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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2024 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
// Loosely adapted from https://github.com/apple/swift/tree/main/stdlib/private/StdlibUnittest
public enum ExpectedComparisonResult: Hashable {
case lt, eq, gt
public func flip() -> ExpectedComparisonResult {
switch self {
case .lt:
return .gt
case .eq:
return .eq
case .gt:
return .lt
}
}
public static func comparing<C: Comparable>(_ left: C, _ right: C) -> Self {
left < right ? .lt
: left > right ? .gt
: .eq
}
}
extension ExpectedComparisonResult: CustomStringConvertible {
public var description: String {
switch self {
case .lt:
return "<"
case .eq:
return "=="
case .gt:
return ">"
}
}
}
public func checkComparable<Instance: Comparable>(
sortedEquivalenceClasses: [[Instance]],
maxSamples: Int? = nil,
file: StaticString = #file, line: UInt = #line
) {
let instances = sortedEquivalenceClasses.flatMap { $0 }
// oracle[i] is the index of the equivalence class that contains instances[i].
let oracle = sortedEquivalenceClasses.indices.flatMap { i in repeatElement(i, count: sortedEquivalenceClasses[i].count) }
checkComparable(
instances,
oracle: {
if oracle[$0] < oracle[$1] { return .lt }
if oracle[$0] > oracle[$1] { return .gt }
return .eq
},
maxSamples: maxSamples,
file: file, line: line)
}
/// Test that the elements of `instances` satisfy the semantic
/// requirements of `Comparable`, using `oracle` to generate comparison
/// expectations from pairs of positions in `instances`.
public func checkComparable<Instances: Collection>(
_ instances: Instances,
oracle: (Instances.Index, Instances.Index) -> ExpectedComparisonResult,
maxSamples: Int? = nil,
file: StaticString = #file, line: UInt = #line
) where Instances.Element: Comparable, Instances.Index == Int {
checkEquatable(
instances,
oracle: { oracle($0, $1) == .eq },
maxSamples: maxSamples,
file: file, line: line)
_checkComparable(
instances,
oracle: oracle,
maxSamples: maxSamples,
file: file, line: line)
}
public func checkComparable<T : Comparable>(
expected: ExpectedComparisonResult,
_ lhs: T, _ rhs: T,
file: StaticString = #file, line: UInt = #line
) {
checkComparable(
[lhs, rhs],
oracle: { [[ .eq, expected], [ expected.flip(), .eq]][$0][$1] },
file: file, line: line)
}
/// Same as `checkComparable(_:oracle:file:line:)` but doesn't check
/// `Equatable` conformance. Useful for preventing duplicate testing.
public func _checkComparable<Instances: Collection>(
_ instances: Instances,
oracle: (Instances.Index, Instances.Index) -> ExpectedComparisonResult,
maxSamples: Int? = nil,
file: StaticString = #file, line: UInt = #line
) where Instances.Element: Comparable, Instances.Index == Int {
let entry = TestContext.current.push("checkComparable", file: file, line: line)
defer { TestContext.current.pop(entry) }
withSomeRanges(
"range", in: 0 ..< instances.count - 1, maxSamples: maxSamples
) { range in
let i = range.lowerBound
let j = range.upperBound
if i == j {
let x = instances[i]
expectFalse(
x < x,
"found 'x < x' at index \(i): \(String(reflecting: x))")
expectFalse(
x > x,
"found 'x > x' at index \(i): \(String(reflecting: x))")
expectTrue(x <= x,
"found 'x <= x' to be false at index \(i): \(String(reflecting: x))")
expectTrue(x >= x,
"found 'x >= x' to be false at index \(i): \(String(reflecting: x))")
} else {
let x = instances[i]
let y = instances[j]
let expected = oracle(i, j)
expectEqual(
expected.flip(), oracle(j, i),
"""
bad oracle: missing antisymmetry:
lhs (at index \(i)): \(String(reflecting: x))
rhs (at index \(j)): \(String(reflecting: y))
""")
expectEqual(
expected == .lt, x < y,
"""
x < y doesn't match oracle
lhs (at index \(i)): \(String(reflecting: x))
rhs (at index \(j)): \(String(reflecting: y))
""")
expectEqual(
expected != .gt, x <= y,
"""
x <= y doesn't match oracle
lhs (at index \(i)): \(String(reflecting: x))
rhs (at index \(j)): \(String(reflecting: y))
""")
expectEqual(
expected != .lt, x >= y,
"""
x >= y doesn't match oracle
lhs (at index \(i)): \(String(reflecting: x))
rhs (at index \(j)): \(String(reflecting: y))
""")
expectEqual(
expected == .gt, x > y,
"""
x > y doesn't match oracle
lhs (at index \(i)): \(String(reflecting: x))
rhs (at index \(j)): \(String(reflecting: y))
""")
withSome("k", in: instances.indices, maxSamples: 10) { k in
let expected2 = oracle(j, k)
if expected == expected2 {
expectEqual(
expected, oracle(i, k),
"""
bad oracle: transitivity violation
x (at index \(i)): \(String(reflecting: x))
y (at index \(j)): \(String(reflecting: y))
z (at index \(k)): \(String(reflecting: instances[k]))
""")
}
}
}
}
}
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