Use unspecified QoS in QueueScheduler when QoS is unspecified (#880)

CHANGELOG.md

@@ -1,6 +1,7 @@
 # master
 *Please add new entries at the top.*
 
+1. Change `QueueScheduler` to use unspecified QoS when QoS parameter is defaulted
 1. Add support for VisionOS (#875, kudos to @NachoSoto)
 1. Fix minimum deployment target of iOS 11 in CocoaPods
 1. Fix CI release git tag push trigger (#869, kudos to @p4checo)

Sources/Scheduler.swift

@@ -363,7 +363,7 @@ public final class QueueScheduler: DateScheduler {
  /// - targeting: (Optional) The queue on which this scheduler's work is
  /// targeted
  public convenience init(
- qos: DispatchQoS = .default,
+ qos: DispatchQoS = .unspecified,
  name: String = "org.reactivecocoa.ReactiveSwift.QueueScheduler",
  targeting targetQueue: DispatchQueue? = nil
  ) {

Tests/ReactiveSwiftTests/SchedulerSpec.swift

@@ -6,6 +6,9 @@
 // Copyright (c) 2014 GitHub. All rights reserved.
 //
 
+#if canImport(Darwin)
+import Darwin.sys.qos
+#endif
 import Dispatch
 import Foundation
 
@@ -261,6 +264,45 @@ class SchedulerSpec: QuickSpec {
  // enough time to ensure that the first timer was actually cancelled.
  expect(count).toEventually(equal(timesToRun))
  }
+
+ it("should propagate QoS values by default") {
+ expect(scheduler.queue.qos).to(equal(.unspecified))
+
+ // qos_class_self() may not be available on non-Darwin
+ // platforms, and it's unclear if QoS propagation is
+ // implemented in an equivalent manner in such contexts,
+ // so we restrict runtime validation tests to Darwin.
+ #if canImport(Darwin)
+ let userInitiatedQueue = DispatchQueue(
+ label: "reactiveswift.tests.user-initiated",
+ qos: .userInitiated
+ )
+ userInitiatedQueue.suspend()
+
+ var initialQoS: qos_class_t?
+ var endQoS: qos_class_t?
+
+ userInitiatedQueue.async {
+ initialQoS = qos_class_self()
+
+ // scheduling should propagate QoS values by default
+ scheduler.schedule {
+ endQoS = qos_class_self()
+ }
+ }
+
+ scheduler.queue.resume()
+ userInitiatedQueue.resume()
+
+ expect(initialQoS).toEventuallyNot(beNil())
+ expect(endQoS).toEventuallyNot(beNil())
+
+ expect(initialQoS).to(equal(QOS_CLASS_USER_INITIATED))
+ expect(endQoS?.rawValue).to(beGreaterThanOrEqualTo(
+ initialQoS?.rawValue
+ ))
+ #endif // canImport(Darwin)
+ }
  }
  }