This document provides an overview of test-driven development (TDD). It defines TDD as a technique for building software by writing tests first before production code. The key aspects of TDD covered include the three laws of TDD, why it is used, the typical TDD process through an LED example, research on its effectiveness, designing code for testability, and best practices. Overall, TDD aims to increase code quality and catch errors early through writing automated tests before code, but requires effort and experience to apply effectively.
Test Driven Development Methodology and Philosophy Vijay Kumbhar
A technique for building software that guides software development by writing tests. This is the philosophy and state of mind that a developer should change and start following TDD
One of the main hindrances to teams being able to respond rapidly to new features are technical problems resulting from bad coding practices, also known as technical debt. Melissa and Brett will cover Agile tools and practices that help development teams write better code and increase maintainability. Topics that will be covered include:
Pair programming
Automated Unit Testing
Refactoring
Test-Driven Development
Agile Architecture
This document discusses test-driven development (TDD) and unit testing. It begins with an introduction to TDD and examples using PHPUnit. It then explores the TDD cycle, common excuses for not using TDD, and pros and cons of TDD. Next, it distinguishes unit testing from TDD and discusses unit testing frameworks like PHPUnit and SimpleTest. Finally, it provides examples of code for a simple game that could be used to learn TDD and unit testing techniques.
Test driven development_continuous_integrationhaochenglee
This document discusses test-driven development (TDD) and continuous integration (CI). It explains that TDD involves writing tests before code to drive the design. The key steps of TDD are design, test, implement, and test again. CI involves integrating code changes frequently, usually daily, to catch errors early. TDD and CI work well together as the tests from TDD can be run automatically through CI to provide rapid feedback. The document provides an overview of how to implement TDD and CI using tools like Jenkins.
This document outlines an agenda for a presentation on Test Driven Development (TDD) best practices. The agenda includes sections on an overview and introduction to TDD, what TDD is and the process, challenges of TDD, learning and best practices for sustaining TDD, frameworks and variations of TDD, and a question and answer period. Some key best practices discussed are writing tests before code, focusing tests on functionality rather than code structure, and establishing governance and training to ensure proper adoption of TDD.
Test driven development : software process Amin Taheri
This presentation is about the software development process focusing On Test-Driven Development (TDD)
This is based on Udemy Unit testing and TDD python.
This presentation contains:
Definition of Software Development Process
■ Domain-Driven Development (DDD)
■ Continuous Integration (CI)
■ Behavior Driven Development (BDD)
■ Extreme Programming (XP) – Pair programming – Standup meetings
■ Test-Driven Development (TDD)
■ Hands-on TDD (Live coding)
Android Test Driven Development & Android Unit Testingmahmoud ramadan
This document discusses test driven development (TDD) using JUnit and Mockito for Android. It defines TDD, explains the benefits which include automated testing and improved code quality. It provides examples of using JUnit for unit testing like parametric testing and test lifecycles. It also explains how to use Mockito to mock dependencies and verify interactions through stubbing and spying. The document emphasizes that TDD leads to more modular, flexible and maintainable code.
Test Driven Development Methodology and Philosophy Vijay Kumbhar
A technique for building software that guides software development by writing tests. This is the philosophy and state of mind that a developer should change and start following TDD
One of the main hindrances to teams being able to respond rapidly to new features are technical problems resulting from bad coding practices, also known as technical debt. Melissa and Brett will cover Agile tools and practices that help development teams write better code and increase maintainability. Topics that will be covered include:
Pair programming
Automated Unit Testing
Refactoring
Test-Driven Development
Agile Architecture
This document discusses test-driven development (TDD) and unit testing. It begins with an introduction to TDD and examples using PHPUnit. It then explores the TDD cycle, common excuses for not using TDD, and pros and cons of TDD. Next, it distinguishes unit testing from TDD and discusses unit testing frameworks like PHPUnit and SimpleTest. Finally, it provides examples of code for a simple game that could be used to learn TDD and unit testing techniques.
Test driven development_continuous_integrationhaochenglee
This document discusses test-driven development (TDD) and continuous integration (CI). It explains that TDD involves writing tests before code to drive the design. The key steps of TDD are design, test, implement, and test again. CI involves integrating code changes frequently, usually daily, to catch errors early. TDD and CI work well together as the tests from TDD can be run automatically through CI to provide rapid feedback. The document provides an overview of how to implement TDD and CI using tools like Jenkins.
This document outlines an agenda for a presentation on Test Driven Development (TDD) best practices. The agenda includes sections on an overview and introduction to TDD, what TDD is and the process, challenges of TDD, learning and best practices for sustaining TDD, frameworks and variations of TDD, and a question and answer period. Some key best practices discussed are writing tests before code, focusing tests on functionality rather than code structure, and establishing governance and training to ensure proper adoption of TDD.
Test driven development : software process Amin Taheri
This presentation is about the software development process focusing On Test-Driven Development (TDD)
This is based on Udemy Unit testing and TDD python.
This presentation contains:
Definition of Software Development Process
■ Domain-Driven Development (DDD)
■ Continuous Integration (CI)
■ Behavior Driven Development (BDD)
■ Extreme Programming (XP) – Pair programming – Standup meetings
■ Test-Driven Development (TDD)
■ Hands-on TDD (Live coding)
Android Test Driven Development & Android Unit Testingmahmoud ramadan
This document discusses test driven development (TDD) using JUnit and Mockito for Android. It defines TDD, explains the benefits which include automated testing and improved code quality. It provides examples of using JUnit for unit testing like parametric testing and test lifecycles. It also explains how to use Mockito to mock dependencies and verify interactions through stubbing and spying. The document emphasizes that TDD leads to more modular, flexible and maintainable code.
Joe Cisar - Everything I Know About TDD - Agile Midwest 2019Jason Tice
The document discusses test-driven development (TDD). TDD is a software development process where test cases are created to specify requirements before code is written to pass those tests. This ensures code meets requirements. Benefits of TDD include fewer bugs due to comprehensive testing, and ability to refactor code without breaking functionality. The document provides examples of different types of tests and outlines best practices for getting started with TDD.
This document provides information about an upcoming presentation on effective unit testing in MuleSoft. The presentation will be given by Josh Erney, a MuleSoft Ambassador with over 5 years of experience developing and architecting MuleSoft solutions. The presentation will focus on 5 key steps for effective unit testing: 1) Understanding the value of unit tests, 2) Asserting code meets interface contracts, 3) Writing testable code, 4) Removing noise from tests, and 5) Prioritizing valuable tests over code coverage. The presenter will provide examples and tips for writing high-quality unit tests that reduce maintenance costs and increase development velocity. Attendees will learn how to identify important tests, write testable code, and focus
Learn how Acceptance Test Driven Development (ATDD) provides the process for capturing detailed requirements as acceptance criteria and turn them into as test cases before development begins using Behavior Driven Development (BDD). The BDD approach and Gherkin format is the language used to create easy to understand and actionable scenarios that map from the functional level to the components and units. We will discuss the different approaches to TDD including a realistic approach leveraging BDD to a purest standpoint where TDD use the tests to drive the design of the application. Finally understand how the tools in Visual Studio and Team foundation Server to support BDD such as SpecFlow (Cucumber in .NET), Refactoring tools, and Test Cases in MTM.
TDD and Simple Design Workshop - Session 1 - March 2019Paulo Clavijo
The document discusses test-driven development (TDD) and simple design. It introduces TDD and some of its core practices, including test-driven development, simple design, refactoring, and pair programming. It provides an agenda for a workshop that will cover these topics over three sessions, including extreme programming (XP), the four elements of simple design, test doubles, outside-in TDD, and SOLID principles. The workshop aims to communicate best practices for using technical practices to succeed with agile development.
Test Driven Development (TDD) is an approach where test cases are written before functional code to think about how components should work. It follows the principles of Red-Green-Refactor, writing a test (Red), then the functional code to pass the test (Green), then refactoring the code. TDD leads to well-designed, loosely coupled code with full test coverage that is easy to maintain and refactor with confidence in changes. While it may initially take longer, TDD finds bugs earlier and reduces bugs by 45-90%, saving significant time versus fixing issues late in development.
Test-driven development (TDD) is a process where test cases are created to validate requirements before functional code is written. The primary goals of TDD are to help specify requirements and design and to produce clean, bug-free code through a short development cycle of writing tests then code to pass those tests. Good unit tests for TDD should run fast, isolate dependencies, clearly define their scope, not require special setup, and clearly indicate their intention. In Golang, the testing package and go test command provide tools for writing and running tests, and go test can measure test coverage.
TDD is a software development practice where tests are written before production code to define requirements. It follows three rules: 1) Write a test that fails without production code. 2) Write just enough production code to pass the test. 3) Refactor code without changing external behavior. This ensures code is properly tested and reduces bugs through frequent integration and refactoring enabled by the test suite. TDD results in testable, loosely coupled code and faster delivery times.
Test driven development - Zombie proof your codePascal Larocque
This document discusses test driven development and how to write testable code. It recommends writing tests before writing code to prevent "zombie code" that is hard to maintain and change. Specific tips provided include using dependency injection, following SOLID principles to separate concerns, and writing fast, isolated tests using tools like PHPUnit and PHPSpec. Continuous integration is also recommended to prevent technical debt from accumulating.
Understanding TDD - theory, practice, techniques and tips.Malinda Kapuruge
My talk at the Swinburne University on 09/10/2019. Presented to students as part of the series, Development Projects - Tools and Practices.
Level: Beginner
This document discusses test-driven development (TDD), a software development technique where test cases are written before implementation code. TDD involves writing a failing test case, then code to pass the test, and refactoring code as needed. Key principles are writing tests first, running tests frequently, and making code changes in small iterative steps. TDD aims to increase code quality and reduce bugs by fully testing code in short cycles.
This document provides an overview of test driven development (TDD). It discusses unit testing, refactoring, and the TDD process. The TDD process involves writing a failing test first, then code to pass the test, and refactoring code as needed. Adopting TDD practices can improve code quality and catch defects earlier. Examples are provided to illustrate applying TDD to a login feature.
Discover why unit testing is such an important practice in software development and learn about Test Driven Development, mocking and other code testing practices in .Net
Test Driven Development (TDD) is a software development technique where unit tests are written before functional code to verify functionality. The TDD process follows a "Red, Green, Refactor" cycle where tests fail initially ("Red"), code is written to pass tests ("Green"), and code is refactored to improve design. While TDD may improve code quality and catch errors earlier, studies have shown mixed results on productivity and quality improvements. Adopting TDD fully can be challenging in practice due to issues like incomplete test coverage and resistance to change.
The original promise of TDD was that it would assist in guiding the development of clean code, but it often ends up polluting our architecture with excessive composition, is expensive to write, and becomes an obstacle to change, not an aid to refactoring. In this talk, we look at the fallacies of TDD and learn about the key principles that we should be following for mastery of this practice. This talk is intended for those who have been practicing TDD, or who have tried TDD and given up because of shortcomings in the approach they were taught.
Test driven development involves writing tests before writing code to make the tests pass. This ensures code is built to satisfy explicit requirements. The TDD process is: write a failing test, write code to pass the test, refactor code. This improves quality by preventing defects and ensuring code is maintainable through extensive automated testing. Acceptance TDD applies this process on a system level to build the right functionality.
This document discusses unit testing and its benefits. It begins by outlining some questions about unit testing, then compares unit tests to UI tests. Unit tests are faster, test individual functions, and make code easier to change and refactor. The document provides an example of unit testing a password validation function in PHP Laravel. It discusses that while test coverage is a quality metric, high coverage alone does not guarantee high quality. It argues that internal quality through practices like unit testing does not require tradeoffs with development speed, and can actually improve productivity by reducing unnecessary tasks and lead time. Maintaining clean code through practices like unit testing is important for both quality and speed.
A Study: The Analysis of Test Driven Development And Design Driven TestEditor IJMTER
There are various types of testing methods. In this paper, we have discussed TDD and
DDT. Test driven development method is a type of agile methodology. In this method, test drives the
design. Basically, TDD is a unit testing. It is a test-first approach method[15]. This method can be a
never ending process, because we are writing the test first, then writing the code to make the test
pass. If test fails then again we will change the code and then we will test again. Using this method,
defect rate can be reduced to 50%. But DDT cannot be a never ending process, because we design
first, then we implement that design any way. TDD is more complex to implement, while DDT is a
bit easier
This document discusses Test-Driven Development (TDD). It defines TDD as writing unit tests before writing any production code. TDD helps ensure code is consistently refactored for better design. The document outlines the TDD process of writing a test, seeing it fail, writing code to pass the test, then refactoring. It discusses using TDD with legacy code by refactoring code to be testable. Sample unit tests are provided to demonstrate testing default constructor values. Benefits of TDD include better code design, earlier defect detection, and fewer defects in production releases.
This document provides an overview of test driven development (TDD), including what TDD is, an example unit test, the TDD process, benefits of TDD such as more maintainable code and fewer bugs, and resources for learning and practicing TDD such as books and training courses. TDD involves writing automated tests before implementation code to help ensure code quality and catch errors early. The process involves writing a test, seeing it fail, then writing just enough code to make it pass and refactoring as needed.
Project Management: The Role of Project Dashboards.pdfKarya Keeper
Project management is a crucial aspect of any organization, ensuring that projects are completed efficiently and effectively. One of the key tools used in project management is the project dashboard, which provides a comprehensive view of project progress and performance. In this article, we will explore the role of project dashboards in project management, highlighting their key features and benefits.
Joe Cisar - Everything I Know About TDD - Agile Midwest 2019Jason Tice
The document discusses test-driven development (TDD). TDD is a software development process where test cases are created to specify requirements before code is written to pass those tests. This ensures code meets requirements. Benefits of TDD include fewer bugs due to comprehensive testing, and ability to refactor code without breaking functionality. The document provides examples of different types of tests and outlines best practices for getting started with TDD.
This document provides information about an upcoming presentation on effective unit testing in MuleSoft. The presentation will be given by Josh Erney, a MuleSoft Ambassador with over 5 years of experience developing and architecting MuleSoft solutions. The presentation will focus on 5 key steps for effective unit testing: 1) Understanding the value of unit tests, 2) Asserting code meets interface contracts, 3) Writing testable code, 4) Removing noise from tests, and 5) Prioritizing valuable tests over code coverage. The presenter will provide examples and tips for writing high-quality unit tests that reduce maintenance costs and increase development velocity. Attendees will learn how to identify important tests, write testable code, and focus
Learn how Acceptance Test Driven Development (ATDD) provides the process for capturing detailed requirements as acceptance criteria and turn them into as test cases before development begins using Behavior Driven Development (BDD). The BDD approach and Gherkin format is the language used to create easy to understand and actionable scenarios that map from the functional level to the components and units. We will discuss the different approaches to TDD including a realistic approach leveraging BDD to a purest standpoint where TDD use the tests to drive the design of the application. Finally understand how the tools in Visual Studio and Team foundation Server to support BDD such as SpecFlow (Cucumber in .NET), Refactoring tools, and Test Cases in MTM.
TDD and Simple Design Workshop - Session 1 - March 2019Paulo Clavijo
The document discusses test-driven development (TDD) and simple design. It introduces TDD and some of its core practices, including test-driven development, simple design, refactoring, and pair programming. It provides an agenda for a workshop that will cover these topics over three sessions, including extreme programming (XP), the four elements of simple design, test doubles, outside-in TDD, and SOLID principles. The workshop aims to communicate best practices for using technical practices to succeed with agile development.
Test Driven Development (TDD) is an approach where test cases are written before functional code to think about how components should work. It follows the principles of Red-Green-Refactor, writing a test (Red), then the functional code to pass the test (Green), then refactoring the code. TDD leads to well-designed, loosely coupled code with full test coverage that is easy to maintain and refactor with confidence in changes. While it may initially take longer, TDD finds bugs earlier and reduces bugs by 45-90%, saving significant time versus fixing issues late in development.
Test-driven development (TDD) is a process where test cases are created to validate requirements before functional code is written. The primary goals of TDD are to help specify requirements and design and to produce clean, bug-free code through a short development cycle of writing tests then code to pass those tests. Good unit tests for TDD should run fast, isolate dependencies, clearly define their scope, not require special setup, and clearly indicate their intention. In Golang, the testing package and go test command provide tools for writing and running tests, and go test can measure test coverage.
TDD is a software development practice where tests are written before production code to define requirements. It follows three rules: 1) Write a test that fails without production code. 2) Write just enough production code to pass the test. 3) Refactor code without changing external behavior. This ensures code is properly tested and reduces bugs through frequent integration and refactoring enabled by the test suite. TDD results in testable, loosely coupled code and faster delivery times.
Test driven development - Zombie proof your codePascal Larocque
This document discusses test driven development and how to write testable code. It recommends writing tests before writing code to prevent "zombie code" that is hard to maintain and change. Specific tips provided include using dependency injection, following SOLID principles to separate concerns, and writing fast, isolated tests using tools like PHPUnit and PHPSpec. Continuous integration is also recommended to prevent technical debt from accumulating.
Understanding TDD - theory, practice, techniques and tips.Malinda Kapuruge
My talk at the Swinburne University on 09/10/2019. Presented to students as part of the series, Development Projects - Tools and Practices.
Level: Beginner
This document discusses test-driven development (TDD), a software development technique where test cases are written before implementation code. TDD involves writing a failing test case, then code to pass the test, and refactoring code as needed. Key principles are writing tests first, running tests frequently, and making code changes in small iterative steps. TDD aims to increase code quality and reduce bugs by fully testing code in short cycles.
This document provides an overview of test driven development (TDD). It discusses unit testing, refactoring, and the TDD process. The TDD process involves writing a failing test first, then code to pass the test, and refactoring code as needed. Adopting TDD practices can improve code quality and catch defects earlier. Examples are provided to illustrate applying TDD to a login feature.
Discover why unit testing is such an important practice in software development and learn about Test Driven Development, mocking and other code testing practices in .Net
Test Driven Development (TDD) is a software development technique where unit tests are written before functional code to verify functionality. The TDD process follows a "Red, Green, Refactor" cycle where tests fail initially ("Red"), code is written to pass tests ("Green"), and code is refactored to improve design. While TDD may improve code quality and catch errors earlier, studies have shown mixed results on productivity and quality improvements. Adopting TDD fully can be challenging in practice due to issues like incomplete test coverage and resistance to change.
The original promise of TDD was that it would assist in guiding the development of clean code, but it often ends up polluting our architecture with excessive composition, is expensive to write, and becomes an obstacle to change, not an aid to refactoring. In this talk, we look at the fallacies of TDD and learn about the key principles that we should be following for mastery of this practice. This talk is intended for those who have been practicing TDD, or who have tried TDD and given up because of shortcomings in the approach they were taught.
Test driven development involves writing tests before writing code to make the tests pass. This ensures code is built to satisfy explicit requirements. The TDD process is: write a failing test, write code to pass the test, refactor code. This improves quality by preventing defects and ensuring code is maintainable through extensive automated testing. Acceptance TDD applies this process on a system level to build the right functionality.
This document discusses unit testing and its benefits. It begins by outlining some questions about unit testing, then compares unit tests to UI tests. Unit tests are faster, test individual functions, and make code easier to change and refactor. The document provides an example of unit testing a password validation function in PHP Laravel. It discusses that while test coverage is a quality metric, high coverage alone does not guarantee high quality. It argues that internal quality through practices like unit testing does not require tradeoffs with development speed, and can actually improve productivity by reducing unnecessary tasks and lead time. Maintaining clean code through practices like unit testing is important for both quality and speed.
A Study: The Analysis of Test Driven Development And Design Driven TestEditor IJMTER
There are various types of testing methods. In this paper, we have discussed TDD and
DDT. Test driven development method is a type of agile methodology. In this method, test drives the
design. Basically, TDD is a unit testing. It is a test-first approach method[15]. This method can be a
never ending process, because we are writing the test first, then writing the code to make the test
pass. If test fails then again we will change the code and then we will test again. Using this method,
defect rate can be reduced to 50%. But DDT cannot be a never ending process, because we design
first, then we implement that design any way. TDD is more complex to implement, while DDT is a
bit easier
This document discusses Test-Driven Development (TDD). It defines TDD as writing unit tests before writing any production code. TDD helps ensure code is consistently refactored for better design. The document outlines the TDD process of writing a test, seeing it fail, writing code to pass the test, then refactoring. It discusses using TDD with legacy code by refactoring code to be testable. Sample unit tests are provided to demonstrate testing default constructor values. Benefits of TDD include better code design, earlier defect detection, and fewer defects in production releases.
This document provides an overview of test driven development (TDD), including what TDD is, an example unit test, the TDD process, benefits of TDD such as more maintainable code and fewer bugs, and resources for learning and practicing TDD such as books and training courses. TDD involves writing automated tests before implementation code to help ensure code quality and catch errors early. The process involves writing a test, seeing it fail, then writing just enough code to make it pass and refactoring as needed.
Project Management: The Role of Project Dashboards.pdfKarya Keeper
Project management is a crucial aspect of any organization, ensuring that projects are completed efficiently and effectively. One of the key tools used in project management is the project dashboard, which provides a comprehensive view of project progress and performance. In this article, we will explore the role of project dashboards in project management, highlighting their key features and benefits.
E-commerce Development Services- Hornet DynamicsHornet Dynamics
For any business hoping to succeed in the digital age, having a strong online presence is crucial. We offer Ecommerce Development Services that are customized according to your business requirements and client preferences, enabling you to create a dynamic, safe, and user-friendly online store.
Mobile App Development Company In Noida | Drona InfotechDrona Infotech
Drona Infotech is a premier mobile app development company in Noida, providing cutting-edge solutions for businesses.
Visit Us For : https://www.dronainfotech.com/mobile-application-development/
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This talk explores the challenges of bringing modelling rigour to the business and strategy levels, and talking to your non-technical counterparts in the process.
Preparing Non - Technical Founders for Engaging a Tech AgencyISH Technologies
Preparing non-technical founders before engaging a tech agency is crucial for the success of their projects. It starts with clearly defining their vision and goals, conducting thorough market research, and gaining a basic understanding of relevant technologies. Setting realistic expectations and preparing a detailed project brief are essential steps. Founders should select a tech agency with a proven track record and establish clear communication channels. Additionally, addressing legal and contractual considerations and planning for post-launch support are vital to ensure a smooth and successful collaboration. This preparation empowers non-technical founders to effectively communicate their needs and work seamlessly with their chosen tech agency.Visit our site to get more details about this. Contact us today www.ishtechnologies.com.au
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How do you combine the OpenUI5/SAPUI5 programming model with a design system that makes its controls available as Web Components? Since OpenUI5/SAPUI5 1.120, the framework supports the integration of any Web Components. This makes it possible, for example, to natively embed own Web Components of your design system which are created with Stencil. The integration embeds the Web Components in a way that they can be used naturally in XMLViews, like with standard UI5 controls, and can be bound with data binding. Learn how you can also make use of the Web Components base class in OpenUI5/SAPUI5 to also integrate your Web Components and get inspired by the solution to generate a custom UI5 library providing the Web Components control wrappers for the native ones.
8 Best Automated Android App Testing Tool and Framework in 2024.pdfkalichargn70th171
Regarding mobile operating systems, two major players dominate our thoughts: Android and iPhone. With Android leading the market, software development companies are focused on delivering apps compatible with this OS. Ensuring an app's functionality across various Android devices, OS versions, and hardware specifications is critical, making Android app testing essential.
Measures in SQL (SIGMOD 2024, Santiago, Chile)Julian Hyde
SQL has attained widespread adoption, but Business Intelligence tools still use their own higher level languages based upon a multidimensional paradigm. Composable calculations are what is missing from SQL, and we propose a new kind of column, called a measure, that attaches a calculation to a table. Like regular tables, tables with measures are composable and closed when used in queries.
SQL-with-measures has the power, conciseness and reusability of multidimensional languages but retains SQL semantics. Measure invocations can be expanded in place to simple, clear SQL.
To define the evaluation semantics for measures, we introduce context-sensitive expressions (a way to evaluate multidimensional expressions that is consistent with existing SQL semantics), a concept called evaluation context, and several operations for setting and modifying the evaluation context.
A talk at SIGMOD, June 9–15, 2024, Santiago, Chile
Authors: Julian Hyde (Google) and John Fremlin (Google)
https://doi.org/10.1145/3626246.3653374
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Flutter is a popular open source, cross-platform framework developed by Google. In this webinar we'll explore Flutter and its architecture, delve into the Flutter Embedder and Flutter’s Dart language, discover how to leverage Flutter for embedded device development, learn about Automotive Grade Linux (AGL) and its consortium and understand the rationale behind AGL's choice of Flutter for next-gen IVI systems. Don’t miss this opportunity to discover whether Flutter is right for your project.
Hand Rolled Applicative User ValidationCode KataPhilip Schwarz
Could you use a simple piece of Scala validation code (granted, a very simplistic one too!) that you can rewrite, now and again, to refresh your basic understanding of Applicative operators <*>, <*, *>?
The goal is not to write perfect code showcasing validation, but rather, to provide a small, rough-and ready exercise to reinforce your muscle-memory.
Despite its grandiose-sounding title, this deck consists of just three slides showing the Scala 3 code to be rewritten whenever the details of the operators begin to fade away.
The code is my rough and ready translation of a Haskell user-validation program found in a book called Finding Success (and Failure) in Haskell - Fall in love with applicative functors.
How Can Hiring A Mobile App Development Company Help Your Business Grow?ToXSL Technologies
ToXSL Technologies is an award-winning Mobile App Development Company in Dubai that helps businesses reshape their digital possibilities with custom app services. As a top app development company in Dubai, we offer highly engaging iOS & Android app solutions. https://rb.gy/necdnt
2. Outline
● What is TDD and why use it
● The TDD Process
● Effectiveness of TDD
● Designing for Testability
3. What is Test-Driven Development
“Test-Driven Development (TDD) is a technique for building
software that guides software development by writing tests.”
- Martin Fowler
Design Test Code
Design Code Test
Test-After
Development
Test-Driven Development
4. The Three Laws of TDD
1. You may not write production code unless
you've written a failing test first
2. You may not write more of a unit test than is
sufficient to fail
3. You may not write more production code than
is sufficient to make the failing unit test pass
5. Why Test-Driven Development?
● Instant feedback
○ Faster debugging, more confidence
○ Squash larvae instead of hunting mature bugs
● Better development practices
○ Drive writing testable code
○ Decompose into manageable tasks
● Tests always up-to-date
○ Tests themselves are also tested!
● Increased value of tests as documentation
“Test-first code tends to be more
cohesive and less coupled than code
in which testing isn’t a part of the
intimate coding cycle”
- Kent Beck
6. But!
● We don't have the time or money!
○ Short-term loss, long-term gain
○ Bugs in production are costly
● I am already writing unit tests…
○ Sometimes happy path only
○ In practice fewer total tests
● TDD feels too restricting and unnatural
○ Rules can be adjusted
Initial Investment
Waterfal
l
TDD
Savings
8. The TDD process LED example
● Define a test list
● Add a small failing test
● Implement minimal code
● Make the test pass
● Refactor
9. The TDD process
James W. Grenning - Test Driven Development for Embedded C
● Define a test list
● Add a small failing test
● Implement minimal code
● Make the test pass
● Refactor
10. The TDD process
TEST(LedDriver, TurnOnLedOne)
{
LedDriver_TurnOn(1);
TEST_ASSERT_EQUAL_HEX16(1,virtualLeds);
}
void LedDriver_TurnOn(int ledNumber)
{
}
1 Tests 1 Failures 0 Ignored
● Define a test list
● Add a small failing test
● Implement minimal code
● Make the test pass
● Refactor
11. The TDD process
TEST(LedDriver, TurnOnLedOne)
{
LedDriver_TurnOn(1);
TEST_ASSERT_EQUAL_HEX16(1,virtualLeds);
}
void LedDriver_TurnOn(int ledNumber)
{
*ledsAddress = 1;
}
● Define a test list
● Add a small failing test
● Implement minimal code
● Make the test pass
● Refactor
12. The TDD process
TEST(LedDriver, TurnOnLedOne)
{
LedDriver_TurnOn(1);
TEST_ASSERT_EQUAL_HEX16(1,virtualLeds);
}
void LedDriver_TurnOn(int ledNumber)
{
*ledsAddress = 1;
}
1 Tests 0 Failures 0 Ignored
● Define a test list
● Add a small failing test
● Implement minimal code
● Make the test pass
● Refactor
13. The TDD process
TEST(LedDriver, TurnOnMultipleLeds)
{
LedDriver_TurnOn(8);
LedDriver_TurnOn(9);
TEST_ASSERT_EQUAL_HEX16(0x180,virtualLeds);
}
void LedDriver_TurnOn(int ledNumber)
{
*ledsAddress = 1;
}
2 Tests 1 Failures 0 Ignored
● Define a test list
● Add a small failing test
● Implement minimal code
● Make the test pass
● Refactor
14. The TDD process
TEST(LedDriver, TurnOnMultipleLeds)
{
LedDriver_TurnOn(8);
LedDriver_TurnOn(9);
TEST_ASSERT_EQUAL_HEX16(0x180,virtualLeds);
}
void LedDriver_TurnOn(int ledNumber)
{
*ledsAddress |= 1 << (ledNumber - 1);
}
● Define a test list
● Add a small failing test
● Implement minimal code
● Make the test pass
● Refactor
15. The TDD process
TEST(LedDriver, TurnOnMultipleLeds)
{
LedDriver_TurnOn(8);
LedDriver_TurnOn(9);
TEST_ASSERT_EQUAL_HEX16(0x180,virtualLeds);
}
void LedDriver_TurnOn(int ledNumber)
{
*ledsAddress |= 1 << (ledNumber - 1);
}
2 Tests 0 Failures 0 Ignored
● Define a test list
● Add a small failing test
● Implement minimal code
● Make the test pass
● Refactor
16. The TDD process
TEST(LedDriver, TurnOnMultipleLeds)
{
LedDriver_TurnOn(8);
LedDriver_TurnOn(9);
TEST_ASSERT_EQUAL_HEX16(0x180,virtualLeds);
}
void LedDriver_TurnOn(int ledNumber)
{
*ledsAddress |= LedNumberToBit(ledNumber);
}
● Define a test list
● Add a small failing test
● Implement minimal code
● Make the test pass
● Refactor
18. What do research studies say?
● Microsoft and IBM Case study
○ 15-35% initial time increase, 40-90% less defects
● George and Williams, Professional Pair programmers Java bowling game
○ 16% slower, 18% more test cases
● Choma, Study on developers perception with ~10 years of experience
○ 96% → reduces debugging effort
○ 92% → higher quality code
○ 71% → noticeably effective
https://www.microsoft.com/en-us/research/wp-content/uploads/2009/10/Realizing-Quality-Improvement-
Through-Test-Driven-Development-Results-and-Experiences-of-Four-Industrial-Teams-nagappan_tdd.pdf
https://dl.acm.org/doi/10.1145/952532.952753
https://link.springer.com/chapter/10.1007/978-3-319-91602-6_5
Notable Studies
19. What do research studies say?
● Internal Quality:
● Weighted methods per class, Depth of inheritance tree, Number of children,
Coupling between objects, Lack of cohesion in methods
● External Quality:
Test cases passed, Defect density, Defects per test, Effort required to fix
defects, Change density, Percentage of preventative changes
● Productivity: Amount of code/features produced per development effort
● Test Quality: Test density, Test coverage, Test productivity
Metrics
https://www.researchgate.net/publication/258126622_How_Effective_is_Test_Driven_Development
https://arxiv.org/pdf/1711.05082.pdf
20. What do research studies say?
● Research results lack a definitive conclusion
● Increased test coverage, decreased defect density
● Productivity: inconclusive, short-term loss long-term gain?
Industrial Semi-Industrial Academic
Internal Quality o o o
External Quality + + o
Test Quality o + +
Productivity — o +
Results
https://www.researchgate.net/publication/258126622_How_Effective_is_Test_Driven_Development https://arxiv.org/pdf/1711.05082.pdf
Metric
Field
21. ● Initial productivity loss → better external quality
● TDD developers get faster over time
● Confidence increases due to broad test coverage
● TDD requires monitoring adjusting dosage accordingly
“somewhere around the 2-years in the mark, something magical started to happen:
I started coding faster with unit tests than I ever did without them” - Eric Elliott
Takeaways
What do research studies say?
● TDD creates tests as documentation
○ Shorten onboarding and handoffs?
○ Increased resilience to losing knowledgeable people?
● Effect on job satisfaction and developer retention?
22. What do research studies say?
● Metric definitions lack detail or unrepresentative
● Limited scope and size of projects
● Different language, environment, and domain context
● Difficult to measure TDD adherence
● Differences in programmer skill levels
Issues
"TDD improves code quality"
source: https://ieeexplore.ieee.org/document/5463691
23. ● Not a panacea nor failproof
● Steep learning curve, adapt mindest
● Can be difficult to predict course
● False sense of security
● Difficult to use in some situations
Limitations
“TDD helps with, but does not guarantee,
good design and good code. Skill, talent,
and expertise remain necessary”
- Esko Luontola
Possible variation:
● Code up fast prototypes for exploration to be thrown away (Spike)
● Write down important test cases and observations
25. The TDD process
Real code has dependencies → break dependencies:
● Hardware independence
○ Stand-in for expensive hardware
● Inject difficult to produce inputs
○ Network failure
● Speed up a slow collaborator
○ Database
● Replace something under development
○ Software library
Designing for Testability External Dependencies
"Pull the plug now, Harry!"
26. The TDD process
Test Doubles:
● Dummy, Stub, Spy, Mock, Fake
● Allow us to independently test application code
Designing for Testability External Dependencies
27. The TDD process
Test Doubles
Designing for Testability External Dependencies
Simple
Complex
Dummy Never called, allows program to compile
Stub Returns a value as directed by test case
Spy Returns a value and verifies parameters passed
Mock Verifies function calls, call order, and parameters passed
Fake Partial implementation of a real component
28. The TDD process
● Prescribe which calls to expect, then execute process
Designing for Testability Mocking
TEST(Flash, WriteSucceeds_ReadyImmediately)
{
MockIO_Expect_Write(CommandRegister, ProgramCommand);
MockIO_Expect_Write(address, data);
MockIO_Expect_ReadThenReturn(StatusRegister, ReadyBit);
MockIO_Expect_ReadThenReturn(address, data);
result = Flash_Write(address, data);
LONGS_EQUAL(FLASH_SUCCESS, result);
}
29. The TDD process
● Mocks should be simple
○ Complex mocks hard to read and maintain
● Heavy mocking can lead to brittle tests
○ When implementation changes tests need update
● Mocks can lead to overconfidence
○ Mocks may mask integration issues
Designing for Testability Mocking Challenges
30. The TDD process
● SOLID principles keep modules flexible and testable
○ Dependency Inversion, Open-Closed, Liskov Substitution
● LightController should not know about concrete drivers
Designing for Testability Interfaces
31. The TDD process
● Test-drive the interface before the internals
● Tests should test a single concept
● Focus on tests that increase confidence
● Legacy code: add tests before modification
TDD Best Practices
32. The TDD process
Acceptance Test-Driven Development
● Collaboratively define acceptance tests
● Focus on capturing the business requirements
TDD Extensions
Behaviour-Driven Development
● Define system behaviour from perspective of stakeholders
● Given-When-Then
Extend TDD by involving different stakeholders
TEST(LightScheduler, ScheduleOffWeekendAndItsSaturdayAndItsTime)
checkLightState(lightNumber, LIGHT_OFF);
then
33. The Future of TDD with AI?
● Use tests to communicate system requirements to AI
● Allow non-technical people to specify desired behavior
● The Two Disks Parable
https://drpicox.medium.com/the-two-disks-parable-ac1a16803c58
34. In Summary
● TDD has potential but requires monitoring
● Reliant on developer experience and motivation
● No clear consensus regarding internal quality
● Better suited for some contexts than others
Also known as TDD
We're going to discuss what it is and what it is not,
and also what it's good at and what it's not good at
roughly divided into 4 section
We start with the general introduction
what it is and why should care
Quickly go through TDD process with an example as a refresher
After that we'll look at some empirical studies on TDD and its effectiveness
Lastly, I will go over how some more advanced topics regarding design and testability
So, What is test-driven development
Martin Fowler gave following definition states that
TDD is a method for developing software, NOT just testing software,
which is guided by writing tests
In the traditional test-after approach implementation first
but with TDD we write our tests before the implementation
so already test in place that tell you what the implementation should do
Proper TDD adheres to the following three laws.
1
2
this last point is where a lot of developers get disturbed
sometimes this means writing an implementation that you know is wrong
but it still allows you to pass the current test
and your future tests will have to make sure you eventually come to the correct implementation
TODO: Image of crane building here
TDD is really about steady, incremental progress.
Whereas in test-after we might implement and test a big chunk of work at once, in TDD we do it in small but confident steps.
TDD reduces the likelihood that we need to go back and fix things and also makes it easier to fix things, since we know the last change broke something.
Now that we have a definition for TDD, let's look at why you would use it in the first place
Just to be clear, this presentation is not going to be a pure advertisement for TDD. Rather, I want to discuss the pros and cons
One of the main benefits is Instant feedback: we want our feedback loops to be a short as possible
Running test frequently, catch defects early, last change, more confidence as tests are passing
If you write a big chunk of implementation first, it can be hard to properly test all of your code
By writing the tests first you are driven to write testable code from the start, instead of trying to squeeze them in later
It also encourages decomposing the problem into manageable tasks, one small test at a time
Safer refactoring as you have already tests in place
While non-TDD tests can also serve as documentation
TDD tests may do a better job at capturing the original intentions
When you go into new code you don't know much about implementation yet
Non-TDD test may focus more on validating the code rather than specifying its requirements.
These are some common objections to TDD
Most and foremost, we don't have the time or money for TDD
With TDD you have an initial investment,
but this should eventually pay out in the long run because of less debugging
And bugs in production can be very costly
Another argument is, I am already writing unit tests!
Tests are usually different with test after, Often just the happy path is tested
Also, in practice test-after usually ends up with less tests than TDD
After the product has been implemented and shipped it's unlikely unit tests are going to be written
For some people TDD feels to restricting,
but like any other tool, there is some leeway and it's okay to adjust the granularity a bit to your liking
Later on we're going to discuss the actual effects and costs
now, A quick refresher on the TDD process
For this example we have a an array of LEDs
and we want to implement some driver functionality with TDD
The first step is to define a test list
With all the relevant tests that you can think of currently
These can also be deduced from a requirement specification
May evolve as we implement features
By failing the test first we also confirm that the test doesn't give a false positive, thus we test the test
These simple implementations test our tests.
Watching the test case fail shows that the test can detect a wrong result.
EXTRA:
In essence, we’re closing a vice around the code under test,
holding the behavior steady (see the sidebar on the following page).
Don’t worry, the production code won’t be hard-coded and incomplete
for long. As soon as you need to turn on a different LED, the hard-coded value will have to go.
The real implementation is not much more diffi-
cult, but I ask you to resist the temptation to put in more code than is
needed by the current test. We’re evolving the design. The problem with
adding more code than the current tests require is that you probably
won’t write all the tests you need to keep future, and present, bugs out
of the code.
Adding code before it is needed by the tests adds complexity. Sometimes
you will be wrong about the need, resulting in carrying the complexity
unnecessarily.
Also, there is no end to the thinking “I will need it.”
Where should you stop? In practicing TDD, we stop when the code is
not needed by the current tests.
Loose ends are cataloged in the test list.
TDD is structured procrastination. Put off writing the right production
code until the tests force us to. Implementation completeness, the ulti-
mate objective, is reached only after all the correct tests are in place.
Hard-coding the right answer shows that the test case can detect the right result.
The test is right and valuable, even though the production code is incomplete.
The problem with adding more code than the current tests require
is that you probably won’t write all the tests you need to keep future, and present, bugs out of the code.
In this simple example it may be obvious, but for more complex cases it may not be
Adding code before it is needed by the tests adds complexity.
Sometimes you will be wrong about the need, resulting in carrying the complexity unnecessarily.
EXTRA:
In essence, we’re closing a vice around the code under test,
holding the behavior steady (see the sidebar on the following page).
Don’t worry, the production code won’t be hard-coded and incomplete
for long. As soon as you need to turn on a different LED, the hard-coded value will have to go.
The real implementation is not much more diffi-
cult, but I ask you to resist the temptation to put in more code than is
needed by the current test. We’re evolving the design.
The problem with adding more code than the current tests require is that you probably
won’t write all the tests you need to keep future, and present, bugs out
of the code.
Adding code before it is needed by the tests adds complexity. Sometimes
you will be wrong about the need, resulting in carrying the complexity
unnecessarily.
Also, there is no end to the thinking “I will need it.”
Where should you stop? In practicing TDD, we stop when the code is
not needed by the current tests.
Loose ends are cataloged in the test list.
TDD is structured procrastination. Put off writing the right production
code until the tests force us to. Implementation completeness, the ulti-
mate objective, is reached only after all the correct tests are in place.
Not much to refactor yet, so add next test
For the next tests we turn on multiple random LEDS
And now we see that our previous implementation was wrong
At this point, the easiest way is simply to add the correct implementation
The Tests Are Right
With the implementation being incomplete, you might think that noth-
ing is being tested. Big deal! The test makes sure that a variable is set
to one!
Try to think about it a different way. The tests are right! They are a
very valuable by-product of TDD. These simple implementations test
our tests. Watching the test case fail shows that the test can detect a
wrong result. Hard-coding the right answer shows that the test case can
detect the right result. The test is right and valuable, even though the
production code is incomplete. Later, as the implementation evolves,
these seemingly trivial tests will test important behavior and boundary
conditions. In essence, we’re closing a vice around the code under test,
holding the behavior steady (see the sidebar on the following page).
Don’t worry, the production code won’t be hard-coded and incomplete
for long. As soon as you need to turn on a different LED, the hard-coded value will have to go. The real implementation is not much more diffi-
cult, but I ask you to resist the temptation to put in more code than is
needed by the current test. We’re evolving the design. The problem with
adding more code than the current tests require is that you probably
won’t write all the tests you need to keep future, and present, bugs out
of the code.
Adding code before it is needed by the tests adds complexity. Sometimes
you will be wrong about the need, resulting in carrying the complexity
unnecessarily. Also, there is no end to the thinking “I will need it.”
Where should you stop? In practicing TDD, we stop when the code is
not needed by the current tests. Loose ends are cataloged in the test
list.
TDD is structured procrastination. Put off writing the right production
code until the tests force us to. Implementation completeness, the ulti-
mate objective, is reached only after all the correct tests are in place.
And only when the tests pass do we refactor, so we add a helper function to clean up the code
Alright, now that we all know what TDD entails, I want to discuss what research has to say about TDD and its effectiveness
First just quickly a couple of notable studies
Microsoft and IBM did a case study with multiple developments teams
Development time increased somewhat (may be due to initial cost)
but significantly less defects
microsoft ibm teams agreed: more time, but offset by less bugs which means less time
Another study by George and Williams had Professional pair programmers develop bowling game
where the control group used waterfall
Their results showed again lower development but more tests cases
And Choma did research focusing on the developer's perception of TDD
with on average 10 years experience
And overall the developers were quite positive towards TDD
Maybe before looking at more results, maybe it is good to look at some metrics
We have the internal quality which mostly relates to the intrinsic quality of the software itself
as defined by some common measures such as
Then we have external quality which says more about the performance and output of the process
How much time and effort did it take
And lastly test quality with metrics such as ..
Here I have aggregate the results of two comparative studies which each compared several different studies on TDD
Where the four metrics are evaluated based on the environment
We have industrial,
we have semi-industrial, which involves either professional in a controlled setting or students in a industrial setting
and then we have academic experiments
There is no obvious consensus in the research
However, test coverage and defect density were fairly consistent over all studies
When it comes to productivity the results are quite inconclusive
it's hard to say something over the very long-term
So mainly there seems to be an initial productivity loss in exchange for better external quality
TDD is really something you have to learn:
Our findings suggest, after overcoming initial difficulties: understand where to start, how to create a test for a feature that does not yet exist,
participants gain greater confidence to implement new features and make changes due to broad test coverage.
actionable advice, carefully monitoring, increasing or decreasing the dosage accordingly
Erick Elliot, author of the book 'composing software', stated that after a magical 2-year mark he started writing faster with unit tests
Then there are a few open questions which have not been studied yet as they are hard to measure but might still play a role
For example, TDD tests may shorten developer onboarding or codebase handoffs?
And lastly,
There are definitely some issues with the conducted research works on TDD
metrics used for describing the findings have not been either defined in detail or lack the quality attribute they should be presenting.
Another problem: small scope of many experiments consisted of small tasks
Different studies used different languages..
The environment and domain context not always specified
And it is also difficult to measure how well developers are following the TDD rules,
which has a big impact on how effective TDD is
Much of the inconsistency likely can be attributed to internal factors not fully described in the TDD trials.
Thus, TDD is bound to remain a controversial topic of debate and research.
TDD definitely has a number of limiations
First, TDD is not a panacea nor failproof,
it still relies a lot on skill and experience of the developer
TDD also has a steep learning curve and often requires developer to adapt a different mindset
Many experienced developers have a mental model of the system they are building, TDD might interfere with this
Can be difficult to predict course, more costly to throw away all tests when wrong, planning ahead too much
False sense of security, if the tests are not sound then test coverage has little value
Can be difficult to use in situations like GUIs, Relational Databases, Web Service
Alright, now let's look at how we can make TDD more effective and also deal with real-world dependencies
In the real world, our code often has external dependencies
Hardware independence: especially useful for embedded system where your board may not have arrived yet or you have limited access to hardware
It also allows us to inject inputs which are difficult to produce
For example if we want to simulate a network failure, we could ask our colleague to pull the plug at a very specific moment
However, this is hardly reproducible and can take a lot of time
Also may want to break dependance on a slow collaborator as the speed of our tests is important
we want our tests to run often and run fast
Lastly, you may want to replace something
In order to break external dependencies we can use test doubles
We can replace our dependent-on-components with test doubles
This allows us to independently test the application code without relying on the any dependencies
There are some different definitions of test doubles going around but I am going to stick with these which are roughly ordered in terms of increasing complexity.
A stub is a very simple entry point that returns a value
Stub: e.g. last thrown exception
Fake: e.g. in-memory database
Complex mocks hard to read and maintain
Test setup becomes more complex
If the tests are heavily coupled to the tests, then tests need to be updated often
It's possible that mocks are hiding intergration issues
integration tests should still be included
With the former implementation on the left, every time we want to add a new driver we need to modify the light controller
But if we use an interface to decouple the lightcontroller from actual driver implementations, then it becomes easier to add new drivers in the future
Legacy code:
• Test-drive new code.
• Add tests to legacy code before modification.
• Test-drive changes to legacy code.
No ramble-on tests
we can test all numbers from 1 to 100 but gives little value
There are two variants with both extend TDD by putting more emphasis on involving different stakeholder such as customers, business analysts, testers
in ATDD developers and stakeholders define acceptance tests together
in BDD, the focus is more on the system behaviour from the stakeholders' pespective
Given that the schedule is turned off for the weekend
And when it's saturday
And when it's normally time to turn on the lights
Then lights should remain, because it's weekend
Use tests to tweak behaviour
TESTS:
TDD. We wrote tests first, and tests created our code. Our code exists because of these tests, and we can repeat the process.
CODE:
But the code would be different. Uhm. Better? The second time that I write the code, I do it better. Let’s crash the CODE and let TESTS survive.
And while there is no clear consensus regarding internal quality, research does suggest several benefits of TDD including a decreased defect rate
In the end, we should keep in mind that TDD is better suited for some contexts than others