Add applicable .editorconfigs as tasks input

src/main/kotlin/org/jmailen/gradle/kotlinter/tasks/ConfigurableKtLintTask.kt

@@ -1,13 +1,17 @@
 package org.jmailen.gradle.kotlinter.tasks
 
+import org.gradle.api.file.FileCollection
 import org.gradle.api.file.ProjectLayout
 import org.gradle.api.model.ObjectFactory
 import org.gradle.api.provider.ListProperty
 import org.gradle.api.provider.MapProperty
 import org.gradle.api.provider.Property
 import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.InputFiles
 import org.gradle.api.tasks.Internal
 import org.gradle.api.tasks.Optional
+import org.gradle.api.tasks.PathSensitive
+import org.gradle.api.tasks.PathSensitivity
 import org.gradle.api.tasks.SourceTask
 import org.gradle.internal.exceptions.MultiCauseException
 import org.jmailen.gradle.kotlinter.KotlinterExtension.Companion.DEFAULT_DISABLED_RULES
@@ -29,6 +33,12 @@ abstract class ConfigurableKtLintTask(
     @Input
     val disabledRules: ListProperty<String> = objectFactory.listProperty(default = DEFAULT_DISABLED_RULES.toList())
 
+    @get:InputFiles
+    @get:PathSensitive(PathSensitivity.RELATIVE)
+    internal val editorconfigFiles: FileCollection = objectFactory.fileCollection().apply {
+        from(projectLayout.findApplicableEditorConfigFiles().toList())
+    }
+
     @Internal
     protected fun getKtLintParams(): KtLintParams = KtLintParams(
         indentSize = indentSize.orNull,

src/main/kotlin/org/jmailen/gradle/kotlinter/tasks/EditorConfigUtils.kt

@@ -0,0 +1,30 @@
+package org.jmailen.gradle.kotlinter.tasks
+
+import org.gradle.api.file.ProjectLayout
+import java.io.File
+
+internal fun ProjectLayout.findApplicableEditorConfigFiles(): Sequence<File> {
+    val projectEditorConfig = projectDirectory.file(".editorconfig").asFile
+
+    return generateSequence(seed = projectEditorConfig) { editorconfig ->
+        if (editorconfig.isRootEditorConfig) {
+            null
+        } else {
+            editorconfig.parentFile?.parentFile?.resolve(".editorconfig")
+        }
+    }
+}
+
+private val File.isRootEditorConfig: Boolean
+    get() {
+        if (!isFile || !canRead()) return false
+
+        return useLines { lines ->
+            lines.any { line -> line.matches(editorConfigRootRegex) }
+        }
+    }
+
+/**
+ * According to https://editorconfig.org/ root-most EditorConfig file contains line with `root=true`
+ */
+private val editorConfigRootRegex = "^root\\s?=\\s?true".toRegex()

src/test/kotlin/org/jmailen/gradle/kotlinter/functional/KotlinProjectTest.kt

@@ -3,6 +3,7 @@ package org.jmailen.gradle.kotlinter.functional
 import org.gradle.testkit.runner.TaskOutcome.FAILED
 import org.gradle.testkit.runner.TaskOutcome.SUCCESS
 import org.gradle.testkit.runner.TaskOutcome.UP_TO_DATE
+import org.jmailen.gradle.kotlinter.functional.utils.editorConfig
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertTrue
 import org.junit.Before
@@ -14,13 +15,15 @@ internal class KotlinProjectTest : WithGradleTest.Kotlin() {
     private lateinit var settingsFile: File
     private lateinit var buildFile: File
     private lateinit var sourceDir: File
+    private lateinit var editorconfigFile: File
     private val pathPattern = "(.*\\.kt):\\d+:\\d+".toRegex()
 
     @Before
     fun setup() {
         settingsFile = testProjectDir.newFile("settings.gradle")
         buildFile = testProjectDir.newFile("build.gradle")
         sourceDir = testProjectDir.newFolder("src", "main", "kotlin")
+        editorconfigFile = testProjectDir.newFile(".editorconfig")
     }
 
     @Test
@@ -120,6 +123,7 @@ internal class KotlinProjectTest : WithGradleTest.Kotlin() {
     fun `tasks up-to-date checks`() {
         settingsFile()
         buildFile()
+        editorConfig()
         kotlinSourceFile(
             "CustomObject.kt",
             """
@@ -141,6 +145,14 @@ internal class KotlinProjectTest : WithGradleTest.Kotlin() {
         build("formatKotlin").apply {
             assertEquals(SUCCESS, task(":formatKotlin")?.outcome)
         }
+
+        editorconfigFile.appendText("content=updated")
+        build("lintKotlin").apply {
+            assertEquals(SUCCESS, task(":lintKotlin")?.outcome)
+        }
+        build("lintKotlin").apply {
+            assertEquals(UP_TO_DATE, task(":lintKotlin")?.outcome)
+        }
     }
 
     @Test
@@ -178,6 +190,10 @@ internal class KotlinProjectTest : WithGradleTest.Kotlin() {
         writeText("rootProject.name = 'kotlinter'")
     }
 
+    private fun editorConfig() = editorconfigFile.apply {
+        writeText(editorConfig)
+    }
+
     private fun buildFile() = buildFile.apply {
         // language=groovy
         val buildscript =