Test-driven development

“Test-driven development” is a style of programming in which three activities are blend closely: coding, testing, and design. In other words, the concept of TDD is to write and rectify the failed tests before writing new code (before development). Doing this helps to avoid duplication of code.

TDD cycle defines:

• Firstly, write a test
• Secondly, make it run.
• After that, change code to make it right
• Lastly, repeat the process.

Expected Benefits: Test-driven development

• First things first, Test-driven development offers more than the validation of correctness. That is to say, it also drives the design of a program. Moreover, this benefit is compatible to design by contract as it approaches code through test cases and not through mathematical assertions.
• Secondly, Test-driven development offers the ability to take small steps when necessary. It allows a programmer to focus on the task at hand as the first goal is to make the test pass. Further, this gives the programming team, a certain level of confidence.
• Lastly, TDD often leads to a more flexible code. This is because the methodology requires the developers to think of the software in terms of small units so as to write, test and integrate them together.

Possible Limitations: TDD

• Firstly, Test-driven development doesn’t perform sufficient testing in certain situations. In other words, TTD doesn’t work better where full functional tests are required to determine success or failure, due to extensive use of unit tests.
• In addition, unit tests created in a test-driven development environment are typically the creation of the developer who is writing the code being tested. Therefore, the tests may share blind spots with the code.
• Writing and maintaining an excessive number of tests is a time-consuming process. Moreover, more-flexible modules (with limited tests) might accept new requirements without the need for changing the tests.

Test-Driven Development Cycle

Step 1 – Add a test

Firstly, in test-driven development, each new feature begins with test writing. In other words, you have to write a test that defines a function or its improvements, along with the sufficiency.  However, the developer must clearly comprehend the feature’s requirements. Further, it can be a revamp of an existing test.

Step 2 – Run all tests and see if the new test fails

Secondly, this validates that the test harness is working correctly and indicates that the new test does not pass without requiring new code. In addition, the step increases the developer’s confidence.

Sep 3 – Write the code

After that, your next step is to write some code to pass the test. At this point, the only reason to write the code is to pass the exam.

Step 4 – Run tests

Further, if all test cases pass, the programmer can be confident that the new code meets the test requirements, and does not break or degrade any existing features. If they do not, the new code must be adjusted until they do.

Step 5 – Refactor code

Lastly, the growing code base requires regular cleaning during test-driven development. Duplication requires removal. However, object, class, module, variable and method names should clearly represent their current purpose and use, as extra functionality is added

Repeat – If you wish to start with another new test, the cycle is then repeated to push forward the functionality. Moreover, the size of the steps should always be small. If new code does not speedily satisfy a new test, then the programmer should undo in preference to excessive rectification.

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