implement test for random assignment respecting osd capacities

tests/test_dataDistribution.py

@@ -74,7 +74,27 @@ class TestDataDistribution(unittest.TestCase):
         self.fail("expect value error!")
 
     def test_random_distribution_respecting_capacities(self):
-        pass
+        # generate some random distributions and check whether they all respect the OSD capacities
+        max_osd_total_folder_size = 0
+        num_osds = 3
+        osd_capacity = 100
+        num_folders = 10
+        folder_size = 20
+
+        for i in range(0, 100):
+            distribution = dataDistribution.DataDistribution()
+            distribution.add_osd_list(create_test_osd_list(num_osds))
+            distribution.add_folders(create_test_folder_list(num_folders, folder_size),
+                                     random_osd_assignment=True,
+                                     ignore_osd_capacities=False,
+                                     osd_information=create_osd_information(num_osds, osd_capacity),
+                                     capacity=osd_capacity_key)
+
+            osds = distribution.get_osd_list()
+            total_folder_sizes = list(map(lambda x: distribution.OSDs[x].total_folder_size, osds))
+            max_osd_total_folder_size = max(max(total_folder_sizes), max_osd_total_folder_size)
+
+        self.assertTrue(max_osd_total_folder_size <= osd_capacity)
 
     def test_round_robin_distribution(self):
         pass