ErrorHandling.swift

// RUN: %target-run-simple-swift
// REQUIRES: executable_test

//
// Tests for error handling in standard library APIs.
//

import StdlibUnittest
import StdlibCollectionUnittest


var NoisyCount = 0

class Noisy {
  init() { NoisyCount += 1 }
  deinit { NoisyCount -= 1 }
}
enum SillyError : Error { case JazzHands }

var ErrorHandlingTests = TestSuite("ErrorHandling")


ErrorHandlingTests.test("ErrorHandling/withUnsafeMutableBufferPointer restores array on throw") {
  var x = [1, 2, 3]
  do {
    // Check that the array buffer is restored when an error is thrown
    // inside withUnsafeMutableBufferPointer
    try x.withUnsafeMutableBufferPointer { p in
      p[0] = 4
      p[1] = 5
      p[2] = 6

      // FIXME: Seems to have recently regressed
      // Buffer should be swapped out of the original array.
      // expectEqual(x, [])

      throw SillyError.JazzHands
    }
    expectUnreachable()
  } catch {}

  // Mutated buffer should be restored to the array.
  expectEqual(x, [4, 5, 6])
}

ErrorHandlingTests.test("ErrorHandling/withUnsafeBufferPointer extends lifetime") {
  let initialCount = NoisyCount
  do {
    let x = [Noisy(), Noisy(), Noisy()]
    let countBeforeWithUBP = NoisyCount
    do {
      // Don't use x anywhere in this test after this point.
      try x.withUnsafeBufferPointer { p in
        expectEqual(NoisyCount, countBeforeWithUBP)
        throw SillyError.JazzHands
      }
      expectUnreachable()
    } catch {}
  }
  expectEqual(NoisyCount, initialCount)
}

ErrorHandlingTests.test("ErrorHandling/Optional.map and .flatMap") {
  let x: Int? = 222

  do {
    let _: String? = try x.map {(n: Int) -> String in
      throw SillyError.JazzHands
      return "\(n)"
    }
    expectUnreachable()
  } catch {}

  do {
    let _: String? = try x.flatMap {(n: Int) -> String? in
      throw SillyError.JazzHands
      return .some("\(n)")
    }
    expectUnreachable()
  } catch {}
}

ErrorHandlingTests.test("ErrorHandling/withCString extends lifetime") {
  do {
    let x = "ad astra per aspera"
    do {
      // Don't use x anywhere in this test after this point.
      try x.withCString { p in
        expectEqual(p[0], Int8(("a" as UnicodeScalar).value))
        expectEqual(p[1], Int8(("d" as UnicodeScalar).value))
        throw SillyError.JazzHands
      }
      expectUnreachable()
    } catch {}
  }
  // TODO: Some way to check string was deallocated?
}

ErrorHandlingTests.test("ErrorHandling/firstIndex(where:)") {
  do {
    let _: Int? = try [1, 2, 3].firstIndex {
      throw SillyError.JazzHands
      return $0 == $0
    }
    expectUnreachable()
  } catch {}
}

ErrorHandlingTests.test("ErrorHandling/split") {
  do {
    let _: [Substring] = try "foo".split { _ in
      throw SillyError.JazzHands
      return false
    }
    expectUnreachable()
  } catch {}

  do {
    let _: [ArraySlice<Character>]
      = try AnySequence("foo").split { _ in
        throw SillyError.JazzHands
        return false
      }
    expectUnreachable()
  } catch {}
}

ErrorHandlingTests.test("ErrorHandling/forEach") {
  var loopCount = 0
  do {
    try [1, 2, 3].forEach {
      loopCount += 1
      if $0 == 2 {
        throw SillyError.JazzHands
      }
    }
    expectUnreachable()
  } catch {}

  expectEqual(loopCount, 2)
}


ErrorHandlingTests.test("ErrorHandling/Optional flatMap") {
  var loopCount = 0
  do {
    let _: [Int] = try [1, 2, 3].flatMap {
      loopCount += 1
      if $0 == 2 {
        throw SillyError.JazzHands
      }
      return .some($0)
    }
    expectUnreachable()
  } catch {}

  expectEqual(loopCount, 2)
}

ErrorHandlingTests.test("ErrorHandling/Array flatMap") {
  var loopCount = 0
  do {
    let _: [Int] = try [1, 2, 3].flatMap {(x) -> [Int] in
      loopCount += 1
      if x == 2 {
        throw SillyError.JazzHands
      }
      return Array(repeating: x, count: x)
    }
    expectUnreachable()
  } catch {}

  expectEqual(loopCount, 2)
}

ErrorHandlingTests.test("ErrorHandling/min") {
  do {
    let _: Int? = try [1, 2, 3].min { _, _ in
      throw SillyError.JazzHands
      return false
    }
    expectUnreachable()
  } catch {}

  do {
    let _: Int? = try [1, 2, 3].max { _, _ in
      throw SillyError.JazzHands
      return false
    }
    expectUnreachable()
  } catch {}
}

ErrorHandlingTests.test("ErrorHandling/starts(with:)") {
  do {
    let _: Bool = try [1, 2, 3].starts(with: [1, 2]) { _, _ in
      throw SillyError.JazzHands
      return false
    }
    expectUnreachable()
  } catch {}
}

ErrorHandlingTests.test("ErrorHandling/elementsEqual") {
  do {
    let _: Bool = try [1, 2, 3].elementsEqual([1, 2, 3]) { _, _ in
      throw SillyError.JazzHands
      return false
    }
    expectUnreachable()
  } catch {}
}

ErrorHandlingTests.test("ErrorHandling/lexicographicallyPrecedes(_:)") {
  do {
    let _: Bool = try [1, 2, 3].lexicographicallyPrecedes([0, 2, 3]) { _, _ in
      throw SillyError.JazzHands
      return false
    }
    expectUnreachable()
  } catch {}
}

ErrorHandlingTests.test("ErrorHandling/contains") {
  do {
    let _: Bool = try [1, 2, 3].contains { _ in
      throw SillyError.JazzHands
      return false
    }
    expectUnreachable()
  } catch {}
}

ErrorHandlingTests.test("ErrorHandling/reduce") {
  var loopCount = 0
  do {
    let _: Int = try [1, 2, 3, 4, 5].reduce(0) {
      (x: Int, y: Int) -> Int
    in
      loopCount += 1
      let total = x + y
      if total > 5 {
        throw SillyError.JazzHands
      }
      return total
    }
    expectUnreachable()
  } catch {}
  expectEqual(loopCount, 3)
}

func explosiveBoolean() throws -> Bool {
  throw SillyError.JazzHands
}
func explosiveInt() throws -> Int {
  throw SillyError.JazzHands
}

ErrorHandlingTests.test("ErrorHandling/operators") {
  do {
    if try true && explosiveBoolean() {
      expectUnreachable()
    }
    expectUnreachable()
  } catch {}

  do {
    if try false || explosiveBoolean() {
      expectUnreachable()
    }
    expectUnreachable()
  } catch {}

  do {
    if try nil ?? explosiveInt() == 0 {
      expectUnreachable()
    }
    expectUnreachable()
  } catch {}
}

ErrorHandlingTests.test("ErrorHandling/Sequence map") {
  let initialCount = NoisyCount
  for throwAtCount in 0...3 {
    let sequence = MinimalSequence(elements: [1, 2, 3])
    var loopCount = 0
    do {
      let result: [Noisy] = try sequence.map { _ in
        if loopCount == throwAtCount {
          throw SillyError.JazzHands
        }
        loopCount += 1
        return Noisy()
      }
      expectEqual(NoisyCount, initialCount + 3)
      expectEqual(result.count, 3)
    } catch {}
    expectEqual(NoisyCount, initialCount)
  }
}

ErrorHandlingTests.test("ErrorHandling/Sequence filter") {
  let initialCount = NoisyCount
  for condition in [true, false] {
    for throwAtCount in 0...3 {
      let sequence = [Noisy(), Noisy(), Noisy()]
      var loopCount = 0
      do {
        let result: [Noisy] = try sequence.filter { _ in
          if loopCount == throwAtCount {
            throw SillyError.JazzHands
          }
          loopCount += 1
          return condition
        }
        expectEqual(NoisyCount, initialCount + sequence.count)
        expectEqual(result.count, condition ? 3 : 0)
      } catch {}
    }
    expectEqual(NoisyCount, initialCount)
  }
}

ErrorHandlingTests.test("ErrorHandling/Collection map") {
  let initialCount = NoisyCount
  let collection = [1, 2, 3]
  for throwAtCount in 0...3 {
    var loopCount = 0
    do {
      let result: [Noisy] = try collection.map { _ in
        if loopCount == throwAtCount {
          throw SillyError.JazzHands
        }
        loopCount += 1
        return Noisy()
      }
      expectEqual(NoisyCount, initialCount + 3)
      expectEqual(result.count, 3)
    } catch {}
    expectEqual(NoisyCount, initialCount)
  }
}

ErrorHandlingTests.test("ErrorHandling/sort") {
  let collection = Array(1...5)
  forAllPermutations(collection) { sequence in
    for i in 0..<sequence.count {
      var s = sequence
      let throwElment = sequence[i]
      do {
        try s.sort { (a, b) throws -> Bool in
          if b == throwElment {
            throw SillyError.JazzHands
          }
          return a < b
        }
      } catch {}
      //Check no element should lost and added
      expectEqualsUnordered(collection, s)
    }
  }
}

ErrorHandlingTests.test("ErrorHandling/sorted") {
  let collection = Array(1...5)
  forAllPermutations(collection) { sequence in
    for i in 0..<sequence.count {
      let s = sequence
      var thrown = false
      let throwElment = sequence[i]
      var result: [Int] = []
      do {
        result = try s.sorted { (a, b) throws -> Bool in
          if b == throwElment {
            thrown = true
            throw SillyError.JazzHands
          }
          return a < b
        }
      } catch {}
      //Check actual sequence should not mutate
      expectEqualSequence(sequence, s)
      if thrown {
        //Check result should be empty when thrown
        expectEqualSequence([], result)
      } else {
        //Check result should be sorted when not thrown
        expectEqualSequence(collection, result)
      }
    }
  }
}
 
ErrorHandlingTests.test("ErrorHandling/sort") {
  let collection = Array(1...5)
  forAllPermutations(collection) { sequence in
    for i in 0..<sequence.count {
      var s = sequence
      let throwElment = sequence[i]
      do {
        try s.sort { (a, b) throws -> Bool in
          if b == throwElment {
            throw SillyError.JazzHands
          }
          return a < b
        }
      } catch {}
      //Check no element should lost and added
      expectEqualsUnordered(collection, s)
    }
  }
}
 
ErrorHandlingTests.test("ErrorHandling/sorted") {
  let collection = Array(1...5)
  forAllPermutations(collection) { sequence in
    for i in 0..<sequence.count {
      let s = sequence
      var thrown = false
      let throwElment = sequence[i]
      var result: [Int] = []
      do {
        result = try s.sorted { (a, b) throws -> Bool in
          if b == throwElment {
            thrown = true
            throw SillyError.JazzHands
          }
          return a < b
        }
      } catch {}
      //Check actual sequence should not mutate
      expectEqualSequence(sequence, s)
      if thrown {
        //Check result should be empty when thrown
        expectEqualSequence([], result)
      } else {
        //Check result should be sorted when not thrown
        expectEqualSequence(collection, result)
      }
    }
  }
}
 
runAllTests()