Getting Started¶

Installation¶

Some is published as three artifacts. Pick one base artifact for your platform. Add some-kotest only if you use Kotest property testing.

Upgrading from an older version?

If you are migrating from 0.2.1, see the 0.2.1 to 0.2.2 migration guide.

dependencies {
    // Kotlin/JVM or Java tests
    testImplementation("dev.appoutlet:some-core:{version}")

    // Android tests, including Android framework and Compose UI types.
    // Includes the shared Some API, so do not also add some-core.
    testImplementation("dev.appoutlet:some-android:{version}")

    // Optional: Kotest property testing integration.
    // Add this alongside either some-core or some-android.
    testImplementation("dev.appoutlet:some-kotest:{version}")
}

Do not add both some-core and some-android. Android projects should use some-android only.

Usage¶

The simplest way to use Some is with the top-level some<T>() function:

import dev.appoutlet.some.some

data class User(val name: String, val age: Int)

val user = some<User>()
// User(name=xvqkpmnz, age=42)

It works with nested data classes, collections, and sealed classes — everything is resolved automatically without configuration:

data class Address(val street: String, val city: String)
data class Person(val name: String, val address: Address)

val person: Person = some<Person>()
val users: List<User> = some<List<User>>()

sealed class PaymentMethod {
    data class Card(val last4: String) : PaymentMethod()
    data class BankTransfer(val iban: String) : PaymentMethod()
    object Cash : PaymentMethod()
}

val payment: PaymentMethod = some<PaymentMethod>()

Using it in a test¶

Here's how Some fits into a typical JUnit 5 test. Instead of hand-crafting test data, you generate a realistic fixture with some<T>() and pass it to the code under test:

class WelcomeEmail {
    fun render(user: User) = "Hi ${user.name}, welcome! Verify your email at ${user.email}."
}

class WelcomeEmailTest {
    private val email = WelcomeEmail()

    @Test
    fun `render includes user name and email in the message`() {
        // Create the object that will be used
        val user = some<User>()

        // Pass the generated object on the function you want to test
        val message = email.render(user)

        // Do the assertions you would normally do, using your favourite assertion library
        assertTrue(user.name in message)
        assertTrue(user.email in message)
    }
}

Basic configuration¶

When you need control over the generated data, pass a config lambda to some. The seed guarantees reproducibility, StringStrategy.Readable makes failures easier to debug, and CollectionStrategy(2..4) limits list sizes to a known range:

val user = some<User> {
    strategy(StringStrategy.Readable)
}
// User(name=string-1234, age=17)

val users = some<List<User>> {
    strategy(CollectionStrategy(2..4))
}
// [User(name=string-1234, age=17), User(name=string-5678, age=23)]

For more configuration use cases and details, see the Configuration overview, Strategies, and Supported Types.

Requirements¶

Kotlin 2.3.0+ — required for typeOf<T>() and other type introspection APIs
JVM 17+ — some-core targets JVM 17+
Android minSdk 26 — use some-android for Android projects