Migrated tests in devtools/build/lib/vfs to JUnit 4.

--
MOS_MIGRATED_REVID=109081842
diff --git a/src/test/java/com/google/devtools/build/lib/vfs/RootedPathTest.java b/src/test/java/com/google/devtools/build/lib/vfs/RootedPathTest.java
index ccf9432..83a7211 100644
--- a/src/test/java/com/google/devtools/build/lib/vfs/RootedPathTest.java
+++ b/src/test/java/com/google/devtools/build/lib/vfs/RootedPathTest.java
@@ -31,7 +31,7 @@
   private Path root;
 
   @Before
-  public void setUp() throws Exception {
+  public final void initializeFileSystem() throws Exception  {
     filesystem = new InMemoryFileSystem(BlazeClock.instance());
     root = filesystem.getRootDirectory();
   }