chore: add test coverage

app-common/build.gradle.kts

@@ -62,3 +62,8 @@ dependencies {
     testImplementation(projects.feature.account.fake)
     testImplementation(projects.core.testing)
 }
+
+codeCoverage {
+    branchCoverage.set(9)
+    lineCoverage.set(25)
+}

app-k9mail/build.gradle.kts

@@ -5,10 +5,7 @@ plugins {
     id("thunderbird.quality.badging")
 }
 
-val testCoverageEnabled: Boolean by extra
-if (testCoverageEnabled) {
-    apply(plugin = "jacoco")
-}
+val testCoverageEnabled = hasProperty("testCoverageEnabled")
 
 android {
     namespace = "com.fsck.k9"
@@ -100,6 +97,7 @@ android {
 
         debug {
             applicationIdSuffix = ".debug"
+
             enableUnitTestCoverage = testCoverageEnabled
             enableAndroidTestCoverage = testCoverageEnabled
 
@@ -179,3 +177,8 @@ dependencyGuard {
     configuration("fossReleaseRuntimeClasspath")
     configuration("fullReleaseRuntimeClasspath")
 }
+
+codeCoverage {
+    branchCoverage.set(0)
+    lineCoverage.set(25)
+}

app-thunderbird/build.gradle.kts

@@ -5,10 +5,7 @@ plugins {
     id("thunderbird.quality.badging")
 }
 
-val testCoverageEnabled: Boolean by extra
-if (testCoverageEnabled) {
-    apply(plugin = "jacoco")
-}
+val testCoverageEnabled = hasProperty("testCoverageEnabled")
 
 android {
     namespace = "net.thunderbird.android"
@@ -95,6 +92,9 @@ android {
             applicationIdSuffix = ".debug"
             versionNameSuffix = "-SNAPSHOT"
 
+            enableUnitTestCoverage = testCoverageEnabled
+            enableAndroidTestCoverage = testCoverageEnabled
+
             isMinifyEnabled = false
             isShrinkResources = false
             isDebuggable = true
@@ -283,3 +283,8 @@ tasks.register("printConfigurations") {
         }
     }
 }
+
+codeCoverage {
+    branchCoverage.set(0)
+    lineCoverage.set(25)
+}

app-ui-catalog/build.gradle.kts

@@ -40,3 +40,8 @@ dependencies {
     implementation(libs.kotlin.reflect)
     implementation(libs.kotlinx.datetime)
 }
+
+codeCoverage {
+    branchCoverage.set(0)
+    lineCoverage.set(0)
+}

backend/api/build.gradle.kts

@@ -10,3 +10,8 @@ dependencies {
     implementation(projects.feature.mail.folder.api)
     api(projects.mail.common)
 }
+
+codeCoverage {
+    branchCoverage.set(0)
+    lineCoverage.set(0)
+}

backend/demo/build.gradle.kts

@@ -16,6 +16,11 @@ dependencies {
     testImplementation(projects.mail.testing)
 }
 
+codeCoverage {
+    branchCoverage.set(0)
+    lineCoverage.set(0)
+}
+
 tasks.register<UpdateDemoMailbox>("updateDemoMailbox") {
     group = "demo"
     description = "Update mailbox/contents.json from src/main/resources/mailbox contents."

backend/imap/build.gradle.kts

@@ -22,3 +22,8 @@ dependencies {
     testImplementation(projects.backend.testing)
     testImplementation(libs.mime4j.dom)
 }
+
+codeCoverage {
+    branchCoverage.set(45)
+    lineCoverage.set(44)
+}

backend/jmap/build.gradle.kts

@@ -19,3 +19,8 @@ dependencies {
     testImplementation(projects.backend.testing)
     testImplementation(libs.okhttp.mockwebserver)
 }
+
+codeCoverage {
+    branchCoverage.set(33)
+    lineCoverage.set(42)
+}

backend/pop3/build.gradle.kts

@@ -12,3 +12,8 @@ dependencies {
 
     testImplementation(projects.mail.testing)
 }
+
+codeCoverage {
+    branchCoverage.set(0)
+    lineCoverage.set(0)
+}

backend/testing/build.gradle.kts

@@ -11,3 +11,8 @@ dependencies {
     implementation(libs.junit)
     implementation(libs.assertk)
 }
+
+codeCoverage {
+    branchCoverage.set(0)
+    lineCoverage.set(0)
+}

build-plugin/build.gradle.kts

@@ -21,6 +21,10 @@ dependencies {
     implementation(plugin(libs.plugins.dependency.check))
     implementation(plugin(libs.plugins.detekt))
     implementation(plugin(libs.plugins.spotless))
+    implementation(plugin(libs.plugins.kover))
+
+    // Make custom plugins in :plugins available to precompiled convention plugins by classpath
+    implementation(project(":plugins"))
 
     implementation(libs.diff.utils)
     compileOnly(libs.android.tools.common)
@@ -36,6 +40,6 @@ kotlin {
     }
 }
 
-fun plugin(provider: Provider<PluginDependency>) = with(provider.get()) {
+private fun plugin(provider: Provider<PluginDependency>) = with(provider.get()) {
     "$pluginId:$pluginId.gradle.plugin:$version"
 }

build-plugin/plugins/build.gradle.kts

@@ -0,0 +1,35 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
+plugins {
+    `kotlin-dsl`
+}
+
+group = "net.thunderbird.gradle.plugin"
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_17
+    targetCompatibility = JavaVersion.VERSION_17
+}
+tasks.withType<KotlinCompile>().configureEach {
+    compilerOptions {
+        jvmTarget.set(JvmTarget.JVM_17)
+    }
+}
+
+dependencies {
+    compileOnly(plugin(libs.plugins.kover))
+}
+
+gradlePlugin {
+    plugins {
+        register("QualityCodeCoverage") {
+            id = "net.thunderbird.gradle.plugin.quality.coverage"
+            implementationClass = "net.thunderbird.gradle.plugin.quality.coverage.CodeCoveragePlugin"
+        }
+    }
+}
+
+private fun plugin(provider: Provider<PluginDependency>) = with(provider.get()) {
+    "$pluginId:$pluginId.gradle.plugin:$version"
+}

build-plugin/plugins/gradle.properties

@@ -0,0 +1,3 @@
+org.gradle.parallel=true
+org.gradle.caching=true
+org.gradle.configureondemand=true

build-plugin/plugins/src/main/kotlin/net/thunderbird/gradle/plugin/quality/coverage/CodeCoverageExtension.kt

@@ -0,0 +1,37 @@
+package net.thunderbird.gradle.plugin.quality.coverage
+
+import org.gradle.api.provider.Property
+
+internal const val DEFAULT_MIN_BRANCH_COVERAGE = 70
+internal const val DEFAULT_MIN_LINE_COVERAGE = 75
+
+interface CodeCoverageExtension {
+
+    /**
+     * Whether code coverage is disabled.
+     */
+    val disabled: Property<Boolean>
+
+    /**
+     * Minimum required branch coverage in percent (0-100).
+     */
+    val branchCoverage: Property<Int>
+
+    /**
+     * Minimum required line coverage in percent (0-100).
+     */
+    val lineCoverage: Property<Int>
+
+}
+
+internal fun CodeCoverageExtension.initialize() {
+    disabled.convention(false)
+    branchCoverage.convention(DEFAULT_MIN_BRANCH_COVERAGE)
+    lineCoverage.convention(DEFAULT_MIN_LINE_COVERAGE)
+}
+
+internal fun CodeCoverageExtension.finalizeValueOnRead() {
+    disabled.finalizeValueOnRead()
+    branchCoverage.finalizeValueOnRead()
+    lineCoverage.finalizeValueOnRead()
+}

build-plugin/plugins/src/main/kotlin/net/thunderbird/gradle/plugin/quality/coverage/CodeCoveragePlugin.kt

@@ -0,0 +1,103 @@
+package net.thunderbird.gradle.plugin.quality.coverage
+
+import kotlinx.kover.gradle.plugin.KoverGradlePlugin
+import kotlinx.kover.gradle.plugin.dsl.AggregationType
+import kotlinx.kover.gradle.plugin.dsl.CoverageUnit
+import kotlinx.kover.gradle.plugin.dsl.KoverProjectExtension
+import kotlinx.kover.gradle.plugin.dsl.KoverReportFiltersConfig
+import kotlinx.kover.gradle.plugin.dsl.KoverVerificationRulesConfig
+import net.thunderbird.gradle.plugin.quality.coverage.filter.androidFilter
+import net.thunderbird.gradle.plugin.quality.coverage.filter.commonFilter
+import net.thunderbird.gradle.plugin.quality.coverage.filter.composeFilter
+import org.gradle.api.Plugin
+import org.gradle.api.Project
+import org.gradle.kotlin.dsl.apply
+import org.gradle.kotlin.dsl.create
+
+/**
+ * A Gradle plugin that configures code coverage using the Kover plugin.
+ *
+ * It sets up default coverage thresholds and allows for customization via the [CodeCoverageExtension].
+ *
+ * The plugin can be globally disabled using a Gradle property or environment variable:
+ *  - Gradle property: `-PcodeCoverageDisabled=true`
+ *  - Environment variable: `CODE_COVERAGE_DISABLED=true`
+ *
+ * Example usage in a build script:
+ *
+ * ```kotlin
+ * plugins {
+ *    id("net.thunderbird.gradle.plugin.quality.coverage")
+ * }
+ *
+ * codeCoverage {
+ *    disabled.set(false) // Enable or disable coverage
+ *    lineCoverage.set(80) // Set line coverage threshold
+ *    branchCoverage.set(70) // Set branch coverage threshold
+ * }
+ */
+class CodeCoveragePlugin: Plugin<Project> {
+
+    override fun apply(target: Project) {
+        val extension = target.extensions.create<CodeCoverageExtension>("codeCoverage")
+
+        val gradleProperty = target.providers.gradleProperty("codeCoverageDisabled").map { it.toBoolean() }
+        val environmentProperty = target.providers.environmentVariable("CODE_COVERAGE_DISABLED")
+            .map { it.equals("true", ignoreCase = true) }
+        val disabledProvider = environmentProperty.orElse(gradleProperty).orElse(false)
+
+        extension.disabled.convention(disabledProvider)
+
+        extension.initialize()
+        extension.finalizeValueOnRead()
+
+        target.pluginManager.apply(KoverGradlePlugin::class)
+        target.configureKover(extension)
+    }
+
+    private fun Project.configureKover(coverageExtension: CodeCoverageExtension) {
+        extensions.configure<KoverProjectExtension>("kover") {
+            if (coverageExtension.disabled.get()) {
+                disable()
+            }
+
+            // See https://www.jacoco.org/jacoco/
+            useJacoco("0.8.14")
+
+            reports {
+                total {
+                    filters {
+                        commonFilter()
+                        composeFilter()
+                        androidFilter()
+                    }
+                }
+
+                verify {
+                    warningInsteadOfFailure.set(false)
+
+                    applyVerificationRules(coverageExtension)
+                }
+            }
+        }
+    }
+
+    private fun KoverVerificationRulesConfig.applyVerificationRules(coverageExtension: CodeCoverageExtension) {
+        rule("branchCoveragePercentage") {
+            disabled.set(coverageExtension.disabled)
+            bound {
+                minValue.set(coverageExtension.branchCoverage)
+                coverageUnits.set(CoverageUnit.BRANCH)
+                aggregationForGroup.set(AggregationType.COVERED_PERCENTAGE)
+            }
+        }
+        rule("lineCoveragePercentage") {
+            disabled.set(coverageExtension.disabled)
+            bound {
+                minValue.set(coverageExtension.lineCoverage)
+                coverageUnits.set(CoverageUnit.LINE)
+                aggregationForGroup.set(AggregationType.COVERED_PERCENTAGE)
+            }
+        }
+    }
+}

build-plugin/plugins/src/main/kotlin/net/thunderbird/gradle/plugin/quality/coverage/filter/AndroidFilter.kt

@@ -0,0 +1,13 @@
+package net.thunderbird.gradle.plugin.quality.coverage.filter
+
+import kotlinx.kover.gradle.plugin.dsl.KoverReportFiltersConfig
+
+internal fun KoverReportFiltersConfig.androidFilter() {
+    excludes {
+        classes(
+            "*R$*",
+            "*BuildConfig",
+            "*Manifest*",
+        )
+    }
+}

build-plugin/plugins/src/main/kotlin/net/thunderbird/gradle/plugin/quality/coverage/filter/CommonFilter.kt

@@ -0,0 +1,13 @@
+package net.thunderbird.gradle.plugin.quality.coverage.filter
+
+import kotlinx.kover.gradle.plugin.dsl.KoverReportFiltersConfig
+
+internal fun KoverReportFiltersConfig.commonFilter() {
+    excludes {
+        annotatedBy(
+            "*Generated*",
+            "**Generated**",
+            "*Generated",
+        )
+    }
+}

build-plugin/plugins/src/main/kotlin/net/thunderbird/gradle/plugin/quality/coverage/filter/ComposeFilter.kt

@@ -0,0 +1,15 @@
+package net.thunderbird.gradle.plugin.quality.coverage.filter
+
+import kotlinx.kover.gradle.plugin.dsl.KoverReportFiltersConfig
+
+internal fun KoverReportFiltersConfig.composeFilter() {
+    excludes {
+        annotatedBy(
+            "androidx.compose.ui.tooling.preview.Preview",
+            "androidx.compose.ui.tooling.preview.PreviewLightDark",
+            "app.k9mail.core.ui.compose.common.annotation.PreviewDevices",
+            "app.k9mail.core.ui.compose.common.annotation.PreviewDevicesWithBackground",
+            "app.k9mail.core.ui.compose.designsystem.PreviewLightDarkLandscape",
+        )
+    }
+}

build-plugin/settings.gradle.kts

@@ -7,6 +7,7 @@ pluginManagement {
 dependencyResolutionManagement {
     repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
 
+    @Suppress("UnstableApiUsage")
     repositories {
         gradlePluginPortal()
         google()
@@ -19,3 +20,5 @@ dependencyResolutionManagement {
 }
 
 rootProject.name = "build-plugin"
+
+include(":plugins")