aggregating gradle multiproject test results using TestReport - build

Question

I have a project structure that looks like the below. I want to use the TestReport functionality in Gradle to aggregate all the test results to a single directory.
Then I can access all the test results through a single index.html file for ALL subprojects.
How can I accomplish this?
.
|--ProjectA
|--src/test/...
|--build
|--reports
|--tests
|--index.html (testresults)
|--..
|--..
|--ProjectB
|--src/test/...
|--build
|--reports
|--tests
|--index.html (testresults)
|--..
|--..

Answer 1

From Example 4. Creating a unit test report for subprojects in the Gradle User Guide:
subprojects {
apply plugin: 'java'
// Disable the test report for the individual test task
test {
reports.html.enabled = false
}
}
task testReport(type: TestReport) {
destinationDir = file("$buildDir/reports/allTests")
// Include the results from the `test` task in all subprojects
reportOn subprojects*.test
}
Fully working sample is available from samples/testing/testReport in the full Gradle distribution.

Answer 2

In addition to the subprojects block and testReport task suggested by #peter-niederwieser above, I would add another line to the build below those:
tasks('test').finalizedBy(testReport)
That way if you run gradle test (or even gradle build), the testReport task will run after the subproject tests complete. Note that you have to use tasks('test') rather than just test.finalizedBy(...) because the test task doesn't exist in the root project.

Answer 3

If using kotlin Gradle DSL
val testReport = tasks.register<TestReport>("testReport") {
destinationDir = file("$buildDir/reports/tests/test")
reportOn(subprojects.map { it.tasks.findByPath("test") })
subprojects {
tasks.withType<Test> {
useJUnitPlatform()
finalizedBy(testReport)
ignoreFailures = true
testLogging {
events("passed", "skipped", "failed")
}
}
}
And execute gradle testReport. Source How to generate an aggregated test report for all Gradle subprojects

Answer 4

I am posting updated answer on this topic. I am using Gradle 7.5.1.
TestReport task
In short I'm using following script to set up test aggregation form subprojects (based on #Peter's answer):
subprojects {
apply plugin: 'java'
}
task testReport(type: TestReport) {
destinationDir = file("$buildDir/reports/allTests")
// Include the results from the `test` task in all subprojects
testResults.from = subprojects*.test
}
Note that reportOn method is "deprecated" or will be soon and replaced with testResults, while at the same time testResults is still incubating as of 7.5.1.
I got following warning in IDE
The TestReport.reportOn(Object...) method has been deprecated. This is scheduled to be removed in Gradle 8.0.
Hint: subproject*.test is example of star dot notation in groovy that invokes test task on a list of subprojects. Equally would be invocation of subprojects.collect{it.test}
TestReport#reportOn (Gradle API documentation)
TestReport#testResults (Gradle API documentation)
reportOn replacement for gradle 8 (Gradle Forum)
test-report-aggregation plugin
There is also alternative option for aggregating tests (Since Gradle 7.4). One can apply test-report-aggregation plugin.
If your projects already apply java plugin, this means they will come with jvm-test-suite, all you have to do is apply the plugin.
plugins {
id 'test-report-aggregation'
}
Then you will be able to invoke test reports through testSuiteAggregateTestReport task. Personally didn't use the plugin, but I think it makes sense to use it if you have multiple test suites configured with jvm-test-suite.
Example project can be found in https://github.com/gradle-samples/Aggregating-test-results-using-a-standalone-utility-project-Groovy

Answer 5

For 'connectedAndroidTest's there is a approach published by google.(https://developer.android.com/studio/test/command-line.html#RunTestsDevice (Multi-module reports section))
Add the 'android-reporting' Plugin to your projects build.gradle.
apply plugin: 'android-reporting'
Execute the android tests with additional 'mergeAndroidReports' argument. It will merge all test results of the project modules into one report.
./gradlew connectedAndroidTest mergeAndroidReports

Answer 6

FYI, I've solved this problem using the following subprojects config in my root project build.gradle file. This way no extra tasks are needed.
Note: this places each module's output in its own reports/<module_name> folder, so subproject builds don't overwrite each other's results.
subprojects {
// Combine all build results
java {
reporting.baseDir = "${rootProject.buildDir.path}/reports/${project.name}"
}
}
For a default Gradle project, this would result in a folder structure like
build/reports/module_a/tests/test/index.html
build/reports/module_b/tests/test/index.html
build/reports/module_c/tests/test/index.html