Fixture for Kotlin

Write maintainable unit tests, faster.

Fixture makes it easier to create non-relevant data for test fixtures, allowing the developer to focus on the essentials of each test case.

Credits: Fixture is inspired by AutoFixture and QuickCheck.

This project is currently experimental and the API subject to breaking changes without notice.

Getting Started

Step 1. Add it in your root build.gradle at the end of repositories:

allprojects {
	repositories {
		maven { url "https://jitpack.io" }
	}
}

Step 2. Add the dependency

dependencies {
	testImplementation 'com.github.marcellogalhardo:kotlin-fixture:{Tag}'
	androidTestImplementation 'com.github.marcellogalhardo:kotlin-fixture:{Tag}'
}

(Please replace {Tag} with the latest version numbers: )

Basic Usage

Fixture is designed to make Test-Driven Development more productive and unit tests more refactoring-safe. It does so by removing the need for hand-coding anonymous variables as part of a test's Fixture Setup phase.

When writing unit tests, you typically need to create some objects that represent the initial state of the test. Often, an API will force you to specify much more data than you really care about, so you frequently end up creating objects that have no influence on the test, simply to make the code compile.

Fixture can help by creating such Anonymous Variables for you. Here's a simple example:

@Test
fun testExample() {
    // Arrange
    val expectedName = Fixture.string(prefix = "name") // name-6223529b-3497-45c8-a864-8a969cd798e4
    val sut = SystemUnderTest()

    // Act
    val result = sut.echo(expectedName)

    // Assert
    assertTrue(result == expectedName)
}

This example illustrates the basic principle of Fixture.

Warning: This library does work outside tests but it was not designed for it. Use it at your own risk.

Disclaimer: This library will be migrated to Maven Central as soon as it moves out of experimental status.

Usage

All examples assume that a Fixture instance has previously been created like this:

val fixture = Fixture()

Basic Types

Type	Sample	Result
Boolean	fixture.boolean()	Boolean: false
Char	fixture.char()	Char: A
Double	fixture.double()	Double: 400
Float	fixture.float()	Float: 40.5
Int	fixture.int()	Int: 27
Long	fixture.long()	Long: 5
String	fixture.string()	String: "f5cdf6b1-a473-410f-95f3-f427f7abb0c7"

Generate Complex Type

val generated = Fixture.generate {
    ComplexParent(
        name = string(prefix = "parent"),
        number = int(),
        child = ComplexChild(name = string(prefix = "child"))
    )
}

Generators for Reusability

val complexChildGenerator = Fixture.generator {
    ComplexChild(name = string(prefix = "child") /* other properties */)
}
val complexParentGenerator = Fixture.generator {
    ComplexParent(
        name = string(prefix = "parent"),
        number = int(),
        child = complexChildGenerator.generate()
    )
}
val complexParent = complexParentGenerator.generate()

Generate Lists

val stringList = Fixture.list(until = 10) { index -> string(prefix = index.toString()) }

• Sample result:
  • List<String>
    • String: "0-ecc1cc75-cd7a-417f-b477-2913802440b4"
    • String: "1-fce70a7b-fae5-474f-8055-415ca46eac20"
    • String: "2-79b45532-d66f-4abc-9311-77ba68dc9e3c"

Generate Maps

val intToStringMap = Fixture.map(until = 10) { index -> index to string() }

• Sample result:
  • Map<Int, String>
    • Pair<Int, String>: 0 to "ecc1cc75-cd7a-417f-b477-2913802440b4"
    • Pair<Int, String>: 1 to "fce70a7b-fae5-474f-8055-415ca46eac20"
    • Pair<Int, String>: 2 to "79b45532-d66f-4abc-9311-77ba68dc9e3c"