My notes on Kotlin and libraries associated with Kotlin. Notes in the public.

Concepts

TBD

New Function Types

• Extension functions
• Scoped functions

Inline value class

Zero cost value objects

• http://kotlinlang.org/docs/inline-classes.html

// For JVM backends
@JvmInline
value class Password(private val s: String)

Trailing lambda function

• https://kotlinlang.org/docs/lambdas.html#passing-trailing-lambdas

val product = items.fold(1) { acc, e -> acc * e }

Libraries

mockk

https://mockk.io/

kotest

https://kotest.io/

Kotlin testing library alternative to JUnit. Testing Framework, Assertion Library and Property Testing.

Notes:

• Unlike JUnit, by default when tests are run, each class is instantiated and each test is run. This means, for example, mockk instances aren’t reset between tests.
• Different testing styles

// Annotation Spec (similar to JUnit)

class AnnotationSpecExample : AnnotationSpec() {

    @BeforeEach
    fun beforeTest() {
        println("Before each test")
    }

    @Test
    fun test1() {
        1 shouldBe 1
    }

    @Test
    fun test2() {
        3 shouldBe 3
    }
}