Use SPARK_HOME instead of user.dir in ExecutorRunnerTest

core/src/test/scala/org/apache/spark/deploy/worker/ExecutorRunnerTest.scala

@@ -5,10 +5,9 @@ import org.scalatest.FunSuite
 import org.apache.spark.deploy.{ExecutorState, Command, ApplicationDescription}
 
 class ExecutorRunnerTest extends FunSuite {
-
   test("command includes appId") {
     def f(s:String) = new File(s)
-    val sparkHome = sys.props("user.dir")
+    val sparkHome = sys.env("SPARK_HOME")
     val appDesc = new ApplicationDescription("app name", 8, 500, Command("foo", Seq(),Map()),
       sparkHome, "appUiUrl")
     val appId = "12345-worker321-9876"