Check for value error caused by no valid files found with files_changed

This causes an infinite loop when in auto-reload
Fix #467
Fix #451
Fix #443

pelican/utils.py

@@ -241,10 +241,14 @@ def files_changed(path, extensions):
                     yield os.stat(os.path.join(root, f)).st_mtime
 
     global LAST_MTIME
-    mtime = max(file_times(path))
-    if mtime > LAST_MTIME:
-        LAST_MTIME = mtime
-        return True
+    try:
+        mtime = max(file_times(path))
+        if mtime > LAST_MTIME:
+            LAST_MTIME = mtime
+            return True
+    except ValueError:
+        logger.info("No files found in path")
+        return False
     return False
 
 

tests/test_utils.py

@@ -74,7 +74,8 @@ class TestUtils(unittest.TestCase):
         self.assertNotIn(fr_article1, index)
 
     def test_files_changed(self):
-        "Test if file changes are correctly detected"
+        """Test if file changes are correctly detected
+        Make sure to handle not getting any files correctly"""
 
         path = os.path.join(os.path.dirname(__file__), 'content')
         filename = os.path.join(path, 'article_with_metadata.rst')
@@ -90,6 +91,18 @@ class TestUtils(unittest.TestCase):
         self.assertEquals(changed, True)
         self.assertAlmostEqual(utils.LAST_MTIME, t, delta=1)
 
+        empty_path = os.path.join(os.path.dirname(__file__), 'empty')
+        try:
+            os.mkdir(empty_path)
+            os.mkdir(os.path.join(empty_path, "empty_folder"))
+            shutil.copy(__file__, empty_path)
+            changed = utils.files_changed(empty_path, 'rst')
+            self.assertFalse(changed)
+        except OSError:
+            self.fail("OSError Exception in test_files_changed test")
+        finally:
+            shutil.rmtree(empty_path, True)
+
     def test_clean_output_dir(self):
         test_directory = os.path.join(os.path.dirname(__file__), 'clean_output')
         content = os.path.join(os.path.dirname(__file__), 'content')