[test] UTF8Span from inline-stored String instances

Author: glessard

test/stdlib/Span/StringUTF8SpanProperty.swift

@@ -85,3 +85,35 @@ suite.test("Span from Large Native String's Substring")
     expectEqual(span[i], u[i])
   }
 }
+
+suite.test("Span from UTF8Span")
+.require(.stdlib_6_2).code {
+  guard #available(SwiftStdlib 6.2, *) else { return }
+
+  let s = String(200)
+  let utf8span = s.utf8Span
+  let span1 = utf8span.span
+  let utf8view = s.utf8
+  let span2 = utf8view.span
+  expectEqual(span1.count, span2.count)
+  for (i,j) in zip(span1.indices, span2.indices) {
+    expectEqual(span1[i], span2[j])
+  }
+}
+
+suite.test("UTF8Span from Span")
+.require(.stdlib_6_2).code {
+  guard #available(SwiftStdlib 6.2, *) else { return }
+
+  let s = String(200).utf8
+  let span1 = s.span
+  guard let utf8 = expectNotNil(try? UTF8Span(validating: span1)) else { return }
+
+  expectEqual(utf8.count, span1.count)
+  let span2 = utf8.span
+  expectTrue(span1.isIdentical(to: span2))
+  expectEqual(span1.count, span2.count)
+  for (i,j) in zip(span1.indices, span2.indices) {
+    expectEqual(span1[i], span2[j])
+  }
+}