Add a Java 8 test on CI

Author: carlosame

.github/workflows/build.yml

@@ -46,3 +46,19 @@ jobs:
       # Build
       - name: Build with Gradle
         run: ./gradlew build
+
+  testOn8:
+    runs-on: ubuntu-latest
+
+    name: Test on Java 8
+
+    steps:
+      - uses: actions/checkout@v5
+      - name: Set up JDK
+        uses: actions/setup-java@v5
+        with:
+          java-version: '21'
+          distribution: 'temurin'
+      # Run tests with Java 8
+      - name: Test with Java 8
+        run: ./gradlew testOn8

build.gradle

@@ -132,6 +132,17 @@ tasks.register('checkLegacyJava') {
 
 classes.finalizedBy checkLegacyJava
 
+tasks.register('testOn8', Test) {
+	description = 'Runs tests on Java 8'
+	dependsOn classes
+	testClassesDirs = testing.suites.test.sources.output.classesDirs
+	classpath = testing.suites.test.sources.runtimeClasspath
+	useJUnitPlatform()
+	javaLauncher = javaToolchains.launcherFor {
+		languageVersion = JavaLanguageVersion.of(8)
+	}
+}
+
 tasks.register('lineEndingConversion', CRLFConvert) {
 	description = 'Convert top-level files to Windows line endings'
 	file "$rootDir/RELEASE_NOTES.md"