GetServicePath should perform a scan

chrome/test/pyautolib/pyauto.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """PyAuto: Python Interface to Chromium's Automation Proxy.
 
 PyAuto uses swig to expose Automation Proxy interfaces to Python.
 For complete documentation on the functionality available,
 run pydoc on this file.
@@ skipping 5046 matching lines @@
 
     Returns:
       The SSID of the connected network or None if we're not connected.
     """
     service_list = self.GetNetworkInfo()
     connected_service_path = service_list.get('connected_wifi')
     if 'wifi_networks' in service_list and \
        connected_service_path in service_list['wifi_networks']:
        return service_list['wifi_networks'][connected_service_path]['name']
 
-  def GetServicePath(self, ssid):
+  def GetServicePath(self, ssid, encryption=None, timeout=30):
     """Returns the service path associated with an SSID.
 
     Args:
       ssid: String defining the SSID we are searching for.
+      encryption: Encryption type of the network; either None to return the
+                  first instance of network that matches the ssid, '' for
+                  an empty network, 'PSK', 'WEP' or '8021X'.
+      timeout: Duration to wait for ssid to appear.
 
     Returns:
-      The service path or None if SSID does not exist.
+      The service path or None if SSID does not exist after timeout period.
     """
-    service_list = self.GetNetworkInfo()
-    service_list = service_list.get('wifi_networks', [])
-    for service_path, service_obj in service_list.iteritems():
-      if service_obj['name'] == ssid:
-        return service_path
+    end_time = time.time() + timeout
+    while time.time() < end_time:

[krisr, 2012/08/06 23:39:13]

How fast does this spin?  i.e. are we spiking the CPU and we burn through this
loop or is NetworkScan slow enough we don't own the device?

[stanleyw, 2012/08/07 01:22:13]

Done.

+      service_list = self.GetNetworkInfo().get('wifi_networks', [])
+      for service_path, service_obj in service_list.iteritems():
+        service_encr = 'PSK' if service_obj['encryption'] in ['WPA', 'RSN'] \
+                       else service_obj['encryption']
+
+        if service_obj['name'] == ssid and \
+           (encryption == None or service_encr == encryption):
+          return service_path
+      self.NetworkScan()
     return None
 
   def NetworkScan(self):
     """Causes ChromeOS to scan for available wifi networks.
 
     Blocks until scanning is complete.
 
     Returns:
       The new list of networks obtained from GetNetworkInfo().
 
@@ skipping 1454 matching lines @@
     successful = result.wasSuccessful()
     if not successful:
       pyauto_tests_file = os.path.join(self.TestsDir(), self._tests_filename)
       print >>sys.stderr, 'Tests can be disabled by editing %s. ' \
                           'Ref: %s' % (pyauto_tests_file, _PYAUTO_DOC_URL)
     sys.exit(not successful)
 
 
 if __name__ == '__main__':
   Main()