Merge pull request #2526 from NachoSoto/signal-merge

Implemented Signal.mergeSignals. Fixes #2487

ReactiveCocoa/Swift/Signal.swift

@@ -358,6 +358,21 @@ extension SignalType {
 	}
 }
 
+extension SignalType {
+	/// Merges the given signals into a single `Signal` that will emit all values
+	/// from each of them, and complete when all of them have completed.
+	public static func merge<S: SequenceType where S.Generator.Element == Signal<Value, Error>>(signals: S) -> Signal<Value, Error> {
+		let producer = SignalProducer<Signal<Value, Error>, Error>(values: signals)
+		var result: Signal<Value, Error>!
+
+		producer.startWithSignal { (signal, _) in
+			result = signal.flatten(.Merge)
+		}
+
+		return result
+	}
+}
+
 extension SignalType where Value: SignalProducerType, Error == Value.Error {
 	/// Returns a signal which sends all the values from producer signal emitted from
 	/// `signal`, waiting until each inner producer completes before beginning to

ReactiveCocoaTests/Swift/SignalSpec.swift

@@ -472,7 +472,6 @@ class SignalSpec: QuickSpec {
 				expect(error).to(equal(producerError))
 			}
 		}
-
 
 		describe("filter") {
 			it("should omit values from the signal") {
@@ -496,6 +495,71 @@ class SignalSpec: QuickSpec {
 			}
 		}
 
+		describe("Signal.merge") {
+			it("should emit values from all signals") {
+				let (signal1, observer1) = Signal<Int, NoError>.pipe()
+				let (signal2, observer2) = Signal<Int, NoError>.pipe()
+
+				let mergedSignals = Signal.merge([signal1, signal2])
+
+				var lastValue: Int?
+				mergedSignals.observeNext { lastValue = $0 }
+
+				expect(lastValue).to(beNil())
+
+				observer1.sendNext(1)
+				expect(lastValue) == 1
+
+				observer2.sendNext(2)
+				expect(lastValue) == 2
+
+				observer1.sendNext(3)
+				expect(lastValue) == 3
+			}
+
+			it("should not stop when one signal completes") {
+				let (signal1, observer1) = Signal<Int, NoError>.pipe()
+				let (signal2, observer2) = Signal<Int, NoError>.pipe()
+
+				let mergedSignals = Signal.merge([signal1, signal2])
+
+				var lastValue: Int?
+				mergedSignals.observeNext { lastValue = $0 }
+
+				expect(lastValue).to(beNil())
+
+				observer1.sendNext(1)
+				expect(lastValue) == 1
+
+				observer1.sendCompleted()
+				expect(lastValue) == 1
+
+				observer2.sendNext(2)
+				expect(lastValue) == 2
+			}
+
+			it("should complete when all signals complete") {
+				let (signal1, observer1) = Signal<Int, NoError>.pipe()
+				let (signal2, observer2) = Signal<Int, NoError>.pipe()
+
+				let mergedSignals = Signal.merge([signal1, signal2])
+
+				var completed = false
+				mergedSignals.observeCompleted { completed = true }
+
+				expect(completed) == false
+
+				observer1.sendNext(1)
+				expect(completed) == false
+
+				observer1.sendCompleted()
+				expect(completed) == false
+
+				observer2.sendCompleted()
+				expect(completed) == true
+			}
+		}
+
 		describe("ignoreNil") {
 			it("should forward only non-nil values") {
 				let (signal, observer) = Signal<Int?, NoError>.pipe()