How do you give each test its own environment without globals, using TestScoping and task locals?

Predict first

Three parallel tests read a task-local region: one in a scoped suite, one with its own scope, one with none. What do they print?

// === Package.swift ===
// swift-tools-version:6.0
import PackageDescription
let package = Package(name: "Lib", targets: [.target(name: "Lib"), .testTarget(name: "LibTests", dependencies: ["Lib"])])
// === Sources/Lib/Lib.swift ===
public func square(_ x: Int) -> Int { x * x }
// === Tests/LibTests/T.swift ===
import Testing
import Foundation
@testable import Lib

enum Env { @TaskLocal static var region = "global" }

struct InRegion: TestTrait, SuiteTrait, TestScoping {
    let region: String
    var isRecursive: Bool { true }
    func provideScope(for test: Test, testCase: Test.Case?, performing function: @Sendable () async throws -> Void) async throws {
        try await Env.$region.withValue(region) { try await function() }
    }
}
@Suite(InRegion(region: "EU")) struct Scoped {
    @Test func sees() async throws { try await Task.sleep(for: .milliseconds(50)); print("SCOPED", Env.region) }
    @Test(InRegion(region: "US")) func overrides() async throws { try await Task.sleep(for: .milliseconds(50)); print("OVERRIDE", Env.region) }
}
@Test func outside() async throws { try await Task.sleep(for: .milliseconds(50)); print("OUTSIDE", Env.region) }

• EU, US and global respectively
• All print global
• All print EU