Convert buildSrc to JUnit 5

Closes gh-9467

Author: rwinch

buildSrc/build.gradle

@@ -87,13 +87,19 @@ dependencies {
 	implementation 'org.jfrog.buildinfo:build-info-extractor-gradle:4.9.10'
 	implementation 'org.sonarsource.scanner.gradle:sonarqube-gradle-plugin:2.7.1'
 
-	testImplementation 'junit:junit:4.12'
+	testImplementation platform('org.junit:junit-bom:5.7.2')
+	testImplementation "org.junit.jupiter:junit-jupiter-api"
+	testImplementation "org.junit.jupiter:junit-jupiter-params"
+	testImplementation "org.junit.jupiter:junit-jupiter-engine"
 	testImplementation 'org.apache.commons:commons-io:1.3.2'
 	testImplementation 'org.assertj:assertj-core:3.13.2'
-	testImplementation 'org.mockito:mockito-core:3.0.0'
-	testImplementation 'org.spockframework:spock-core:1.3-groovy-2.5'
+	testImplementation 'org.mockito:mockito-core:3.11.2'
+	testImplementation 'org.mockito:mockito-junit-jupiter:3.11.2'
 	testImplementation "com.squareup.okhttp3:mockwebserver:3.14.9"
 }
 
 
-test.onlyIf { !project.hasProperty("buildSrc.skipTests") }
+test {
+	onlyIf { !project.hasProperty("buildSrc.skipTests") }
+	useJUnitPlatform()
+}