Fixed NPE on StandaloneScriptRootsCache instantiation

Relates to ^EA-218043
#KTIJ-1137 Fixed

Original commit: 1d63a1b48d480b958ff44676c42b698a8ca5f64a

idea/idea-gradle/src/org/jetbrains/kotlin/idea/scripting/gradle/roots/GradleBuildRootIndex.kt

@@ -16,7 +16,9 @@ class GradleBuildRootIndex(private val project: Project) : StandaloneScriptsUpda
         private val standaloneScripts: MutableSet<String>
             get() = StandaloneScriptsStorage.getInstance(project)?.files ?: hashSetOf()
 
-        private val standaloneScriptRoots = mutableMapOf<String, GradleBuildRoot?>().apply {
+        private val standaloneScriptRoots = mutableMapOf<String, GradleBuildRoot?>()
+
+        init {
             standaloneScripts.forEach(::updateRootsCache)
         }
 

idea/idea-gradle/tests/org/jetbrains/kotlin/idea/scripting/gradle/GradleBuildRootIndexTest.kt

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2010-2021 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.
+ */
+
+package org.jetbrains.kotlin.idea.scripting.gradle
+
+import com.intellij.openapi.externalSystem.util.ExternalSystemApiUtil
+import com.intellij.psi.PsiFile
+import org.jetbrains.kotlin.idea.script.AbstractScriptConfigurationLoadingTest
+import org.jetbrains.kotlin.idea.scripting.gradle.roots.GradleBuildRootsManager
+import org.jetbrains.kotlin.idea.scripting.gradle.settings.StandaloneScriptsStorage
+import org.jetbrains.kotlin.psi.KtFile
+import org.jetbrains.plugins.gradle.settings.DistributionType
+import org.jetbrains.plugins.gradle.settings.GradleProjectSettings
+import org.jetbrains.plugins.gradle.util.GradleConstants
+import java.io.File
+
+class GradleBuildRootIndexTest : AbstractScriptConfigurationLoadingTest() {
+    override fun setUpTestProject() {
+        val rootDir = File("idea/testData/script/definition/loading/gradle/")
+
+        val settings: KtFile = copyFromTestdataToProject(File(rootDir, GradleConstants.KOTLIN_DSL_SETTINGS_FILE_NAME).path)
+        val prop: PsiFile = copyFromTestdataToProject(File(rootDir, "gradle.properties").path)
+
+        val gradleCoreJar = createFileInProject("gradle/lib/gradle-core-1.0.0.jar")
+        val gradleWrapperProperties = createFileInProject("gradle/wrapper/gradle-wrapper.properties")
+
+        val buildGradleKts = rootDir.walkTopDown().find { it.name == GradleConstants.KOTLIN_DSL_SCRIPT_NAME }
+            ?: error("Couldn't find main script")
+        configureScriptFile(rootDir.path, buildGradleKts)
+        val build = (myFile as? KtFile) ?: error("")
+
+        val newProjectSettings = GradleProjectSettings()
+        newProjectSettings.gradleHome = gradleCoreJar.parentFile.parent
+        newProjectSettings.distributionType = DistributionType.LOCAL
+        newProjectSettings.externalProjectPath = settings.virtualFile.parent.path
+
+        StandaloneScriptsStorage.getInstance(project)!!.files.add("standalone.kts")
+
+        ExternalSystemApiUtil.getSettings(project, GradleConstants.SYSTEM_ID).linkProject(newProjectSettings)
+    }
+
+    fun `test standalone scripts on start`() {
+        assertNotNull(GradleBuildRootsManager.getInstance(project))
+    }
+}

idea/idea-gradle/tests/org/jetbrains/kotlin/idea/scripting/gradle/GradleScriptListenerTest.kt

@@ -66,18 +66,6 @@ open class GradleScriptListenerTest : AbstractScriptConfigurationLoadingTest() {
         )
     }
 
-    private inline fun <reified T : Any> copyFromTestdataToProject(file: String): T {
-        createFileAndSyncDependencies(File(file))
-        return (myFile as? T) ?: error("Couldn't configure project by $file")
-    }
-
-    private fun createFileInProject(path: String): File {
-        val file = File(project.basePath, path)
-        file.parentFile.mkdirs()
-        file.createNewFile()
-        return file
-    }
-
     fun testSectionChange() {
         assertAndLoadInitialConfiguration(testFiles.buildKts)
 

idea/tests/org/jetbrains/kotlin/idea/script/AbstractScriptConfigurationLoadingTest.kt

@@ -20,6 +20,7 @@ import org.jetbrains.kotlin.idea.core.script.configuration.testingBackgroundExec
 import org.jetbrains.kotlin.idea.core.script.configuration.utils.testScriptConfigurationNotification
 import org.jetbrains.kotlin.idea.util.application.runWriteAction
 import org.jetbrains.kotlin.psi.KtFile
+import java.io.File
 
 abstract class AbstractScriptConfigurationLoadingTest : AbstractScriptConfigurationTest() {
     lateinit var scriptConfigurationManager: CompositeScriptConfigurationManager
@@ -68,6 +69,18 @@ abstract class AbstractScriptConfigurationLoadingTest : AbstractScriptConfigurat
         // do nothings
     }
 
+    protected inline fun <reified T : Any> copyFromTestdataToProject(file: String): T {
+        createFileAndSyncDependencies(File(file))
+        return (myFile as? T) ?: error("Couldn't configure project by $file")
+    }
+
+    protected fun createFileInProject(path: String): File {
+        val file = File(project.basePath, path)
+        file.parentFile.mkdirs()
+        file.createNewFile()
+        return file
+    }
+
     protected fun assertAndDoAllBackgroundTasks() {
         assertDoAllBackgroundTaskAndDoWhileLoading { }
     }