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authorTim Peters <tim.peters@gmail.com>2004-06-01 18:58:04 (GMT)
committerTim Peters <tim.peters@gmail.com>2004-06-01 18:58:04 (GMT)
commit1f4bcf9edd88600ce99cfbeef16bcea810a5826f (patch)
tree450623fd55ddb8efa5986c24ac6ba43a2011cc8b
parent7897ff0d9a026195d0aa54c55117958d29633dcb (diff)
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test_hash(): The test here is different enough from the one in the bug
report that the stats for expected # of collisions are a little higher. Updated comments accordingly.
-rw-r--r--Lib/test/test_tuple.py10
1 files changed, 7 insertions, 3 deletions
diff --git a/Lib/test/test_tuple.py b/Lib/test/test_tuple.py
index a3f40dd..33a6edd 100644
--- a/Lib/test/test_tuple.py
+++ b/Lib/test/test_tuple.py
@@ -49,9 +49,13 @@ class TupleTest(seq_tests.CommonTest):
# should not exhibit cancellation in tuples like (x,(x,y))
# should be distinct from element hashes: hash(x)!=hash((x,))
# This test exercises those cases.
- # For a pure random hash and N=50, the expected number of collisions
- # is 7.3. Here we allow twice that number.
- # Any worse and the hash function is sorely suspect.
+ # For a pure random hash and N=50, the expected number of occupied
+ # buckets when tossing 252,600 balls into 2**32 buckets
+ # is 252,592.6, or about 7.4 expected collisions. The
+ # standard deviation is 2.73. On a box with 64-bit hash
+ # codes, no collisions are expected. Here we accept no
+ # more than 15 collisions. Any worse and the hash function
+ # is sorely suspect.
N=50
base = range(N)