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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 func checkEquatable<Instance: Equatable>(
equivalenceClasses: [[Instance]],
maxSamples: Int? = nil,
file: StaticString = #file,
line: UInt = #line
) {
let instances = equivalenceClasses.flatMap { $0 }
let oracle = equivalenceClasses.indices.flatMap { i in repeatElement(i, count: equivalenceClasses[i].count) }
checkEquatable(instances, oracle: { oracle[$0] == oracle[$1] }, file: file, line: line)
}
public func checkEquatable<C: Collection>(
_ instances: C,
oracle: (C.Index, C.Index) -> Bool,
maxSamples: Int? = nil,
file: StaticString = #file,
line: UInt = #line
) where C.Element: Equatable {
let indices = Array(instances.indices)
checkEquatable(
Array(instances),
oracle: { oracle(indices[$0], indices[$1]) },
file: file, line: line)
}
public func checkEquatable<T : Equatable>(
expectedEqual: Bool, _ lhs: T, _ rhs: T,
file: StaticString = #file, line: UInt = #line
) {
checkEquatable(
[lhs, rhs],
oracle: { expectedEqual || $0 == $1 },
file: file, line: line)
}
public func checkEquatable<Instance: Equatable>(
_ instances: [Instance],
oracle: (Int, Int) -> Bool,
maxSamples: Int? = nil,
file: StaticString = #file,
line: UInt = #line
) {
let entry = TestContext.current.push("checkEquatable", file: file, line: line)
defer { TestContext.current.pop(entry) }
// For each index (which corresponds to an instance being tested) track the
// set of equal instances.
var transitivityScoreboard: [Box<Set<Int>>] = instances.map { _ in Box([]) }
withSomeRanges(
"range", in: 0 ..< instances.count - 1, maxSamples: maxSamples
) { range in
let i = range.lowerBound
let j = range.upperBound
if i == j {
expectTrue(oracle(i, i),
"bad oracle: broken reflexivity at index \(i)")
}
let x = instances[i]
let y = instances[j]
let expectedXY = oracle(i, j)
expectEqual(oracle(j, i), expectedXY,
"bad oracle: broken symmetry between indices \(i), \(j)")
let actualXY = (x == y)
let actualYX = (y == x)
expectEqual(
actualXY, expectedXY,
"""
Elements \((expectedXY
? "expected equal, found not equal"
: "expected not equal, found equal")):
lhs (at index \(i)): \(String(reflecting: x))
rhs (at index \(j)): \(String(reflecting: y))
""")
expectEqual(
actualYX, actualXY,
"""
Reflexivity violation:
\(actualXY
? "lhs == rhs but !(rhs == lhs)"
: "!(lhs == rhs) but rhs == lhs")
lhs (at index \(i)): \(String(reflecting: x))
rhs (at index \(j)): \(String(reflecting: y))
""")
// Not-equal must be the inverse of equal.
expectNotEqual(
x != y, actualXY,
"""
`!=` returns the same result as `==`:
lhs (at index \(i)): \(String(reflecting: x))
rhs (at index \(j)): \(String(reflecting: y))
""")
// Check transitivity of the predicate represented by the oracle.
// If we are adding the instance `j` into an equivalence set, check that
// it is equal to every other instance in the set.
if expectedXY && i < j && transitivityScoreboard[i].value.insert(j).inserted {
if transitivityScoreboard[i].value.count == 1 {
transitivityScoreboard[i].value.insert(i)
}
for k in transitivityScoreboard[i].value {
expectTrue(
oracle(j, 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]))
""")
// No need to check equality between actual values, we will check
// them with the checks above.
}
precondition(transitivityScoreboard[j].value.isEmpty)
transitivityScoreboard[j] = transitivityScoreboard[i]
}
}
}
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