Merge pull request #417 from ReactiveCocoa/producer-never-fix

Precautionary `SignalProducer.never` fix.

Author: andersio

Sources/SignalProducer.swift

@@ -174,7 +174,9 @@ public struct SignalProducer<Value, Error: Swift.Error> {
 
 	/// A producer for a Signal that never sends any events to its observers.
 	public static var never: SignalProducer {
-		return self.init { _ in return }
+		return self.init { observer, lifetime in
+			lifetime.observeEnded { _ = observer }
+		}
 	}
 
 	/// Create a `Signal` from `self`, pass it into the given closure, and start the

Tests/ReactiveSwiftTests/SignalProducerSpec.swift

@@ -282,10 +282,44 @@ class SignalProducerSpec: QuickSpec {
 		}
 
 		describe("SignalProducer.never") {
-			it("should not send any events") {
+			it("should not send any events while still being alive") {
 				let signalProducer = SignalProducer<Int, NSError>.never
 
-				expect(signalProducer).to(sendValue(nil, sendError: nil, complete: false))
+				var numberOfEvents = 0
+				var isDisposed = false
+
+				func scope() -> Disposable {
+					defer {
+						expect(numberOfEvents) == 0
+						expect(isDisposed) == false
+					}
+					return signalProducer.on(disposed: { isDisposed = true }).start { _ in numberOfEvents += 1 }
+				}
+
+				let d = scope()
+				expect(numberOfEvents) == 0
+				expect(isDisposed) == false
+
+				d.dispose()
+				expect(numberOfEvents) == 1
+				expect(isDisposed) == true
+			}
+
+			it("should not send any events while still being alive even if the interrupt handle deinitializes") {
+				let signalProducer = SignalProducer<Int, NSError>.never
+
+				var numberOfEvents = 0
+				var isDisposed = false
+
+				func scope() {
+					signalProducer.on(disposed: { isDisposed = false }).start { _ in numberOfEvents += 1 }
+					expect(numberOfEvents) == 0
+					expect(isDisposed) == false
+				}
+
+				scope()
+				expect(numberOfEvents) == 0
+				expect(isDisposed) == false
 			}
 		}