Decompose Detekt Rules

Decompose is a Kotlin Multiplatform library for breaking down your code into tree-structured lifecycle-aware business logic components (aka BLoC), with routing functionality and pluggable UI. The Decompose Detekt Rules are a set of custom detekt rules that help you avoid critical mistakes when working with Decompose.

Quick start

Specify the dependency on this set of rules using detektPlugins:

detektPlugins("io.github.ajiekcx.detekt:decompose-detekt-rules:0.2.0")

Rules

DecomposeComponentContextRule

A common mistake is to create a Decompose ComponentContext inside a Composable function scope. For example:

class MainActivity: ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        setContent {
            // DON'T DO THIS
            val context = defaultComponentContext()
        }
    }
}

If recomposition occurs without Activity recreation, you will get the following exception:

java.lang.IllegalArgumentException: SavedStateProvider with the given key is already registered

Avoid using the defaultComponentContext function inside Composable functions.

SerializableDiscriminatorRule

Decompose uses the kotlinx.serialization library to serialize component configurations. A common mistake is naming a property the same as the class discriminator (default: "type"). For example:

import kotlinx.serialization.Serializable

@Serializable
sealed class ScreenConfig {
    @Serializable
    data object Input : ScreenConfig()

    @Serializable
    data class Details(
        val message: String,
        val type: String // DON'T DO THIS
    ) : ScreenConfig()
}

If Decompose attempts to serialize this component configuration, you will encounter the following exception:

java.lang.IllegalStateException: Sealed class 'ScreenConfig.Details' cannot be serialized as base class 'ScreenConfig' because it has property name that conflicts with JSON class discriminator 'type'.

Do not name properties in polymorphic serializable classes as a class discriminator.

Enabling rules

By default, all rules are enabled, but you can configure them in your detekt.yml configuration file:

DecomposeRuleSet:
  DecomposeComponentContextRule:
    active: true
  SerializableDiscriminatorRule:
    active: true
    classDiscriminator: 'type' # optional