Add baseline support

README.md

@@ -101,14 +101,14 @@ plugins {
 - Incremental build support and fast parallelization with Gradle Worker API
 - Configures from `.editorconfig` when available
 - Configurable reporters
+- Baseline file _(note: you must generate your baseline file with [`ktlint`](https://github.com/pinterest/ktlint))_
 
 ### Tasks
 
 When your project uses one of the supported Kotlin Gradle plugins, Kotlinter adds these tasks:
 
-`formatKotlin`: format Kotlin source code according to `ktlint` rules or warn when auto-format not possible.
-
-`lintKotlin`: report Kotlin lint errors and by default fail the build.
+ - `formatKotlin`: format Kotlin source code according to `ktlint` rules or warn when auto-format not possible.
+ - `lintKotlin`: report Kotlin lint errors and by default fail the build.
 
 Also `check` becomes dependent on `lintKotlin`.
 
@@ -157,6 +157,7 @@ kotlinter {
     reporters = arrayOf("checkstyle", "plain")
     experimentalRules = false
     disabledRules = emptyArray()
+    baseline = File("config/baseline.xml") 
 }
 ```
 
@@ -171,6 +172,7 @@ kotlinter {
     reporters = ['checkstyle', 'plain']
     experimentalRules = false
     disabledRules = []
+    baseline = "config/baseline.xml"
 }
 ```
 
@@ -182,12 +184,14 @@ Reporters behave as described at: https://github.com/pinterest/ktlint
 
 The `experimentalRules` property enables rules which are part of ktlint's experimental rule set.
 
-The `disabledRules` property can includes an array of rule ids you wish to disable. For example to allow wildcard imports:
+The `disabledRules` property can include an array of rule ids you wish to disable. For example to allow wildcard imports:
 ```groovy
 disabledRules = ["no-wildcard-imports"]
 ```
 You must prefix rule ids not part of the standard rule set with `<rule-set-id>:<rule-id>`. For example `experimental:annotation`.
 
+The `baseline` property is a path to a baseline file relative to the module being configured. The baseline file needs to be generated via [`ktlint`](https://github.com/pinterest/ktlint)
+
 ### Editorconfig
 
 Kotlinter will configure itself using an `.editorconfig` file if one is present.

src/main/kotlin/org/jmailen/gradle/kotlinter/KotlinterExtension.kt

@@ -8,6 +8,7 @@ open class KotlinterExtension {
         const val DEFAULT_EXPERIMENTAL_RULES = false
         val DEFAULT_REPORTER = ReporterType.checkstyle.name
         val DEFAULT_DISABLED_RULES = emptyArray<String>()
+        val DEFAULT_BASELINE: String? = null
     }
 
     var ignoreFailures = DEFAULT_IGNORE_FAILURES
@@ -17,4 +18,6 @@ open class KotlinterExtension {
     var experimentalRules = DEFAULT_EXPERIMENTAL_RULES
 
     var disabledRules = DEFAULT_DISABLED_RULES
+
+    var baseline = DEFAULT_BASELINE
 }

src/main/kotlin/org/jmailen/gradle/kotlinter/KotlinterPlugin.kt

@@ -3,6 +3,7 @@ package org.jmailen.gradle.kotlinter
 import org.gradle.api.Plugin
 import org.gradle.api.Project
 import org.gradle.api.Task
+import org.gradle.api.file.RegularFile
 import org.gradle.api.tasks.TaskProvider
 import org.jmailen.gradle.kotlinter.pluginapplier.AndroidSourceSetApplier
 import org.jmailen.gradle.kotlinter.pluginapplier.KotlinSourceSetApplier
@@ -48,6 +49,7 @@ class KotlinterPlugin : Plugin<Project> {
                         )
                         lintTask.experimentalRules.set(provider { kotlinterExtension.experimentalRules })
                         lintTask.disabledRules.set(provider { kotlinterExtension.disabledRules.toList() })
+                        lintTask.baseline = kotlinterExtension.baseline?.let { File(it) }
                     }
                     lintKotlin.configure { lintTask ->
                         lintTask.dependsOn(lintTaskPerSourceSet)

src/main/kotlin/org/jmailen/gradle/kotlinter/support/KtLintParams.kt

@@ -1,8 +1,10 @@
 package org.jmailen.gradle.kotlinter.support
 
+import java.io.File
 import java.io.Serializable
 
 data class KtLintParams(
     val experimentalRules: Boolean,
     val disabledRules: List<String>,
+    val baselineFile: File?
 ) : Serializable

src/main/kotlin/org/jmailen/gradle/kotlinter/support/LintErrors.kt

@@ -0,0 +1,10 @@
+package org.jmailen.gradle.kotlinter.support
+
+import com.pinterest.ktlint.core.LintError
+
+internal fun List<LintError>.doesNotContain(error: LintError): Boolean = none { it.isSameAs(error) }
+
+private fun LintError.isSameAs(lintError: LintError) =
+    col == lintError.col &&
+        line == lintError.line &&
+        ruleId == lintError.ruleId

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

@@ -6,12 +6,7 @@ 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.PathSensitive
-import org.gradle.api.tasks.PathSensitivity
-import org.gradle.api.tasks.SourceTask
+import org.gradle.api.tasks.*
 import org.gradle.internal.exceptions.MultiCauseException
 import org.gradle.work.FileChange
 import org.gradle.work.Incremental
@@ -20,6 +15,7 @@ import org.jmailen.gradle.kotlinter.KotlinterExtension.Companion.DEFAULT_DISABLE
 import org.jmailen.gradle.kotlinter.KotlinterExtension.Companion.DEFAULT_EXPERIMENTAL_RULES
 import org.jmailen.gradle.kotlinter.support.KtLintParams
 import org.jmailen.gradle.kotlinter.support.findApplicableEditorConfigFiles
+import java.io.File
 
 abstract class ConfigurableKtLintTask(
     projectLayout: ProjectLayout,
@@ -32,6 +28,11 @@ abstract class ConfigurableKtLintTask(
     @Input
     val disabledRules: ListProperty<String> = objectFactory.listProperty(default = DEFAULT_DISABLED_RULES.toList())
 
+    @get:InputFile
+    @get:PathSensitive(PathSensitivity.RELATIVE)
+    @Optional
+    var baseline: File? = null
+
     @get:InputFiles
     @get:PathSensitive(PathSensitivity.RELATIVE)
     @get:Incremental
@@ -43,6 +44,7 @@ abstract class ConfigurableKtLintTask(
     protected fun getKtLintParams(): KtLintParams = KtLintParams(
         experimentalRules = experimentalRules.get(),
         disabledRules = disabledRules.get(),
+        baselineFile = baseline?.let { project.file(it) }
     )
 
     protected fun getChangedEditorconfigFiles(inputChanges: InputChanges) =

src/main/kotlin/org/jmailen/gradle/kotlinter/tasks/lint/LintWorkerAction.kt

@@ -4,17 +4,13 @@ import com.pinterest.ktlint.core.KtLint
 import com.pinterest.ktlint.core.LintError
 import com.pinterest.ktlint.core.Reporter
 import com.pinterest.ktlint.core.RuleProvider
+import com.pinterest.ktlint.core.api.loadBaseline
 import org.gradle.api.logging.Logger
 import org.gradle.api.logging.Logging
 import org.gradle.internal.logging.slf4j.DefaultContextAwareTaskLogger
 import org.gradle.workers.WorkAction
-import org.jmailen.gradle.kotlinter.support.KotlinterError
-import org.jmailen.gradle.kotlinter.support.KtLintParams
-import org.jmailen.gradle.kotlinter.support.LintFailure
-import org.jmailen.gradle.kotlinter.support.defaultRuleSetProviders
+import org.jmailen.gradle.kotlinter.support.*
 import org.jmailen.gradle.kotlinter.support.editorConfigOverride
-import org.jmailen.gradle.kotlinter.support.reporterFor
-import org.jmailen.gradle.kotlinter.support.reporterPathFor
 import org.jmailen.gradle.kotlinter.support.resetEditorconfigCacheIfNeeded
 import org.jmailen.gradle.kotlinter.support.resolveRuleProviders
 import org.jmailen.gradle.kotlinter.tasks.LintTask
@@ -30,6 +26,13 @@ abstract class LintWorkerAction : WorkAction<LintWorkerParameters> {
     private val name: String = parameters.name.get()
     private val ktLintParams: KtLintParams = parameters.ktLintParams.get()
 
+    private val baselineLintErrorsByFile by lazy {
+        ktLintParams.baselineFile?.let { baselineFile ->
+            loadBaseline(baselineFile.absolutePath)
+                .lintErrorsPerFile
+        } ?: emptyMap()
+    }
+
     override fun execute() {
         resetEditorconfigCacheIfNeeded(
             changedEditorconfigFiles = parameters.changedEditorconfigFiles,
@@ -52,14 +55,22 @@ abstract class LintWorkerAction : WorkAction<LintWorkerParameters> {
                         null
                     }
                 }
+                val relativeFilePath = file.path.removePrefix(projectDirectory.path + "/")
+                val fileBaselineErrors = baselineLintErrorsByFile[relativeFilePath] ?: emptyList()
+
                 lintFunc?.invoke(file, ruleSets) { error ->
-                    hasError = true
-                    reporters.onEach { reporter ->
-                        // some reporters want relative paths, some want absolute
-                        val filePath = reporterPathFor(reporter, file, projectDirectory)
-                        reporter.onLintError(filePath, error, false)
+                    if (fileBaselineErrors.doesNotContain(error)) {
+                        hasError = true
+                        reporters.onEach { reporter ->
+                            // some reporters want relative paths, some want absolute
+                            val filePath = reporterPathFor(reporter, file, projectDirectory)
+                            reporter.onLintError(filePath, error, false)
+                        }
+
+                        logger.quiet("${file.path}:${error.line}:${error.col}: Lint error > [${error.ruleId}] ${error.detail}")
+                    } else {
+                        logger.debug("${file.path}:${error.line}:${error.col}: [Found in baseline; ignoring] Lint error > [${error.ruleId}] ${error.detail}")
                     }
-                    logger.quiet("${file.path}:${error.line}:${error.col}: Lint error > [${error.ruleId}] ${error.detail}")
                 }
                 reporters.onEach { it.after(relativePath) }
             }

test-project/build.gradle.kts

@@ -2,3 +2,7 @@ plugins {
     kotlin("jvm") version "1.7.22"
     id("org.jmailen.kotlinter")
 }
+
+kotlinter {
+    baseline = "config/baseline.xml"
+}

test-project/config/baseline.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<baseline version="1.0">
+    <file name="src/main/kotlin/org/jmailen/gradle/kotlinter/sample/EmptyClassBodyClassExcludedByBaseline.kt">
+        <error line="3" column="45" source="no-empty-class-body" />
+    </file>
+</baseline>

test-project/src/main/kotlin/org/jmailen/gradle/kotlinter/sample/EmptyClassBodyClassExcludedByBaseline.kt

@@ -0,0 +1,4 @@
+package org.jmailen.gradle.kotlinter.sample
+
+class EmptyClassBodyClassExcludedByBaseline {
+}