Introduction to unit testing and its importance

While testing is absolute necessary in application development, many novice developers get away with a few basic questions regarding testing. They are:

• What is unit testing? and why is it a developer's job?
• Why is unit testing so important?
• And, do we need to write unit tests for each section of our programs?

We will start this chapter by answering these basic questions. If you would like to rather start with testing using RxKotlin directly, you can skip the first few sections in this chapter and start from Testing tools in RxKotlin. Though I would encourage you to read the chapter throughout, even if you have previous experience in testing with Kotlin.

Let's start by defining unit testing. Unit testing is a level of software testing where  the individual smallest testable components of a software (aka application), called units are tested. The purpose is to validate that each unit of the software performs as it was supposed to.

Unit tests can be...