Add scala import stamping test

test/src/main/scala/scalarules/test/scala_import/ScalaImportExposesJarsTest.scala

@@ -1,17 +1,35 @@
 package scalarules.test.scala_import
 
+import java.util.jar.JarFile
+
 import com.google.common.cache.Cache
 import org.apache.commons.lang3.ArrayUtils
-import org.specs2.mutable.SpecificationWithJUnit
+import org.specs2.mutable.SpecWithJUnit
+
+import scala.reflect.{ClassTag, _}
 
-class ScalaImportExposesJarsTest extends SpecificationWithJUnit {
+class ScalaImportExposesJarsTest extends SpecWithJUnit {
 
   "scala_import" should {
     "enable using the jars it exposes" in {
       println(classOf[Cache[String, String]])
       println(classOf[ArrayUtils])
       success
     }
+
+    "stamps jars with a target label" in {
+      val targetLabel = "//test/src/main/scala/scalarules/test/scala_import:guava_and_commons_lang"
+      findTargetLabel[Cache[String, String]] must beSome(targetLabel)
+      findTargetLabel[ArrayUtils] must beSome(targetLabel)
+    }
+  }
+
+  def findTargetLabel[T: ClassTag]: Option[String] = {
+    val file = classTag[T].runtimeClass.getProtectionDomain.getCodeSource.getLocation.getFile
+    val jar = new JarFile(file)
+    val label = jar.getManifest.getMainAttributes.getValue("Target-Label")
+    jar.close()
+    Some(label)
   }
 
 }