Explain Test-Driven Development Cycle?

Test driven development or TDD is considered to one of the most effective as well as efficient software development methodology or process that is often cited under the category of the agile software development processes.

The term “test driven development” is self justifying as one make out from the term itself that it is driven by the tests. Actually, the test driven development process is wholly based up on the repetition process of the several development cycles that are shorter than the usual development cycles. 

This whole article is dedicated to the discussion regarding the test driven development cycle. 

What are the steps in TDD process?

Test driven development process involves the below mentioned steps:

1. First step involves the creation of an automatic test case that is failing and defines a new function or some desired improvement in the code.

2. Second step involves the production of code which can pass the test.

3. Third and the final step involves the re-factoring of the new code in order to meet the prescribed standards.

This development strategy or process was introduced in the year of 2003 by Kent beck. The first programming concepts of the extreme programming or XP are considered to be related to the concepts of the test driven development to some extent.

But, nowadays the test driven development has been observed to be an individual development methodology with its own rules and independent procedures. The test driven development process has proved to be successful in improving and debugging legacy code that has been developed using the older development techniques. 

We all know that every development process has its own requirements so here in this the requirements are the automated unit tests that provide a definition of the code requirements and create the associated code themselves. 

Test Driven Development Cycle

Now let us describe the test driven development cycle in detail and sequence:

1. Adding of a test: 

- In test driven development, for every feature to be added, first a test is written that is inevitably expected to fail since it is written before the actual implementation of the features. 

- If the test does not fail, then there are two probabilities: the test is either wrongly formulated or the feature for which the test has been created already exists. 

- The test should be written with utmost understanding of the specifications and requirements which can be achieved from the use cases and user stories. 

- An already existing test can also be modified.

- Writing unit tests before the implementation of the feature helps the software developer or program focus up on the requirements before the actual code is written. 

- This feature of the test driven development differentiates it from the others and leaves a subtle and important effect.

2. Execution of all the tests and check if they fail: 

- This step involves the validation of the test harnesses for their proper working.

- This is done to ensure that no test passes mistakenly without requirement of new code. 

- The test itself is also tested but in the negative so that all the possibilities of passing of the new test are ruled out making it worthless.

3. Production of code: 

- This step involves the production of code by virtue of which the test will pass.

- The code even if its no perfect is accepted since later it can be improved.

4. Execution of the automated tests: 

After all the tests have passed, the developer can be confident that the code is perfect.

5. Refactorization of the code: 

This involves clean up drive of the code and the tests can be re- executed in order to ensure that the existing code is not being damaged.

6. Repetition: 

This involves repetitions of the whole development cycle in order to improve functionality.