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[test] Update hash avalanche test #15277

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Merged
merged 1 commit into from
Mar 16, 2018
Merged

[test] Update hash avalanche test #15277

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27 changes: 13 additions & 14 deletions validation-test/stdlib/HashingAvalanche.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -8,35 +8,34 @@ import StdlibUnittest

var HashingTestSuite = TestSuite("Hashing")

func avalancheTest(
_ bits: Int,
_ hashUnderTest: @escaping (UInt64) -> UInt64,
func avalancheTest<Input: FixedWidthInteger & UnsignedInteger>(
for type: Input.Type,
_ hashUnderTest: @escaping (Input) -> Int,
_ pValue: Double
) {
typealias Output = Int
let testsInBatch = 100000
let testData = randArray64(testsInBatch)
let testDataHashed = Array(testData.lazy.map { hashUnderTest($0) })
let testData = randArray64(testsInBatch).map { Input(truncatingIfNeeded: $0) }
let testDataHashed = testData.map { hashUnderTest($0) }

for inputBit in 0..<bits {
for inputBit in 0..<Input.bitWidth {
// Using an array here makes the test too slow.
var bitFlips = UnsafeMutablePointer<Int>.allocate(capacity: bits)
for i in 0..<bits {
bitFlips[i] = 0
}
let bitFlips = UnsafeMutablePointer<Int>.allocate(capacity: Output.bitWidth)
bitFlips.initialize(to: 0, count: Output.bitWidth)
for i in testData.indices {
let inputA = testData[i]
let outputA = testDataHashed[i]
let inputB = inputA ^ (1 << UInt64(inputBit))
let outputB = hashUnderTest(inputB)
var delta = outputA ^ outputB
for outputBit in 0..<bits {
for outputBit in 0..<Output.bitWidth {
if delta & 1 == 1 {
bitFlips[outputBit] += 1
}
delta = delta >> 1
}
}
for outputBit in 0..<bits {
for outputBit in 0..<Output.bitWidth {
expectTrue(
chiSquaredUniform2(testsInBatch, bitFlips[outputBit], pValue),
"inputBit: \(inputBit), outputBit: \(outputBit)")
Expand All @@ -48,11 +47,11 @@ func avalancheTest(
// White-box testing: assume that the other N-bit to N-bit mixing functions
// just dispatch to these. (Avalanche test is relatively expensive.)
HashingTestSuite.test("_Hasher.append(UInt64)/avalanche") {
avalancheTest(64, { UInt64(truncatingIfNeeded: _hashValue(for: $0)) }, 0.02)
avalancheTest(for: UInt64.self, _hashValue(for:), 0.02)
}

HashingTestSuite.test("_Hasher.append(UInt32)/avalanche") {
avalancheTest(32, { UInt64(truncatingIfNeeded: _hashValue(for: $0)) }, 0.02)
avalancheTest(for: UInt32.self, _hashValue(for:), 0.02)
}

runAllTests()