Use jOOX to test XML reports

Instead of asserting string subsequences, we select elements and
attributes in the DOM via jOOX which allows for much more expressive
assertions.

dependencies/dependencies.gradle.kts

@@ -33,5 +33,6 @@ dependencies {
 		api("org.mockito:mockito-junit-jupiter:${versions["mockito"]}")
 		api("biz.aQute.bnd:biz.aQute.bndlib:${versions["bnd"]}")
 		api("org.spockframework:spock-core:${versions["spock"]}")
+		api("org.jooq:joox:${versions["joox"]}")
 	}
 }

gradle.properties

@@ -36,6 +36,7 @@ log4j.version=2.13.3
 mockito.version=3.5.0
 slf4j.version=1.7.30
 spock.version=1.3-groovy-2.5
+joox.version=1.6.2
 
 # Tools
 checkstyle.version=8.31

platform-tests/platform-tests.gradle.kts

@@ -21,6 +21,7 @@ dependencies {
 	testImplementation(testFixtures(project(":junit-platform-launcher")))
 	testImplementation(project(":junit-jupiter-engine"))
 	testImplementation("org.apiguardian:apiguardian-api")
+	testImplementation("org.jooq:joox")
 
 	// --- Test run-time dependencies ---------------------------------------------
 	testRuntimeOnly(project(":junit-vintage-engine"))