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(ns clojure.test-clojure.protocols.hash-collisions
(:use clojure.test))
(defprotocol TestProtocolA
(method-a [this] "Test method A"))
(defprotocol TestProtocolB
(method-b [this] "Test method B"))
(deftype TestType1 [])
(deftype TestType2 [])
(deftype TestType3 [])
(deftype TestType4 [])
(deftype TestType5 [])
(deftype TestType6 [])
(deftype TestType7 [])
(deftype TestType8 [])
(deftype TestType9 [])
(deftype TestType10 [])
(deftype TestType11 [])
(deftype TestType12 [])
(deftype TestType13 [])
(deftype TestType14 [])
(deftype TestType15 [])
(def original-hash hash)
(defn colliding-hash
"Mock hash function which returns identical hash codes for the
classes TestType1 and TestType2, normal hashes for everything else."
[x]
(if (or (= x TestType1) (= x TestType2))
999 ;; artificial hash code, to cause a collision
(original-hash x)))
(deftest protocols-with-hash-collisions
(with-redefs [hash colliding-hash]
(extend TestType1 TestProtocolA {:method-a (constantly 1)})
(extend TestType2 TestProtocolA {:method-a (constantly 2)})
(is (= 1 (method-a (TestType1.))))
(is (= 2 (method-a (TestType2.))))))
(defn no-min-hash-in-13-bits
"Mock hash function which returns hash codes for the classes
TestType1 through TestType15 such that they cannot be compressed
into a 13-bit min-hash table. Returns normal hashes for everything
else."
[x]
(cond
(= x TestType1) 1
(= x TestType2) 2
(= x TestType3) 4
(= x TestType4) 8
(= x TestType5) 16
(= x TestType6) 32
(= x TestType7) 64
(= x TestType8) 128
(= x TestType9) 256
(= x TestType10) 512
(= x TestType11) 1024
(= x TestType12) 2048
(= x TestType13) 4096
(= x TestType14) 8192
(= x TestType15) 16384
:else (original-hash x)))
(deftest protocols-with-no-min-hash-in-13-bits
(with-redefs [hash no-min-hash-in-13-bits]
(extend TestType1 TestProtocolB {:method-b (constantly 1)})
(extend TestType2 TestProtocolB {:method-b (constantly 2)})
(extend TestType3 TestProtocolB {:method-b (constantly 3)})
(extend TestType4 TestProtocolB {:method-b (constantly 4)})
(extend TestType5 TestProtocolB {:method-b (constantly 5)})
(extend TestType6 TestProtocolB {:method-b (constantly 6)})
(extend TestType7 TestProtocolB {:method-b (constantly 7)})
(extend TestType8 TestProtocolB {:method-b (constantly 8)})
(extend TestType9 TestProtocolB {:method-b (constantly 9)})
(extend TestType10 TestProtocolB {:method-b (constantly 10)})
(extend TestType11 TestProtocolB {:method-b (constantly 11)})
(extend TestType12 TestProtocolB {:method-b (constantly 12)})
(extend TestType13 TestProtocolB {:method-b (constantly 13)})
(extend TestType14 TestProtocolB {:method-b (constantly 14)})
(extend TestType15 TestProtocolB {:method-b (constantly 15)})
(is (= 1 (method-b (TestType1.))))
(is (= 2 (method-b (TestType2.))))
(is (= 3 (method-b (TestType3.))))
(is (= 4 (method-b (TestType4.))))
(is (= 5 (method-b (TestType5.))))
(is (= 6 (method-b (TestType6.))))
(is (= 7 (method-b (TestType7.))))
(is (= 8 (method-b (TestType8.))))
(is (= 9 (method-b (TestType9.))))
(is (= 10 (method-b (TestType10.))))
(is (= 11 (method-b (TestType11.))))
(is (= 12 (method-b (TestType12.))))
(is (= 13 (method-b (TestType13.))))
(is (= 14 (method-b (TestType14.))))
(is (= 15 (method-b (TestType15.))))))
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