn't

confuse

that agile is exactly similar to what

iterative development model is

agile is a lot more as compared to

iterative development model so it is

similar but it is not same to iterative

development model

please note that right so do not get

confused that

agile or extreme programming they are

you know

similar or exactly same as iterative

development model so

they follow that cadence they follow

that um

you know smaller iterations but

there is a lot more in agile which i'll

explain uh in later tutorials as

compared to iterative development model

so in agile a lot more

drawbacks that were there in waterfall

approaching the model

in iterative model as well they were

being addressed and it's

totally a different you know mindset and

values that needs to be followed when

you are following agile methodology

or any agile development approach like

scrum

so that is all for this particular

tutorial about iterative development

model

hope it was helpful and clear um and

will be helpful for you in your

interviews if you are going for

an interview and somebody asked for what

is iterative development model

whether it's similar to agile or what is

the similarity and

so all those things you can answer to

the interviewer

and even if you are working in any

project it will be really helpful to

know

all these basics before you can actually

become a really good tester

so that's all for this tutorial please

do share and subscribe and thank you for

watching