Kotlin convention

Basically, all rules are based on the following.

• https://developer.android.com/kotlin/style-guide
• https://kotlinlang.org/docs/reference/coding-conventions.html

For applying those rules programatically, I used ktlint.

Customed rules are below and I attached a link relate to the section.

Class layout

Common rule for everywhere

• Need a new line between all elements
• Put related stuff together by visibility
• Declaration order is public > internal > protected > private in all area
• For readability set API method for public and implement it with the protected or private keyword

Structure

Property

• val
• val by lazy
• var
• lateinit var

Initializer block

Secondary constructor

• Prefer to use primary constructor first with arguments
• private fun

Method declarations

• fun
• override fun
• private fun

Interface declarations

Nested class

companion object

Naming rule

• Don't use an Uppercase letter more than 2 for class and method like not OEBPS but Oepbs.
• Don't use the abbreviation for the name of class and method if possible.
• The common term first then the concrete term.

About android

• The key name follows snake_case
• Convert snake_case resource id to camelCase variable through data binding.
• The extra key has to start with the package name and be named snake_case if it's access public.

About test

Naming rules

• Method name has to be started with given_when_then.
• Use the abbreviation for the name of the variable if possible.

AAA

• Distinct Arrange-Action-Assertion area clearly in method.
  • Define input in Arrange
  • Define actual and expect in Action
  • Define assertion with actual and expect

Use BeforeAll/AfterAll

• All test method has to be an independent task.

In Project

• xxxPath() method has to return with postfix of /.