JaCoCo Aggregate Coverage Plugin

Creates an aggregate HTML coverage dashboard from the JaCoCo reports of a multi-module Gradle build.

Features

• Aggregates JaCoCo HTML reports from multiple modules.
• Links the summary to each module's detailed report.
• Supports Android and JVM multi-module projects.
• Supports Gradle configuration cache, build cache, and Isolated Projects.

Important

This plugin does not configure JaCoCo or create report tasks. Each participating module must already have a task that generates a JaCoCo HTML report.

Getting started

1. Apply the plugin in the root project

In the root build.gradle.kts:

plugins {
    id("com.azizutku.jacocoaggregatecoverageplugin") version "0.2.0"
}

2. Configure participating modules

In each subproject whose coverage should be included:

plugins {
    id("com.azizutku.jacocoaggregatecoverageplugin")
}

jacocoAggregateReport {
    reportTaskName.set("jacocoTestDebugUnitTestReport")
}

Set reportTaskName to that module's existing JaCoCo HTML report task. The name may differ between modules. A precompiled script convention plugin can use the same jacocoAggregateReport block. In a binary convention plugin (Plugin<Project>), configure the extension through the target project:

import com.azizutku.jacocoaggregatecoverageplugin.extensions.JacocoAggregateReportPluginExtension
import org.gradle.kotlin.dsl.configure

target.pluginManager.apply("com.azizutku.jacocoaggregatecoverageplugin")
target.extensions.configure<JacocoAggregateReportPluginExtension> {
    reportTaskName.set("createDemoDebugCombinedCoverageReport")
}

3. Generate the report

./gradlew aggregateJacocoReports

The selected report task runs in each participating module. The output directory contains:

build/reports/jacocoAggregated/index.html
build/reports/jacocoAggregated/summary.json

index.html is the aggregate dashboard. summary.json is a deterministic, machine-readable summary containing aggregate totals and per-module counters for instructions, branches, complexity, lines, methods, and classes. Every counter provides exact missed, covered, and total values. Module entries also include the Gradle project path and the relative HTML report path. The JSON uses schema version 1; existing fields keep their names, types, and meaning within that version.

Optional configuration

reportTaskName defaults to jacocoTestReport. The block in step 2 can be omitted in modules that use that name.

To change the aggregate output directory in the root project:

jacocoAggregateCoverage {
    aggregatedReportDirectory.set(layout.buildDirectory.dir("reports/allCoverage"))
}

Non-standard report tasks

Standard JacocoReport tasks need no output configuration. Other task types, including Android Gradle Plugin coverage tasks, require their HTML output directory to be registered:

plugins {
    id("com.azizutku.jacocoaggregatecoverageplugin")
}

jacocoAggregateReport {
    reportTaskName.set("createDebugUnitTestCoverageReport")
    register("createDebugUnitTestCoverageReport") {
        htmlOutputLocation.set(layout.buildDirectory.dir("reports/coverage/test/debug"))
    }
}

Compatibility

Version 0.2.x requires Java 17 and is tested with:

• Gradle 8.4 and 9.7.1.
• JaCoCo 0.8.15 HTML reports.
• Android Gradle Plugin 9.4.0 unit-test coverage reports.
• Gradle 9.7.1 Isolated Projects.

The plugin does not pin the JaCoCo version used by the consuming build.

Example aggregated report

Contributing

Contributions are welcome. Feel free to open an issue or submit a pull request.

License

This project is licensed under the MIT License. Generated aggregate reports reuse resources from the JaCoCo reports supplied by the consuming build; those resources remain covered by the Eclipse Public License v2.0. See LICENSE.