What Developers Should Know About Testing


Learn about using testing in software development along with some basic principles of unit testing.

What Is Testing?

What Is a Unit Test?

How Do I Start Writing Tests?

What Are the Benefits of Unit Tests?

Developers should know about testing, Unit testing is a method of software testing where individual units/ components of a software are tested to verify that each unit works as expected. A unit is the smallest testable part of any software. It usually has one or a few inputs and usually a single output.

In procedural programming, a unit could be an entire module, but it is more commonly an individual function or procedure. In object-oriented programming, a unit is often an entire interface, such as a class, but could be an individual method. Unit tests are created by programmers or occasionally by white box testers during the development process.

One of the keys to good unit testing is that each test case is independent from the others; isolation from change (which we’ll get to later) is important. This allows sectioning the code into units which can be tested in isolation from the remainder of the code, and then composing the code into integrated applications which have been shown to work.

A unit test provides a strict, written contract that the piece of code must satisfy. As a result, it affords several benefits.

– The developer gains confidence that his/her code works as expected and meets requirements defined in the specification (documentation).

– If future changes to

Real software engineers can write Fortran in any language.

– Larry Wall

Those who can’t do, teach.

– Bertrand Russell

In a previous article I wrote about some of the characteristics of software developers who write code that is easy to test. In this article, I’ll discuss testing itself. We will begin with the basics of unit testing and then look at some best practices for writing test cases. Along the way we will see that while unit testing is simple in concept, it can be difficult in practice. But it doesn’t have to be so hard.

The Road to Unit Testing

Unit testing can help reduce the amount of time you spend debugging and refactoring code. If you have a bug in your code, it is much easier to track down and fix if you have unit tests that you can use to verify that the bug has been fixed. In addition, refactoring is much less risky when unit test coverage is good.

Unit testing also helps build confidence in your code. Over time, you will develop a suite of automated tests that run very quickly, and this feedback can help give you confidence in your changes.

When working on a feature or bug fix, it is common practice to write unit tests first—before the code itself—and then implement code to make the tests pass. This process is known as test-driven development (TDD).

Another common approach is behavior-driven development (BDD), which takes an object-oriented approach to creating unit tests for your application by focusing on the expected behavior of an application. BDD gives developers a way to discuss their specifications as well as their functional requirements with clients and other stakeholders.

The benefits of unit testing are not limited to building high-quality software or catching bugs early on in the development process; they also extend beyond coding and into the realm of communication among stakeholders within

Today, testing is well-established and universally accepted as an important part of the software development process. In fact, I would argue that developers who don’t use testing are at a disadvantage, because it is such a powerful tool for improving quality and productivity.

But when I first started to write about software testing in this magazine a couple of years ago, I saw that many developers didn’t pay much attention to it. A few were even hostile. They would say things like “I have never seen any bugs in my code” or “Testing is too much work.”

In response to the first claim, I can only say that if you’ve never seen a bug, you must be writing very simple programs. Sure, if you’re lucky enough to get away with writing small scripts and applications that only last a year or two before being replaced by newer technologies, you may not see many bugs. But if you’re working on large-scale projects that will be maintained for years (and most developers are), they are bound to crop up sooner or later. And if you don’t take the time to test your code thoroughly before releasing it into production, your users will find those bugs.

As for the second objection – that testing takes too much time – I’m going to

1. What Is Unit Testing?

Unit testing is a method of software testing where individual units or components of a software are tested. The purpose is to validate that each unit of the software performs as designed. A unit is the smallest testable part of any software. It usually has one or a few inputs and usually a single output. In procedural programming, a unit could be an entire module, but it is more commonly an individual function or procedure.

The main advantage of unit tests is that they enable you to make changes in your code base without breaking anything. They also make refactoring easier and can improve the design of your code.

There are a number of different types of testing, but one type you’re likely to encounter is unit testing. This article will provide an introduction to unit testing and a few tips on how you can get started writing your own unit tests.

What Is Unit Testing?

Unit testing is a technique in which individual units or components of software are tested to determine if they are fit for use. A unit is the smallest testable part of any software. It usually has one or a few inputs and usually a single output. In procedural programming, a unit could be an entire module, but it is more commonly an individual function or procedure. In object-oriented programming, the smallest unit is a method, which may belong to a base/super class, abstract class or derived/child class.

The purpose of unit testing is to isolate each part of the program and show that the individual parts are correct. A unit test provides a strict, written contract that the piece of code must satisfy. As a result, it affords several benefits:

• The ability to refactor code with confidence

• The ability to run automated regression tests when building your app

• More robust code by finding errors early in the development process

Various tools exist for performing unit tests; some examples include


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