Extend rendezvous hash testing

Author: betatim

binderhub/tests/test_utils.py

@@ -52,9 +52,8 @@ def test_rendezvous_redistribution():
     # making this comparison
     assert 0.31 < n_moved / n_keys < 0.35
     # keys should move from the two original buckets with approximately
-    # equal probability
-    assert abs(from_bucket["b1"] - from_bucket["b2"]) < 10
-
-    # use the standard deviation of the expected number of entries in each
-    # bucket to get an idea for a reasonable (order of magnitude) difference
-    assert abs(start_in["b1"] - start_in["b2"]) < (n_keys/2)**0.5
+    # equal probability. We pick 30 because it is "about right"
+    assert abs(from_bucket["b1"] - from_bucket["b2"]) < 30
+    # the initial distribution of keys should be roughly the same
+    # We pick 30 because it is "about right"
+    assert abs(start_in["b1"] - start_in["b2"]) < 30