[Gradle][MPP] Add test cases for KotlinTargetHierarchy*

^KT-53570 Verification Pending

libraries/tools/kotlin-gradle-plugin/src/functionalTest/kotlin/org/jetbrains/kotlin/gradle/KotlinTargetHierarchyDescriptorTest.kt

@@ -189,6 +189,54 @@ class KotlinTargetHierarchyDescriptorTest {
             cycleStack
         )
     }
+
+    @Test
+    fun `test - filterCompilations`() {
+        val descriptor = KotlinTargetHierarchyDescriptor {
+            filterCompilations { it.name in setOf("a", "b") }
+            common {
+                group("x") {
+                    includeCompilationIf { true }
+                }
+            }
+        }
+
+        assertEquals(
+            hierarchy {
+                group("common") {
+                    group("x")
+                }
+            },
+            descriptor.buildKotlinTargetHierarchy(kotlin.linuxX64().compilations.maybeCreate("a"))
+        )
+
+        assertEquals(
+            descriptor.buildKotlinTargetHierarchy(kotlin.linuxX64().compilations.maybeCreate("a")),
+            descriptor.buildKotlinTargetHierarchy(kotlin.linuxX64().compilations.maybeCreate("b"))
+        )
+
+        assertNull(
+            descriptor.buildKotlinTargetHierarchy(kotlin.linuxX64().compilations.maybeCreate("c"))
+        )
+    }
+
+    @Test
+    fun `test - filterCompilations - include them again`() {
+        val descriptor = KotlinTargetHierarchyDescriptor {
+            includeCompilationIf { true }
+            filterCompilations { it.name == "a" }
+        }
+
+        assertNotNull(descriptor.buildKotlinTargetHierarchy(kotlin.linuxX64().compilations.maybeCreate("a")))
+        assertNull(descriptor.buildKotlinTargetHierarchy(kotlin.linuxX64().compilations.maybeCreate("b")))
+
+        val extended = descriptor.extend {
+            includeCompilationIf { true } // <- adds all compilations back again!
+        }
+
+        assertNull(descriptor.buildKotlinTargetHierarchy(kotlin.linuxX64().compilations.maybeCreate("b")))
+        assertNotNull(extended.buildKotlinTargetHierarchy(kotlin.linuxX64().compilations.maybeCreate("b")))
+    }
 }
 
 private class TestHierarchyBuilder(private val node: Node) {

libraries/tools/kotlin-gradle-plugin/src/functionalTest/kotlin/org/jetbrains/kotlin/gradle/KotlinTargetHierarchyDslTest.kt

@@ -11,8 +11,9 @@ import org.jetbrains.kotlin.gradle.dsl.KotlinMultiplatformExtension
 import org.jetbrains.kotlin.gradle.dsl.multiplatformExtension
 import org.jetbrains.kotlin.gradle.plugin.KotlinSourceSet
 import org.jetbrains.kotlin.gradle.plugin.KotlinTargetHierarchyDescriptor
-import kotlin.test.Test
+import org.jetbrains.kotlin.gradle.plugin.mpp.targetHierarchy.buildKotlinTargetHierarchy
-import kotlin.test.assertEquals
+import org.jetbrains.kotlin.gradle.plugin.mpp.targetHierarchy.naturalKotlinTargetHierarchy
+import kotlin.test.*
 
 class KotlinTargetHierarchyDslTest {
 
@@ -177,6 +178,20 @@ class KotlinTargetHierarchyDslTest {
         )
     }
 
+    @Test
+    fun `test - hierarchy default - is only applied to main and test compilations`() {
+        assertNotNull(naturalKotlinTargetHierarchy.buildKotlinTargetHierarchy(kotlin.linuxX64().compilations.main))
+        assertNotNull(naturalKotlinTargetHierarchy.buildKotlinTargetHierarchy(kotlin.linuxX64().compilations.test))
+        assertNull(naturalKotlinTargetHierarchy.buildKotlinTargetHierarchy(kotlin.linuxX64().compilations.maybeCreate("custom")))
+
+        kotlin.targetHierarchy.default()
+        kotlin.linuxX64().compilations.maybeCreate("custom").defaultSourceSet.let { customSourceSet ->
+            if (customSourceSet.dependsOn.isNotEmpty()) {
+                fail("Expected no dependsOn SourceSets for $customSourceSet (${customSourceSet.dependsOn})")
+            }
+        }
+    }
+
     @Test
     fun `test - hierarchy apply - extend`() {
         val descriptor = KotlinTargetHierarchyDescriptor {