Kwik

Property-based testing library for Kotlin.

Main features:

• Test-engine agnostic
• Multiplatform
• No reflection
• Configurable built-in generators
• Easy way to create and combine generators
• Seeded generation for reproducible results

Planned features:

• Shrinking

Find more information on https://kwik.readthedocs.io

Status

The project is incubating and its API is subject to changes.

Please give it a try and write a feedback in the issues or discuss on gitter.

For mode details about the future of kwik, here's a roadmap.

How it looks like

class PlusOperatorTest {

    @Test
    fun isCommutative() = forAll { x: Int, y: Int ->
        x + y == y + x
    }

    @Test
    fun isAssociative() = forAll(iterations = 1000) { x: Int, y: Int, z: Int ->
        (x + y) + z == x + (y + z)
    }

    @Test
    fun zeroIsNeutral() = forAll(seed = -4567) { x: Int ->
        x + 0 == x
    }
}

For more information read the usage and look at the available generators

Motivation

Property based testing is great and very powerful. But despite the fact that many good libraries already exist, none of them fully fit my needs.

The known alternatives either:

• Are bound to a specific test-engine
• Can only be used when compiling kotlin to Java (and cannot be used in multi-platform projects)
• Relies on reflection, making the tests slower and make some errors detectable only at runtime
• Do not allow enough freedom and safety to customize existing generators
• Force the user to add unwanted dependencies in the classpath

Requirements

• Kotlin version: 1.4.0 or newer
• JDK version: 8, 11 or 15

Setup

Example of setup using gradle.

repositories {
    jcenter()
}

dependencies {
    testCompile("com.github.jcornaz.kwik:kwik-core-jvm:$kwikVersion")
}

Find more detailed information in the setup instructions.

Contribute

See how to contribute