Make start timeout work properly.

test/test_server.py

@@ -59,9 +59,32 @@ def test_start_error(self):
         server.ping = MagicMock()
         server.ping.return_value = None
         server.adb = MagicMock()
-        with patch("time.sleep"):
+        with patch("time.sleep") as time_sleep_mock, patch("time.time") as time_time_mock:
+            self._current_time = 0
+            time_sleep_mock.side_effect = self._time_sleep
+            time_time_mock.side_effect = lambda: self._current_time
             with self.assertRaises(IOError):
-                server.start()
+                server.start(timeout=1)
+
+    def _time_sleep(self, timeout):
+        self._current_time += timeout
+
+    # Tests that start() timeout works correctly even in case communication
+    # with device takes too long.
+    def test_start_timeout_works_properly(self):
+        server = AutomatorServer()
+        server.push = MagicMock()
+        server.push.return_value = ["bundle.jar", "uiautomator-stub.jar"]
+        server.ping = MagicMock()
+        server.ping.side_effect = lambda: self._time_sleep(100)
+        server.adb = MagicMock()
+        with patch("time.sleep") as time_sleep_mock, patch("time.time") as time_time_mock:
+            self._current_time = 0
+            time_sleep_mock.side_effect = self._time_sleep
+            time_time_mock.side_effect = lambda: self._current_time
+            with self.assertRaises(IOError):
+                server.start(timeout=1)
+            self.assertGreater(100.2, self._current_time)
 
     def test_auto_start(self):
         try:

uiautomator/__init__.py

@@ -474,10 +474,13 @@ def start(self, timeout=5):
         self.uiautomator_process = self.adb.cmd(*cmd)
         self.adb.forward(self.local_port, self.device_port)
 
-        while not self.alive and timeout > 0:
-            time.sleep(0.1)
-            timeout -= 0.1
-        if not self.alive:
+        step_secs = 0.1
+        expiration_time = time.time() + timeout
+        while time.time() < expiration_time:
+            if self.alive:
+                break
+            time.sleep(step_secs)
+        else:
             raise IOError("RPC server not started!")
 
     def ping(self):