Fix seed being truncated

Author: x-sheep

README.md

@@ -50,14 +50,14 @@ It's possible that a test only fails on very specific inputs that don't trigger
 PropertyBased will report which input caused the failing case, and which seed was used:
 
 ```
-Failure occured with input 998.
-Add `.fixedSeed("e1050d658e5e03cea3c802ed4196207a")` to the Test to reproduce this issue.
+Failure occured with input 992.
+Add `.fixedSeed("aKPPWDEafU0CGMDYHef/ETcbYUyjWQvRVP1DTNy6qJk=")` to the Test to reproduce this issue.
 ```
 
 You can supply the fixed seed to reproduce the issue every time.
 
 ```swift
-@Test(.fixedSeed("e1050d658e5e03cea3c802ed4196207a"))
+@Test(.fixedSeed("aKPPWDEafU0CGMDYHef/ETcbYUyjWQvRVP1DTNy6qJk="))
 func failsSometimes() async {
   await propertyCheck(input: .int(in: 0...1000)) { n in
     #expect(n < 990)

Sources/PropertyBased/PropertyCheck.swift

@@ -49,14 +49,14 @@ import Testing
 /// The function will report which input caused the failing case, and which seed was used:
 ///
 /// ```
-/// Failure occured with input 998.
-/// Add `.fixedSeed("e1050d658e5e03cea3c802ed4196207a")` to the Test to reproduce this issue.
+/// Failure occured with input 992.
+/// Add `.fixedSeed("aKPPWDEafU0CGMDYHef/ETcbYUyjWQvRVP1DTNy6qJk=")` to the Test to reproduce this issue.
 /// ```
 ///
 /// You can supply the fixed seed to reproduce the issue every time.
 ///
 /// ```swift
-/// @Test(.fixedSeed("e1050d658e5e03cea3c802ed4196207a"))
+/// @Test(.fixedSeed("aKPPWDEafU0CGMDYHef/ETcbYUyjWQvRVP1DTNy6qJk="))
 /// func failsSometimes() async {
 ///   await propertyCheck(input: .int(in: 0...1000)) { n in
 ///     #expect(n < 990)
@@ -93,15 +93,12 @@ public func propertyCheck<each Value>(isolation: isolated (any Actor)? = #isolat
         var rng = fixedRng?.rng ?? Xoshiro()
         var rngCopy = rng
 
-        rng.perturb()
-        
         let foundIssues = await countIssues(isolation: isolation) {
             try await body(repeat (each input).run(using: &rng))
         }
 
         if foundIssues > 0 {
             let seed = rngCopy.currentSeed
-            rngCopy.perturb()
 
             var paramLabels: [String] = []
             for gen in repeat each input {

Sources/PropertyBased/Xoshiro+SeededRandomNumberGenerator.swift

@@ -9,15 +9,6 @@ import Gen
 import Foundation
 
 extension Xoshiro: @retroactive @unchecked Sendable {}
-
-extension Xoshiro {
-    mutating func perturb() {
-        for _ in 0..<10 {
-            _ = next()
-        }
-    }
-}
-
 extension Xoshiro: @retroactive Hashable {
     public static func == (lhs: Xoshiro, rhs: Xoshiro) -> Bool {
         lhs.currentState == rhs.currentState
@@ -35,17 +26,21 @@ extension Xoshiro: SeededRandomNumberGenerator {
     public typealias Seed = String
 
     public init?(seed: String) {
-        guard seed.count == 32,
-              let s1 = UInt64(seed.prefix(8), radix: 16),
-              let s2 = UInt64(seed.dropFirst(8).prefix(8), radix: 16),
-              let s3 = UInt64(seed.dropFirst(16).prefix(8), radix: 16),
-              let s4 = UInt64(seed.dropFirst(24).prefix(8), radix: 16)
+        guard let data = Data(base64Encoded: seed),
+              data.count == MemoryLayout<UInt64>.size * 4
         else { return nil }
 
-        self.init(state: (s1, s2, s3, s4))
+        let state = data.withUnsafeBytes {
+            let pointer = $0.bindMemory(to: UInt64.self)
+            return (pointer[0], pointer[1], pointer[2], pointer[3])
+        }
+        
+        self.init(state: state)
     }
 
     public var currentSeed: String {
-        String(format: "%.8x%.8x%.8x%.8x", currentState.0, currentState.1, currentState.2, currentState.3)
+        let bytes: ContiguousArray = [currentState.0, currentState.1, currentState.2, currentState.3]
+        let data = bytes.withUnsafeBufferPointer { Data(buffer: $0) }
+        return data.base64EncodedString()
     }
 }

Tests/PropertyBasedTests/FixedSeedTests.swift

@@ -35,11 +35,11 @@ import Gen
         }))
     }
 
-    @Test(.fixedSeed("11223344556677889900aabbccddeeff"))
+    @Test(.fixedSeed("4tPCyvymNncnc+napVCI0T4Jc6IYw1lXOQbXlIqyHck="))
     func testIdenticalInputs() async throws {
         let issues = await gatherIssues {
             await propertyCheck(input: .int(in: 0...1000000)) { n in
-                #expect(n == 960927)
+                #expect(n == 480813)
             }
         }
         #expect(issues.count == 1)
@@ -49,13 +49,12 @@ import Gen
     }
 
     @Test func testXoshiro() throws {
-        var rng = try #require(Xoshiro(seed: "532896ad4a02a15e184a6be2ad433acd"))
+        var rng = try #require(Xoshiro(seed: "I9kE/glCt1MIxbFsddPUSiKFAAJBGKPHSre93c+Wz9E="))
 
-        try #require(rng.currentSeed == "532896ad4a02a15e184a6be2ad433acd")
-        rng.perturb()
-        try #require(rng.next() == 4810111524902131809)
-        try #require(rng.next() == 8977626393675964846)
-        try #require(rng.next() == 1239627430587387523)
-        try #require(rng.currentSeed == "68fb55a91e543b7a00c18b38f77fb1b6")
+        try #require(rng.currentSeed == "I9kE/glCt1MIxbFsddPUSiKFAAJBGKPHSre93c+Wz9E=")
+        try #require(rng.next() == 13012537654314612243)
+        try #require(rng.next() == 17010070744160488460)
+        try #require(rng.next() == 15434697293255949747)
+        try #require(rng.currentSeed == "INXoBVnaU+VA/a0Vu3WfVCmT1mBMK0ZrXJb24K4vLVY=")
     }
 }

Tests/PropertyBasedTests/IntegerAdditionTests.swift

@@ -34,5 +34,4 @@ import Gen
             #expect(first == second)
         }
     }
-    
 }