Quick Guide to Using Unit Tests

by Owais Mushtaq

A unit is the smallest possible testable piece of an application like functions, classes, procedures, interfaces. Unit testing is a system by which singular units of source code are tested to determine and independently scrutinized for proper operation.

When a set/group of input area is given to the unit then it ought to come back with correct values. It ought to handle failures graciously throughout the course of execution once any invalid input is given. A unit takes a look and provides a written contract that the piece of code should assure. White Box Testing technique is employed for executing the unit test.

Unit test has to be written before we start writing the code. It has to be performed after every fix, writing new lines of code or functionality, before integration, and has to be exclusively done by the developers.

Why Unit Tests

The percentage of problems are higher at early stage of development. Since, unit testing is performed by developers were they test their individual code before integration is really performed, the problem is found/captured early and is resolved at that stage of development and hence does not impact other functionalities. This permits developers to create new modules of product in consideration with impact on alternative modules at early stage of development and also helps them in future for implementing new functionalities. Thus, making development method faster and safer, in addition to maintaining an ever-changing code. Since the bugs area unit are found early in unit testing it conjointly helps in reducing price of bug fixes. Tests provide a security cover, permitting refactor at any time without worrying of breaking existing code, thus we will perpetually improve the look of the program.

Reasons To Start Unit Tests

Cost Penalty

Most software nowadays is coded, tested in an adhoc fashion, then handed  off to the QA team, that finds bugs and reports them to developers. But, this method wastes time and cash. Industry analysis show that the value to repair a defect jumps by an order of magnitude at every phase of the SDLC. This implies fixing a bug in QA will price one hundred times more than fixing it in development.


Source: Applied Software Measurement, Capers Jones, 1996

More Hacks, Less Flexibility

Developers grasp from experience the code in legacy apps is fragile and is at risk of bugs, however they lack the tools to efficiently handle and catch these regressions.

Naturally, rather than redesigning or refactoring a legacy app, a developer instead resorts to “localized fixes” (also known as hacks, kludges, and band-aids) in an endeavor to cause as very little injury as possible. Even if a developer is extremely careful, regressions usually penetrate, several of them not noticed till a client reports a problem. Over time, the buildup of these native fixes makes code even more harder to reinforce.

Unit Testing is the Solution

Unit testing is a straightforward and effective concept that improves time-to-market, quality, adaptability and flexibility. The key plan is that every piece of code needs its own tests and also the test should be written by the developer performing it. Enabling developers to check their code as they write it ensures that quality is made in from the beginning of project. Having unit tests makes it easier and safer to change the code as a result of the tests document results, protect the intended behavior and can instantly catch any regressions.

Automation Helps get it Done

Unit testing is the right technique, however it isn’t easy to pin point the areas that have risk of failures. Ideally, every developer ought to  write tests to validate every individual method, functionality or class, as they’re being written. It takes time to spot the risky areas, write tests, run tests, monitor the results, and pinpoint more areas for testing. And it’s robust for any individual to imagine the unexpected, items they never counted on happening. Automation will facilitate to an extent.

Testing Forces you to Slow Down and Think

When adding a brand new feature or refactoring an existing solution, testing forces you to rely on what the code is meant to accomplish. By writing tests 1st, you’re thinking of a way to use the public API and what the ultimate outcome ought to be. So you finish up with a clean and straightforward design that does specifically what you expect it first.

Testing Makes Development Faster

First of all it takes time to think about the functionalities and  writing smart tests for incorporating them. However as time goes on, your overall rate will increase as a result of your not perpetually worrying about breaking existing code as you add new features.

We have additionally found that with smart tests, we will ignore internal implementation details throughout the primary iteration. As long as we tend to get the public API right, we will improve internal design and algorithms later, once more without concern of breaking a single thing. We’ve got used to this specifically for things like sorting algorithms. Within the 1st iteration, we tend to do one thing fast and dirty, like a bubble sort. We will continuously come later and replace it with a far better algorithmic rule, if necessary.

Tests Reduce Fear

One of the biggest fears that programmers encounter is creating an amendment to a bit of code and not knowing what’s attending to break. Having an entire test suite permits programmers to get rid of the worry of creating changes or adding new features. We’ve found that we tend not to hesitate to change and improve well-tested code, whereas we fear changing untested code.

If you would like to scale back price, fear, and build quicker development to deliver the most effective product you ought to begin writing Unit tests.

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