[test] Array-family span properties

Author: glessard

test/stdlib/Span/ArraySpanProperties.swift

@@ -0,0 +1,74 @@
+//===--- ArraySpanProperties.swift ----------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2025 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
+//
+//===----------------------------------------------------------------------===//
+
+// RUN: %target-run-stdlib-swift
+
+// REQUIRES: executable_test
+
+import StdlibUnittest
+
+var suite = TestSuite("Array-Backed Span Properties")
+defer { runAllTests() }
+
+suite.test("Array.span property")
+.skip(.custom(
+  { if #available(SwiftStdlib 6.2, *) { false } else { true } },
+  reason: "Requires Swift 6.2's standard library"
+))
+.code {
+  guard #available(SwiftStdlib 6.2, *) else { return }
+
+  let capacity = 4
+  let a = Array(0..<capacity)
+  let span = a.span
+  expectEqual(span.count, capacity)
+  expectEqual(span[0], a[0])
+}
+
+suite.test("ContiguousArray.span property")
+.skip(.custom(
+  { if #available(SwiftStdlib 6.2, *) { false } else { true } },
+  reason: "Requires Swift 6.2's standard library"
+))
+.code {
+  guard #available(SwiftStdlib 6.2, *) else { return }
+
+  let capacity = 4
+  let a = ContiguousArray(0..<capacity)
+  let span = a.span
+  expectEqual(span.count, capacity)
+  expectEqual(span[0], a[0])
+}
+
+suite.test("ArraySlice.span property")
+.skip(.custom(
+  { if #available(SwiftStdlib 6.2, *) { false } else { true } },
+  reason: "Requires Swift 6.2's standard library"
+))
+.code {
+  guard #available(SwiftStdlib 6.2, *) else { return }
+
+  let capacity = 4
+  let a = Array(0..<capacity)
+  let span1 = a.span
+  expectEqual(span1.count, capacity)
+  expectEqual(span1[0], a[0])
+
+  let s = a[...]
+  let span2 = s.span
+  expectEqual(span2.count, capacity)
+  expectEqual(span2[0], a[0])
+
+  let i1 = span1.withUnsafeBufferPointer { Int(bitPattern: $0.baseAddress) }
+  let i2 = span1.withUnsafeBufferPointer { Int(bitPattern: $0.baseAddress) }
+  expectEqual(i1, i2)
+}