Migrate MocKMP from 2.1 to 3.0

MocKMP 3 changes exactly one thing: the Gradle plugin now targets Android Gradle Plugin 9, and no longer works with AGP 8 or earlier.

Nothing else changed. The runtime, the processor and the test helper are byte-for-byte identical to 2.1: mocking, faking, injection, the mock<T>() / fake<T>() / injectMocks accessors, the TestsWithMocks class and ITestsWithMocks interface, and every annotation all behave exactly as they did.

If your project does not build anything for Android, there is nothing to migrate. Bump the MocKMP version and you are done.

Android projects must move to AGP 9

MocKMP 3.0 cannot be used with AGP 8 or earlier, and MocKMP 2.1 cannot be used with AGP 9. The two versions are the two sides of that boundary — pick the one matching the AGP you are on, and migrate both together.

The reason is not a matter of taste: to compile mocks & fakes for Android, MocKMP has to hand its generated sources to each Android variant. It used to do so through the variant API’s registerJavaGeneratingTask, which AGP 9 removed. MocKMP 3 registers them through androidComponents.onVariants { } instead, which does not exist in AGP 8.

So the migration is an AGP 8 → 9 migration, which MocKMP forces the timing of but does not define. Follow the Android Gradle plugin release notes and upgrade guide as the authority.

What that looked like here

For reference, these are the changes MocKMP’s own Android test projects needed. They are AGP-side changes, not MocKMP ones, but they are the ones you are most likely to meet.

The new DSL is now mandatory, so the opt-out property is gone:

gradle.properties

# android.newDsl=false (1)

1	Remove it; AGP 9 does not accept it.

A plain Android library no longer applies the Kotlin Android plugin separately, and declares its sources on the android extension:

build.gradle.kts

plugins {
    id("com.android.library")
    // id("org.jetbrains.kotlin.android") (1)
    id("com.google.devtools.ksp")
    id("org.kodein.mock.mockmp")
}

// kotlin.sourceSets { (2)
//     main { kotlin.srcDir("...") }
// }
android.sourceSets {
    named("main") {
        kotlin.directories.add("...") (2)
    }
}

1	No longer applied alongside `com.android.library`.
2	Source directories move from `kotlin.sourceSets` / `srcDir` to `android.sourceSets` / `kotlin.directories`.

A Kotlin Multiplatform module targets Android through its own plugin rather than androidTarget():

build.gradle.kts

plugins {
    kotlin("multiplatform")
    id("com.android.kotlin.multiplatform.library") (1)
    id("com.google.devtools.ksp")
    id("org.kodein.mock.mockmp")
}

kotlin {
    // androidTarget() (1)
    android {
        namespace = "com.example.myapplication"
        compileSdk = 36
        minSdk = 24
        withHostTest {} (2)
    }

    sourceSets {
        // androidUnitTest { (3)
        getByName("androidHostTest") { (4)
            dependencies {
                implementation(kotlin("test-junit"))
            }
        }
    }
}

1	`com.android.kotlin.multiplatform.library` plus a `kotlin { android { } }` block replaces `com.android.library` plus `androidTarget()`.
2	Declares the host-side (unit) test compilation, which is not created by default.
3	`androidUnitTest` is the name the old `androidTarget()` plugin used. Left in place it silently belongs to no compilation, and Kotlin reports it as an unused source set.
4	Because the compilation declared above is named `hostTest`, its source set is `androidHostTest`. Kotlin generates no typed accessor for it — the Android target comes from AGP — so name it with `getByName`.

Once the build configures, MocKMP applies exactly as before — the setup documentation is unchanged.