Test-driven development (TDD) promotes the writing of tests prior to writing the code that is
being tested. This allows you to focus on your interface and what you expect from your code
prior to focusing on its particular implementation.
The testing components for implementing a test-driven development plan are known as unit
tests.
Test-driven software development technique requires that an automated unit test, defining requirements of the code, is written before each aspect of the code itself. These tests contain assertions that are either true or false.
In test-driven development, each feature begins with writing a test, so for each method, the developer should have to write a unit tests related case. Every method will have more than one test case depending on the complexity of the method signature.
Test-driven development gives developers the confidence to make changes to the system,
because they know that the tests will tell them if they have broken anything and where in the
application the break occurred. This is one of the most effective feedback mechanisms that
the development team can have for ensuring stability and high quality.
Another advantage to test-driven development is that it assists in keeping the code simple.
When developers take a code-first approach to development, they have a tendency to
design as they code, without having a clear picture as to what they want to achieve. They
basically let the creative process lead them to a design while they are coding. This often does
not result in the most straightforward solutions. In fact, in many cases, it results in an overly
complicated design. Test-driven development forces developers to think about the outcome of
what they are developing, and then simply code until the test passes, which leads to a simpler
design. This is called development by intention.
Best practices of using TDD:
1. Write the test first, then the code.
Reason: This ensures that you write testable code and that every line of code gets tests written for it.
being tested. This allows you to focus on your interface and what you expect from your code
prior to focusing on its particular implementation.
The testing components for implementing a test-driven development plan are known as unit
tests.
Test-driven software development technique requires that an automated unit test, defining requirements of the code, is written before each aspect of the code itself. These tests contain assertions that are either true or false.
In test-driven development, each feature begins with writing a test, so for each method, the developer should have to write a unit tests related case. Every method will have more than one test case depending on the complexity of the method signature.
Test-driven development gives developers the confidence to make changes to the system,
because they know that the tests will tell them if they have broken anything and where in the
application the break occurred. This is one of the most effective feedback mechanisms that
the development team can have for ensuring stability and high quality.
Another advantage to test-driven development is that it assists in keeping the code simple.
When developers take a code-first approach to development, they have a tendency to
design as they code, without having a clear picture as to what they want to achieve. They
basically let the creative process lead them to a design while they are coding. This often does
not result in the most straightforward solutions. In fact, in many cases, it results in an overly
complicated design. Test-driven development forces developers to think about the outcome of
what they are developing, and then simply code until the test passes, which leads to a simpler
design. This is called development by intention.
Best practices of using TDD:
1. Write the test first, then the code.
Reason: This ensures that you write testable code and that every line of code gets tests written for it.
2. Design classes using dependency injection.
Reason: You cannot mock or test what cannot be seen.
3. Separate UI code from its behavior using Model-View-Controller or Model-View-Presenter.
Reason: Allows the business logic to be tested while the parts that can't be tested (the UI) is minimized.
4. Do not write static methods or classes.
Reason: Static methods are difficult or impossible to isolate and Rhino Mocks is unable to mock them.
5. Program off interfaces, not classes.
Reason: Interfaces can be easily mocked using Rhino Mocks and other mocking frameworks.
6. Isolate external dependencies.
Reason: Unresolved external dependencies cannot be tested.
Test-Driven Development is a software development technique consisting of short iterations where new test cases covering the desired improvement or new functionality are written first, then the production code necessary to pass the tests is implemented, and finally the software is refactored to accommodate the changes.
Requires test automation
"Keep It Simple, Stupid" (KISS [^]) principle
"You Ain't Gonna Need It" (YAGNI [^]) principle
"Fake it, till you make it" principle
Requires techniques, such as discussion and code reviews for example, to ensure not only that the correct features are implemented, but that the resulting code uses acceptable styles.
Test-Driven Development is a software development technique consisting of short iterations where new test cases covering the desired improvement or new functionality are written first, then the production code necessary to pass the tests is implemented, and finally the software is refactored to accommodate the changes.
Requires test automation
"Keep It Simple, Stupid" (KISS [^]) principle
"You Ain't Gonna Need It" (YAGNI [^]) principle
"Fake it, till you make it" principle
Requires techniques, such as discussion and code reviews for example, to ensure not only that the correct features are implemented, but that the resulting code uses acceptable styles.
What are three Stages of TDD:
1. Red - Create a test case which is failing.
2. Green - Write minimal code to get the test pass.
3. Refactor - Improve the code to make it better but without changing the behavior.
TDD Benefits:
1. Clear expectations (clear flow) of the code.
2. Safety net for future changes
3. Supports continuous integration
Why TDD is more fit in Agile ?
Agile is an iterative development methodology where the term "Continous improvement" very well coined. Agile says that contnous improvement is the goal of the each iteration.
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