konsist-architecture-tests

Konsist architecture tests

Overview

Enforce module-boundary invariants as plain JVM unit tests with Konsist, which parses Kotlin source straight from disk. Each violation turns the suite red the moment a forbidding import is written — before review, before the dependency graph is even wired. The check is on imports (source-level), the right altitude: a stray dependencies {} edge can sit unnoticed, but the first illegal import that relies on it fails.

Why Konsist — not ArchUnit or Detekt

This is the non-obvious decision; get it right first.

• ArchUnit reads compiled bytecode off a classpath. A pure commonMain / iosMain KMP module never hands a JVM test task its bytecode, so ArchUnit can't see that code at all. Konsist reads source, so it sees every source set.
• Detekt wants a Gradle plugin per module; on com.android.kotlin.multiplatform.library (AGP 9) plugin-compat lags and KMP source-set wiring is awkward.
• Konsist needs no plugin and no classpath: Konsist.scopeFromProject() walks the whole repo from a single host test — the same "rule as a host test" shape as other structural checks. One prevention mechanism, not two.

Where it lives + wiring

Put it in one JVM test source set that runs testDebugUnitTest — conventionally the app module (it already depends on everything, but Konsist scans the whole project from disk regardless of which module hosts the test):

app/src/test/kotlin/<base.package>/architecture/ArchitectureTest.kt

Add the dependency to that module: testImplementation(libs.konsist) (catalog: konsist = { module = "com.lemonappdev:konsist", version.ref = "konsist" }). Run just these rules:

./gradlew :app:testDebugUnitTest --tests "<base.package>.architecture.ArchitectureTest"

Survey the graph, then write one rule per edge

Read settings.gradle(.kts) and the module folders. For each intended dependency direction (core ← feature, api is a seam over impl, domain ↛ data, …), write one @Test. Don't invent rules the project doesn't hold.