Add test for and fix NPE if thread stopped with no file found

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/io/trunk@1002918 13f79535-47bb-0310-9956-ffa450edef68

Author: sebbASF

src/java/org/apache/commons/io/input/Tailer.java

@@ -148,13 +148,14 @@ public void run() {
 
                 if (reader == null) {
                     Thread.sleep(delay);
+                } else {
+                    // The current position in the file
+                    position = end ? file.length() : 0;
+                    last = System.currentTimeMillis();
+                    reader.seek(position);                    
                 }
             }
 
-            // The current position in the file
-            position = end ? file.length() : 0;
-            last = System.currentTimeMillis();
-            reader.seek(position);
 
             while (run) {
 

src/test/org/apache/commons/io/input/TailerTest.java

@@ -110,13 +110,29 @@ private void write(File file, String... lines) throws Exception {
         }
     }
 
+    public void testStopWithNoFile() throws Exception {
+        File file = new File(getTestDirectory(),"nosuchfile");
+        assertFalse("nosuchfile should not exist", file.exists());
+        TestTailerListener listener = new TestTailerListener();
+        int delay = 100;
+        int idle = 50; // allow time for thread to work
+        Tailer tailer = start(file, listener, delay, false);
+        Thread.sleep(idle);
+        tailer.stop();
+        Thread.sleep(delay+idle);
+        assertNull(listener.exception);
+    }
+
     /**
      * Test {@link TailerListener} implementation.
      */
     private static class TestTailerListener extends TailerListenerAdapter {
 
         private final List<String> lines = new ArrayList<String>();
 
+        volatile Exception exception = null;
+        
+        @Override
         public void handle(String line) {
             lines.add(line);
         }
@@ -126,5 +142,9 @@ public List<String> getLines() {
         public void clear() {
             lines.clear();
         }
+        @Override
+        public void handle(Exception e) {
+            exception = e;
+        }
     }
 }