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/UnixPathGetParentTest.java b/src/test/java/com/google/devtools/build/lib/vfs/UnixPathGetParentTest.java
index fa83624..db0cad3 100644
--- a/src/test/java/com/google/devtools/build/lib/vfs/UnixPathGetParentTest.java
+++ b/src/test/java/com/google/devtools/build/lib/vfs/UnixPathGetParentTest.java
@@ -37,14 +37,14 @@
   private Path testRoot;
 
   @Before
-  public void setUp() throws Exception {
+  public final void createTestRoot() throws Exception  {
     unixFs = FileSystems.initDefaultAsNative();
     testRoot = unixFs.getPath(TestUtils.tmpDir()).getRelative("UnixPathGetParentTest");
     FileSystemUtils.createDirectoryAndParents(testRoot);
   }
 
   @After
-  public void tearDown() throws Exception {
+  public final void deleteTestRoot() throws Exception  {
     FileSystemUtils.deleteTree(testRoot); // (comment out during debugging)
   }