ISTQB Agile Tester #39 - What is Test Driven Development (TDD) in Agile

Summary

This tutorial introduces Test-Driven Development (TDD), a practice popularized by Extreme Programming but applicable across various agile methodologies including Scrum and Kanban, and even sequential ones like Waterfall. TDD emphasizes writing automated test cases before coding, guiding developers to produce code that passes these tests. The TDD cycle involves adding test cases, writing code to pass them, and refactoring until all tests are successful. Benefits include comprehensive test coverage and fewer defects, as the code is developed with a clear focus on meeting defined test expectations.

Takeaways

• 🌟 Test-Driven Development (TDD) is a software development approach that became popular through Extreme Programming but is also used in other agile methodologies like Scrum and Kanban, as well as in sequential lifecycles like Waterfall or V-model.
• 🔍 TDD focuses developers on clearly defined expected results by using automated tests, which are integral to continuous integration and are used to guide code development.
• 📝 The TDD process involves writing test cases before adding any functionality to the code. This means that developers start coding with the aim to make these tests pass.
• 👥 In an agile team following TDD, the role of the tester is to provide test cases and help the team identify scenarios that need to be tested.
• 🔄 The three main steps of TDD are: writing a failing unit test, making the unit test pass by coding, and then refactoring the code to ensure it passes the written tests.
• 🔄 TDD uses a cyclical process: write a failing test, make the test pass, and then repeat. This cycle continues with the addition of new test cases and code refactoring until all tests pass.
• 🛡️ One of the key benefits of TDD is high test coverage because code is written only after the test cases are defined, ensuring that all written code is covered by tests.
• 🐛 Fewer defects are produced in TDD because the process starts with defining test cases, which means the entire codebase is tested against these cases, reducing the number of bugs.
• 💡 TDD encourages a clear understanding of expected outcomes and promotes a disciplined approach to coding by ensuring that tests are passed before moving on to new features.
• 🚀 The tutorial provides an overview of what TDD is, the TDD cycle, and highlights the benefits of using this development approach, emphasizing its value in creating robust and reliable software.

Q & A

What is Test-Driven Development (TDD)?

Test-Driven Development (TDD) is a software development approach where tests are written before the actual code. It emphasizes writing automated tests to guide the development process, ensuring that the code fulfills the expected results.

How did TDD become popular?

TDD became popular through the Extreme Programming (XP) approach, which is one of the agile development methodologies. It is now widely used in various agile and even traditional development methodologies like Scrum, Kanban, Waterfall, and V-model.

What is the role of a tester in a TDD approach?

In a TDD approach, the role of a tester is to provide test cases and help the team identify the scenarios that need to be tested. Testers work collaboratively with developers to ensure that the tests are well-defined and cover all necessary functionality.

What is the first step in the TDD process?

The first step in the TDD process is to add test cases before any functionality is added to the code. Developers write tests that will initially fail, as the corresponding code has not yet been implemented.

What does a developer do after writing the initial failing tests?

After writing the initial failing tests, developers start coding to make the tests pass. They write the minimum amount of code necessary to fulfill the test cases and ensure that the tests pass.

What is the purpose of refactoring in TDD?

Refactoring in TDD is the process of improving the code's structure without changing its external behavior. It is done after the tests pass to ensure that the code is clean, maintainable, and efficient.

What is the TDD cycle?

The TDD cycle involves writing a failing unit test, making the unit test pass by writing the necessary code, and then refactoring the code to improve its quality. This cycle is repeated until all test cases are passed.

How does TDD contribute to better test coverage?

TDD contributes to better test coverage because it requires writing test cases before any code is written. This ensures that every piece of code is developed with a corresponding test case, leading to comprehensive test coverage.

What are some benefits of using TDD?

Some benefits of using TDD include improved code quality, better test coverage, fewer defects, and a clearer focus on expected results. It also encourages a more collaborative and iterative development process.

Can TDD be used in non-agile methodologies?

Yes, TDD can be used in non-agile methodologies as well. It has been adopted in sequential lifecycle methodologies like Waterfall or V-model, where it can still provide benefits in terms of test coverage and code quality.

How does TDD help in reducing defects in software development?

TDD helps in reducing defects by ensuring that code is developed in small, testable increments. Since tests are written before the code, any issues are caught early in the development process, leading to fewer defects in the final application.

Outlines

00:00

🔧 Introduction to Test-Driven Development (TDD)

This paragraph introduces the concept of Test-Driven Development (TDD) and its lifecycle. TDD became popular through the extreme programming approach, which is one of several agile development methodologies. The speaker explains that TDD is not limited to extreme programming and can be applied to other agile approaches like Scrum or Kanban, as well as more traditional methodologies such as the waterfall model. The paragraph emphasizes that TDD helps developers focus on expected results by using automated tests in continuous integration. It outlines the TDD approach, which involves writing test cases before adding functionality to the code, and then coding to make those tests pass, followed by refactoring the code to ensure it meets the test criteria. The speaker also describes the TDD process cycle, which includes adding test cases, writing code to pass those tests, and refactoring until all tests are passed, highlighting the iterative nature of TDD.

05:01

🛡 Benefits of Test-Driven Development

The second paragraph delves into the benefits of TDD. It highlights that TDD leads to better test coverage because the code is written with test cases already in place. This approach ensures that every part of the code is tested, resulting in fewer defects in the final application. The paragraph concludes by summarizing the tutorial's content, which includes an explanation of what TDD is, the TDD cycle, and the advantages of adopting this development methodology.

Keywords

💡Test-Driven Development (TDD)

Test-Driven Development (TDD) is a software development practice where tests are written before the actual code. It encourages simple designs and inspires confidence. In the context of the video, TDD is highlighted as a popular approach that originated from Extreme Programming but is also applicable in other agile methodologies like Scrum or Kanban, as well as traditional methodologies like Waterfall or V-model. The script emphasizes that TDD helps developers focus on expected results and uses automated tests for continuous integration.

💡Extreme Programming

Extreme Programming (XP) is one of the agile software development methodologies that emphasizes technical practices, communication, and customer satisfaction. The video mentions that TDD became popular through XP, indicating that XP played a significant role in promoting the practice of writing tests before writing the corresponding code.

💡Agile Development

Agile Development is a group of software development methodologies that promote iterative development, flexibility, and collaboration. The script discusses how TDD is not limited to XP but is also used in other agile approaches, emphasizing the adaptability of TDD within various agile frameworks.

💡Continuous Integration

Continuous Integration (CI) is a practice where developers frequently merge their code changes into a central repository, which then triggers automated builds and tests. The video explains that TDD uses automated tests that are part of the CI process, ensuring that new code changes do not break existing functionality.

💡Automated Tests

Automated Tests are scripts that run tests automatically to determine if the software works as expected. The script mentions that in TDD, tests are automated and used to guide the development of code, which means that developers write tests that will initially fail and then write code to make these tests pass.

💡Refactoring

Refactoring is the process of restructuring existing computer code without changing its external behavior to improve nonfunctional attributes of the software. In the video, refactoring is described as a step in the TDD cycle where developers improve the code to pass the written tests, ensuring the code is clean and efficient.

💡Unit Tests

Unit Tests are tests that validate that a single unit of the software code works as designed. The script explains that in TDD, unit tests are written before the actual development starts, and developers write code to make these unit tests pass.

💡Test Cases

Test Cases are defined sets of instructions that determine if a particular feature of a software program works as intended. The video script states that in TDD, test cases are added before adding any functionality into the code, which means they are the foundation for what the code needs to achieve.

💡Test Coverage

Test Coverage refers to the degree to which the software's code has been tested. The script highlights that TDD results in good test coverage because the code is written to fulfill the predefined test cases, ensuring that all parts of the code are tested.

💡Defects

Defects are errors or faults in a software program that cause it to behave in unintended ways. The video mentions that TDD leads to fewer defects because the code is developed with test cases in mind, which helps in identifying and fixing issues early in the development process.

💡Lifecycle

Lifecycle in the context of software development refers to the series of stages a software product goes through from its conception to retirement. The script describes the TDD lifecycle, which includes writing test cases, writing code to pass those tests, and refactoring until all tests are passed, as a continuous cycle that repeats until the software is complete.

Highlights

Test-driven development (TDD) became popular through the extreme programming approach.

TDD can be used in various agile development approaches, including Scrum and Kanban.

TDD is also applicable in sequential methodologies like waterfall or V-model.

TDD helps developers focus on clearly defined expected results.

Tests in TDD are automated and used in continuous integration.

TDD involves developing code guided by automated test cases.

In TDD, test cases are added before adding any functionality into the code.

Testers play a crucial role in providing test cases for TDD.

Developers start coding to make the tests pass.

The third step in TDD is refactoring the code to pass the written tests.

TDD process involves writing a failing unit test, making it pass, and repeating the process.

The TDD cycle includes adding test cases, watching tests fail, writing code, and refactoring until all tests pass.

TDD ensures high test coverage as code is written only after adding the test cases.

TDD results in fewer defects due to the initial focus on test cases.

The tutorial explains the TDD cycle and its benefits.

TDD is a valuable approach for improving software quality and reducing defects.

Transcripts

in this a stick you be agile test

acidification tutorial I'm going to talk

about what is test-driven development

and test-driven development lifecycle so

test-driven development became popular

through extreme programming approach so

we have seen that there were a couple of

agile development approach and extreme

programming was one of the approach and

test-driven development became popular

from extreme programming however the

test-driven development is being used in

other child development approaches as

well and you can use it in scrum or in

Kahneman wherever you want your project

wants you can use test-driven

development in the approaches in other

agile approaches and even some of the

sequential lifecycle sequential

methodologies like waterfall or V model

people used to our projects used to use

test-driven development approach as well

now test-driven development approach

helps developers focus on clearly

defined expected results the tests are

automated and are used in continuous

integration and Testament development is

used to develop code guided by automated

test cases now let's see what the

approach is so the test-driven

development approach is you add the test

cases before adding any functionality

into your code so before you actually or

before developer starts coding you add

the test cases so as a part of the test

team or in the agile development

approach once you join as a tester your

if your team is following the

test-driven development approach your

role is to provide the test cases for

the test-driven development approach and

help the team to identify the test cases

and the scenarios that need to be tested

and for the test development approach so

once the test cases are added defined by

you and the whole team after that the

developers start coding and what

cody's they code so that they can make

the test pass by adding the new code

once you once they know that these are

the test cases that needs to pass or

need to be fulfilled by the code that

they are developing so they start coding

to make those tests pass and the third

step is to refactor the code to pass the

written test so once they write the code

they run it if there are failing tests

they again refactor the code and unless

all the test cases that are written in

TDD approach are passed now TDD uses

following processes so if you that the

process is you write a failing unit test

you make the Unitec test pass and then

repeat this whole process so the test

case is defined by you they are the unit

tests before the actual development

starts and they will be the failing

tests in the first instance once the

developer starts coding he will start

passing those unit tests because there

will be some code to fulfill the

scenarios that has been written and if

there are some failing tests after the

execution he'll repeat the same refactor

process until all the test cases that

are defined in TDD approach are passed

now let's see in the next slide the

whole TDD process cycle so you add the

test cases which are the unit test cases

and in agile projects the whole team so

you mostly tester identifies these test

cases along with the whole team and then

the developer watches these tests that

they are failing and then he writes the

code runs the test again and see how

many tests are passed and how many are

failed and then he refactor the code

until all the test cases are passed and

that cycle keeps going on so there could

be unlike new test cases again added

within the cycle until all the test

cases are passed this cycle continues

adding code refactoring the code and

adding new test cases so this whole

cycle keeps on keeps going on unless all

the test cases are pass now

that's the basic test driven development

cycle and what are the benefits of

test-driven development that in TDD

approach the entire code is covered

under the test as code is written only

after adding the test so because you

write the test cases first so there is

no code which is written the the any or

any code that is written in TDD approach

is upon the test cases so you'd you have

the test case that is already there and

the code is written only to fulfill that

particular test care to pass particular

test case so there the coverage or the

test coverage in TDD approach is very

good and then there are less defects

because you start with the test cases

first so entire code is covered by the

test cases or test scenarios so final

application eventually has less defects

in test-driven development approach so

in this tutorial we'll learn what

test-driven development is and what is

the TDD cycle test-driven development

cycle and some of the benefits of

test-driven development thank you