Add tests for libuv-based watcher

Four possible results of running tests (first three are errors):

- “The change to inotify/file2 was not detected” on line 84: most common
- “Spurious change detected” at line 82 (uncommon, usually fixed by sleeping
  before running test in do_test_for_change)
- “The change to inotify was not detected” in tree watcher test (e.g. from line
  131) (very rare)
- All OK.

tests/test_watcher.py

@@ -2,6 +2,7 @@
 from __future__ import absolute_import, unicode_literals, print_function, division
 
 from powerline.lib.watcher import create_file_watcher, create_tree_watcher, INotifyError
+from powerline.lib.watcher.uv import UvNotFound
 from powerline import get_fallback_logger
 from powerline.lib.monotonic import monotonic
 
@@ -16,6 +17,14 @@ from tests import TestCase, SkipTest
 INOTIFY_DIR = 'inotify' + os.environ.get('PYTHON', '')
 
 
+def clear_dir(dir):
+	for root, dirs, files in list(os.walk(dir, topdown=False)):
+		for f in files:
+			os.remove(os.path.join(root, f))
+		for d in dirs:
+			os.rmdir(os.path.join(root, d))
+
+
 class TestFilesystemWatchers(TestCase):
 	def do_test_for_change(self, watcher, path):
 		st = monotonic()
@@ -30,6 +39,10 @@ class TestFilesystemWatchers(TestCase):
 			w = create_file_watcher(pl=get_fallback_logger(), watcher_type='inotify')
 		except INotifyError:
 			raise SkipTest('This test is not suitable for a stat based file watcher')
+		return self.do_test_file_watcher(w)
+
+	def do_test_file_watcher(self, w):
+		try:
 			f1, f2, f3 = map(lambda x: os.path.join(INOTIFY_DIR, 'file%d' % x), (1, 2, 3))
 			with open(f1, 'wb'):
 				with open(f2, 'wb'):
@@ -69,13 +82,29 @@ class TestFilesystemWatchers(TestCase):
 			self.assertFalse(w(f2), 'Spurious change detected')
 			os.utime(f2, None)
 			self.do_test_for_change(w, f2)
+		finally:
+			clear_dir(INOTIFY_DIR)
+
+	def test_uv_file_watcher(self):
+		try:
+			w = create_file_watcher(pl=get_fallback_logger(), watcher_type='uv')
+		except UvNotFound:
+			raise SkipTest('Pyuv is not available')
+		return self.do_test_file_watcher(w)
 
 	def test_tree_watcher(self):
 		tw = create_tree_watcher(get_fallback_logger())
+		return self.do_test_tree_watcher(tw)
+
+	def do_test_tree_watcher(self, tw):
+		try:
 			subdir = os.path.join(INOTIFY_DIR, 'subdir')
 			os.mkdir(subdir)
+			try:
 				if tw.watch(INOTIFY_DIR).is_dummy:
 					raise SkipTest('No tree watcher available')
+			except UvNotFound:
+				raise SkipTest('Pyuv is not available')
 			self.assertTrue(tw(INOTIFY_DIR))
 			self.assertFalse(tw(INOTIFY_DIR))
 			changed = partial(self.do_test_for_change, tw, INOTIFY_DIR)
@@ -102,6 +131,12 @@ class TestFilesystemWatchers(TestCase):
 			changed()
 			os.rename(f, f + '1')
 			changed()
+		finally:
+			clear_dir(INOTIFY_DIR)
+
+	def test_uv_tree_watcher(self):
+		tw = create_tree_watcher(get_fallback_logger(), 'uv')
+		return self.do_test_tree_watcher(tw)
 
 
 old_cwd = None
@@ -116,11 +151,7 @@ def setUpModule():
 
 def tearDownModule():
 	for d in [INOTIFY_DIR]:
-		for root, dirs, files in list(os.walk(d, topdown=False)):
+		clear_dir(d)
-			for file in files:
-				os.remove(os.path.join(root, file))
-			for dir in dirs:
-				os.rmdir(os.path.join(root, dir))
 		os.rmdir(d)
 	os.chdir(old_cwd)