Add Kover plugin (#1733)

Co-authored-by: Sergey.Shanshin <sergey.shanshin@jetbrains.com>

build.gradle

@@ -23,6 +23,7 @@ buildscript {
                                       "-Xopt-in=kotlinx.serialization.InternalSerializationApi",
                                       "-Xopt-in=kotlin.ExperimentalUnsignedTypes"
     ]
+    ext.koverEnabled = property('kover.enabled') ?: true
 
     /*
     * This property group is used to build kotlinx.serialization against Kotlin compiler snapshot.
@@ -64,6 +65,7 @@ buildscript {
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
         classpath "org.jetbrains.kotlin:kotlin-serialization:$kotlin_version"
         classpath "org.jetbrains.dokka:dokka-gradle-plugin:$dokka_version"
+        classpath "org.jetbrains.kotlinx:kover:$kover_version"
         classpath "org.jetbrains.kotlinx:binary-compatibility-validator:$validator_version"
         classpath "org.jetbrains.kotlinx:kotlinx-knit:$knit_version"
         classpath 'ru.vyarus:gradle-animalsniffer-plugin:1.5.3' // Android API check
@@ -158,7 +160,9 @@ subprojects {
 
 subprojects {
     // Can't be applied to BOM
-    if (project.name == "kotlinx-serialization-bom" || project.name == "benchmark") return
+    if (project.name == "kotlinx-serialization-bom" || project.name == "benchmark" || project.name == "guide") return
+
+    // Animalsniffer setup
     apply plugin: 'ru.vyarus.animalsniffer'
 
     afterEvaluate { // Can be applied only when the project is evaluated
@@ -170,6 +174,9 @@ subprojects {
             signature 'org.codehaus.mojo.signature:java18:1.0@signature'
         }
     }
+
+    // Kover setup
+    apply from: rootProject.file("gradle/kover.gradle")
 }
 
 apply from: rootProject.file('gradle/compiler-version.gradle')

core/build.gradle

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2017-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
  */
 
 apply plugin: 'kotlin-multiplatform'

formats/cbor/build.gradle

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2017-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
  */
 
 apply plugin: 'kotlin-multiplatform'

formats/json/build.gradle

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2017-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
  */
 
 apply plugin: 'kotlin-multiplatform'

formats/properties/build.gradle

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2017-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
  */
 
 apply plugin: 'kotlin-multiplatform'

formats/protobuf/build.gradle

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2017-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
  */
 
 apply plugin: 'java' // Needed for protobuf plugin only

gradle.properties

@@ -18,6 +18,9 @@ native.deploy=
 validator_version=0.7.1
 knit_version=0.2.2
 coroutines_version=1.3.9
+kover_version=0.3.0
+
+kover.enabled=true
 
 kotlin.mpp.enableGranularSourceSetsMetadata=true
 kotlin.mpp.enableCompatibilityMetadataVariant=true

gradle/kover.gradle

@@ -0,0 +1,21 @@
+/*
+ * Copyright 2017-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+apply plugin: 'kover'
+
+tasks.withType(Test) { task ->
+    // Core is mainly uncovered because a lot of serializers are tested with JSON
+    def minPercentage = (project.name.contains("core") || project.name.contains("properties")) ? 50 : 80
+    kover {
+        enabled = rootProject.ext.koverEnabled
+        generateXml = false
+        generateHtml = true
+        htmlReportDir.set(file("${rootProject.buildDir}/kover/${project.name}/html"))
+        verificationRule {
+            name = "Minimal line coverage rate in percents"
+            minValue = minPercentage
+            // valueType is 'COVERED_LINES_PERCENTAGE' by default
+        }
+    }
+}