Support modifying 'setting.gradle.kts' as well.

Test dsl will update 'settings.gradle.kts' with required plugin
management block.

^KT-45745 In Progress

Author: Tapchicoma

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/testbase/projectSetupDefaults.kt

@@ -14,11 +14,79 @@ internal val DEFAULT_GROOVY_SETTINGS_FILE =
         repositories {
             mavenLocal()
             mavenCentral()
+            google()
+            gradlePluginPortal()
         }
 
         plugins {
             id "org.jetbrains.kotlin.jvm" version "${'$'}kotlin_version"
             id "org.jetbrains.kotlin.kapt" version "${'$'}kotlin_version"
+            id "org.jetbrains.kotlin.android" version "${'$'}kotlin_version"
+            id "org.jetbrains.kotlin.js" version "${'$'}kotlin_version"
+            id "org.jetbrains.kotlin.multiplatform" version "${'$'}kotlin_version"
+            id "org.jetbrains.kotlin.test.fixes.android" version "${'$'}kotlin_version"
+        }
+        
+        resolutionStrategy {
+            eachPlugin {
+                switch (requested.id.id) {
+                    case "com.android.application":
+                    case "com.android.library":
+                    case "com.android.test":
+                    case "com.android.dynamic-feature":
+                    case "com.android.asset-pack":
+                    case "com.android.asset-pack-bundle":
+                    case "com.android.lint":
+                    case "com.android.instantapp":
+                    case "com.android.feature":
+                        useModule("com.android.tools.build:gradle:${'$'}android_tools_version")
+                        break
+                    case "kotlin-dce-js":
+                        useModule("org.jetbrains.kotlin:kotlin-gradle-plugin:${'$'}kotlin_version")        
+                        break
+                }
+            }
+        }
+    }
+    """.trimIndent()
+
+@Language("kts")
+internal val DEFAULT_KOTLIN_SETTINGS_FILE =
+    """
+    pluginManagement {
+        repositories {
+            mavenLocal()
+            mavenCentral()
+            google()
+            gradlePluginPortal()
+        }
+
+        val kotlin_version: String by settings
+        val android_tools_version: String by settings
+        plugins {
+            id("org.jetbrains.kotlin.jvm") version kotlin_version
+            id("org.jetbrains.kotlin.kapt") version kotlin_version
+            id("org.jetbrains.kotlin.android") version kotlin_version
+            id("org.jetbrains.kotlin.js") version kotlin_version
+            id("org.jetbrains.kotlin.multiplatform") version kotlin_version
+            id("org.jetbrains.kotlin.test.fixes.android") version kotlin_version
+        }
+        
+        resolutionStrategy {
+            eachPlugin {
+                when (requested.id.id) {
+                    "com.android.application",
+                    "com.android.library",
+                    "com.android.test",
+                    "com.android.dynamic-feature",
+                    "com.android.asset-pack",
+                    "com.android.asset-pack-bundle",
+                    "com.android.lint",
+                    "com.android.instantapp",
+                    "com.android.feature" -> useModule("com.android.tools.build:gradle:${'$'}android_tools_version")
+                    "kotlin-dce-js" -> useModule("org.jetbrains.kotlin:kotlin-gradle-plugin:${'$'}kotlin_version")        
+                }
+            }
         }
     }
     """.trimIndent()

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/testbase/testDsl.kt

@@ -231,26 +231,41 @@ private fun setupProjectFromTestResources(
 }
 
 private fun Path.addDefaultBuildFiles() {
-    if (Files.exists(resolve("build.gradle"))) {
-        val settingsFile = resolve("settings.gradle")
-        if (!Files.exists(settingsFile)) {
-            settingsFile.toFile().writeText(DEFAULT_GROOVY_SETTINGS_FILE)
-        } else {
-            val settingsContent = settingsFile.toFile().readText()
-            if (!settingsContent
-                    .lines()
-                    .first { !it.startsWith("//") }
-                    .startsWith("pluginManagement {")
-            ) {
-                settingsFile.toFile().writeText(
-                    """
-                    $DEFAULT_GROOVY_SETTINGS_FILE
-                    
-                    $settingsContent
-                    """.trimIndent()
-                )
+    addPluginManagementToSettings()
+
+    val buildSrc = resolve("buildSrc")
+    if (Files.exists(buildSrc)) {
+        buildSrc.addPluginManagementToSettings()
+    }
+}
+
+internal fun Path.addPluginManagementToSettings() {
+    val settingsGradle = resolve("settings.gradle")
+    val settingsGradleKts = resolve("settings.gradle.kts")
+    when {
+        Files.exists(settingsGradle) -> settingsGradle.modify {
+            if (!it.contains("pluginManagement {")) {
+                """
+                |$DEFAULT_GROOVY_SETTINGS_FILE
+                |                    
+                |$it
+                |""".trimMargin()
+            } else {
+                it
+            }
+        }
+        Files.exists(settingsGradleKts) -> settingsGradleKts.modify {
+            if (!it.contains("pluginManagement {")) {
+                """
+                |$DEFAULT_KOTLIN_SETTINGS_FILE
+                |
+                |$it
+                """.trimMargin()
+            } else {
+                it
             }
         }
+        else -> settingsGradle.toFile().writeText(DEFAULT_GROOVY_SETTINGS_FILE)
     }
 }