[Gradle][KT-53342] Implement KotlinAndroidSourceSetLayoutExtensionTest

libraries/tools/kotlin-gradle-plugin/src/functionalTest/kotlin/org/jetbrains/kotlin/gradle/sources/android/KotlinAndroidSourceSetLayoutExtensionTest.kt

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2010-2022 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+@file:Suppress("FunctionName")
+
+package org.jetbrains.kotlin.gradle.sources.android
+
+import org.gradle.testfixtures.ProjectBuilder
+import org.jetbrains.kotlin.gradle.mpp.buildProjectWithMPP
+import org.jetbrains.kotlin.gradle.plugin.KotlinAndroidPluginWrapper
+import org.jetbrains.kotlin.gradle.plugin.sources.android.kotlinAndroidSourceSetLayout
+import org.jetbrains.kotlin.gradle.plugin.sources.android.multiplatformAndroidSourceSetLayoutV1
+import org.jetbrains.kotlin.gradle.plugin.sources.android.multiplatformAndroidSourceSetLayoutV2
+import org.jetbrains.kotlin.gradle.plugin.sources.android.singleTargetAndroidSourceSetLayout
+import org.jetbrains.kotlin.gradle.setAndroidMultiplatformSourceSetLayoutVersion
+import org.junit.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertFailsWith
+
+class KotlinAndroidSourceSetLayoutExtensionTest {
+
+    @Test
+    fun `single platform plugin`() {
+        val project = ProjectBuilder.builder().build()
+        project.plugins.apply(KotlinAndroidPluginWrapper::class.java)
+        assertEquals(singleTargetAndroidSourceSetLayout, project.kotlinAndroidSourceSetLayout)
+
+        project.setAndroidMultiplatformSourceSetLayoutVersion(1)
+        assertEquals(singleTargetAndroidSourceSetLayout, project.kotlinAndroidSourceSetLayout)
+
+        project.setAndroidMultiplatformSourceSetLayoutVersion(2)
+        assertEquals(singleTargetAndroidSourceSetLayout, project.kotlinAndroidSourceSetLayout)
+    }
+
+    @Test
+    fun `test multiplatform plugin`() {
+        val project = buildProjectWithMPP { }
+
+        assertEquals(
+            multiplatformAndroidSourceSetLayoutV1, project.kotlinAndroidSourceSetLayout,
+            "Expected v1 being set as default"
+        )
+
+        project.setAndroidMultiplatformSourceSetLayoutVersion(2)
+        assertEquals(multiplatformAndroidSourceSetLayoutV2, project.kotlinAndroidSourceSetLayout)
+
+        project.setAndroidMultiplatformSourceSetLayoutVersion(1)
+        assertEquals(multiplatformAndroidSourceSetLayoutV1, project.kotlinAndroidSourceSetLayout)
+
+        /* Test unhappy path: Layout version 0 is unknown/unsupported */
+        project.setAndroidMultiplatformSourceSetLayoutVersion(0)
+        assertFailsWith<IllegalArgumentException> {
+            project.kotlinAndroidSourceSetLayout
+        }
+    }
+}