unit: fix NPE in SETXATTR test

mocked vfs should return a valid stat for a file

Acked-by: Olufemi Adeyemi
Target: master

core/src/test/java/org/dcache/nfs/v4/OperationSETXATTRTest.java

@@ -8,14 +8,17 @@ import org.dcache.nfs.v4.xdr.COMPOUND4args;
 import org.dcache.nfs.v4.xdr.nfs_fh4;
 import org.dcache.nfs.v4.xdr.setxattr_option4;
 import org.dcache.nfs.vfs.Inode;
+import org.dcache.nfs.vfs.Stat;
 import org.dcache.nfs.vfs.VirtualFileSystem;
 import org.junit.Before;
 import org.junit.Test;
 
 import static org.dcache.nfs.v4.NfsTestUtils.execute;
 import static org.dcache.nfs.v4.NfsTestUtils.generateRpcCall;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
 
 public class OperationSETXATTRTest {
 
@@ -24,8 +27,23 @@ public class OperationSETXATTRTest {
     private final nfs_fh4 fh = new nfs_fh4(inode.toNfsHandle());
 
     @Before
-    public void setUp() {
+    public void setUp() throws IOException {
         vfs = mock(VirtualFileSystem.class);
+        Stat fileStat = new Stat();
+
+        fileStat.setMode(Stat.S_IFREG | 0755);
+        fileStat.setMTime(System.currentTimeMillis());
+        fileStat.setATime(System.currentTimeMillis());
+        fileStat.setCTime(System.currentTimeMillis());
+        fileStat.setGeneration(1);
+        fileStat.setNlink(2);
+        fileStat.setUid(1);
+        fileStat.setGid(2);
+        fileStat.setDev(1);
+        fileStat.setFileid(1);
+        fileStat.setSize(512);
+
+        when(vfs.getattr(any())).thenReturn(fileStat);
     }
 
     @Test