Improve utils.wait_for()

1) Rename the 'sleep' parameter to 'check_interval' for more clarity;
2) Add another test for the case when update_resource=None (better coverage);
3) Reduce the running time of the method call in the tests.

Change-Id: If2c6770fb18714fc8fbee0ac0493fb02bbdfea08

rally/utils.py

@@ -126,7 +126,8 @@ def import_modules_from_package(package):
             try_append_module(module_name, sys.modules)
 
 
-def wait_for(resource, is_ready, update_resource=None, timeout=60, sleep=1):
+def wait_for(resource, is_ready, update_resource=None, timeout=60,
+             check_interval=1):
     """Waits for the given resource to come into the desired state.
 
     Uses the readiness check function passed as a parameter and (optionally)
@@ -139,13 +140,14 @@ def wait_for(resource, is_ready, update_resource=None, timeout=60, sleep=1):
                           None, no result updating is performed
     :param timeout: Timeout in seconds after which a TimeoutException will be
                     raised
-    :param sleep: Pause in seconds between the two consecutive readiness checks
+    :param check_interval: Interval in seconds between the two consecutive
+                           readiness checks
 
     :returns: The "ready" resource object
     """
     start = time.time()
     while not is_ready(resource):
-        time.sleep(sleep)
+        time.sleep(check_interval)
         if time.time() - start > timeout:
             raise exceptions.TimeoutException()
         if update_resource:

tests/test_utils.py

@@ -160,11 +160,15 @@ class WaitForTestCase(test.NoDBTestCase):
             return obj
 
         resource = object()
-        fake_checker_delayed = get_fake_checker_delayed(seconds=0.5)
+        fake_checker_delayed = get_fake_checker_delayed(seconds=0.3)
 
         loaded_resource = utils.wait_for(resource, fake_checker_delayed,
                                          fake_updater, 1, 0.2)
         self.assertEqual(loaded_resource, resource)
 
+        loaded_resource = utils.wait_for(resource, fake_checker_delayed,
+                                         None, 1, 0.2)
+        self.assertEqual(loaded_resource, resource)
+
         self.assertRaises(exceptions.TimeoutException, utils.wait_for,
                           object(), fake_checker_false, fake_updater, 0.3, 0.1)