Minor: add test on importing platform of commonMain in single-backend project

idea/idea-gradle/tests/org/jetbrains/kotlin/gradle/HierarchicalMultiplatformProjectImportingTest.kt

@@ -578,6 +578,27 @@ class HierarchicalMultiplatformProjectImportingTest : MultiplePluginVersionGradl
         }
     }
 
+    @Test
+    @PluginTargetVersions(gradleVersionForLatestPlugin = mppImportTestMinVersionForMaster)
+    fun testCommonMainIsSingleBackend() {
+        configureByFiles()
+        importProject()
+
+        val macosX64 = NativePlatforms.nativePlatformBySingleTarget(KonanTarget.MACOS_X64)
+        val linuxX64 = NativePlatforms.nativePlatformBySingleTarget(KonanTarget.LINUX_X64)
+
+        checkProjectStructure(exhaustiveModuleList = false, exhaustiveSourceSourceRootList = false, exhaustiveDependencyList = false) {
+            module("my-app.commonMain") { targetPlatform(macosX64, linuxX64) }
+            module("my-app.commonTest") { targetPlatform(macosX64, linuxX64) }
+
+            module("my-app.linuxX64Main") { targetPlatform(linuxX64) }
+            module("my-app.linuxX64Test") { targetPlatform(linuxX64) }
+
+            module("my-app.macosX64Test") { targetPlatform(macosX64) }
+            module("my-app.macosX64Main") { targetPlatform(macosX64) }
+        }
+    }
+
     private fun checkProjectStructure(
         exhaustiveModuleList: Boolean = true,
         exhaustiveSourceSourceRootList: Boolean = true,

idea/testData/gradle/hierarchicalMultiplatformImport/commonMainIsSingleBackend/build.gradle.kts

@@ -0,0 +1,21 @@
+buildscript {
+    repositories {
+        {{kts_kotlin_plugin_repositories}}
+    }
+}
+
+repositories {
+    {{kts_kotlin_plugin_repositories}}
+}
+
+plugins {
+    kotlin("multiplatform").version("{{kotlin_plugin_version}}")
+}
+
+group = "project"
+version = "1.0"
+
+kotlin {
+    linuxX64()
+    macosX64()
+}

idea/testData/gradle/hierarchicalMultiplatformImport/commonMainIsSingleBackend/gradle.properties

@@ -0,0 +1 @@
+kotlin.mpp.enableGranularSourceSetsMetadata=true

idea/testData/gradle/hierarchicalMultiplatformImport/commonMainIsSingleBackend/settings.gradle.kts

@@ -0,0 +1,9 @@
+pluginManagement {
+    repositories {
+        {{kts_kotlin_plugin_repositories}}
+    }
+}
+
+rootProject.name = "my-app"
+
+enableFeaturePreview("GRADLE_METADATA")