Fix replay(1) not emitting the latest value

Sources/Subjects.swift

@@ -124,6 +124,7 @@ public final class ReplaySubject<E: EventType>: ObserverRegister<E>, RawSubjectT
 public final class ReplayOneSubject<E: EventType>: ObserverRegister<E>, RawSubjectType {
 
   private var event: E? = nil
+  private var terminatingEvent: E? = nil
   private let lock = RecursiveLock(name: "ReactiveKit.ReplayOneSubject")
   private var isUpdating = false
 
@@ -135,7 +136,12 @@ public final class ReplayOneSubject<E: EventType>: ObserverRegister<E>, RawSubje
     lock.lock(); defer { lock.unlock() }
     guard !isUpdating else { return }
     isUpdating = true
-    self.event = event
+    if event.isTermination {
+      self.terminatingEvent = event
+    } else {
+      self.event = event
+    }
+
     observers.forEach { $0(event) }
     isUpdating = false
   }
@@ -145,12 +151,15 @@ public final class ReplayOneSubject<E: EventType>: ObserverRegister<E>, RawSubje
       if let event = event {
         observer(event)
       }
+      if let event = terminatingEvent {
+        observer(event)
+      }
       return addObserver(observer)
     }
   }
 
   private var completed: Bool {
-    if let event = event {
+    if let event = terminatingEvent {
       return event.isTermination
     } else {
       return false

Tests/StreamTests.swift

@@ -426,6 +426,32 @@ class StreamTests: XCTestCase {
     XCTAssertEqual(bob.numberOfRuns, 1)
   }
 
+  func testReplayLatest() {
+    let bob = Scheduler()
+    bob.runRemaining()
+
+    let stream = Stream.sequence([1, 2, 3]).executeIn(bob.context)
+    let replayed = stream.replay(1)
+
+    replayed.expectNext([1, 2, 3])
+    replayed.connect()
+    replayed.expectNext([3])
+    XCTAssertEqual(bob.numberOfRuns, 1)
+  }
+
+  func testReplayLatestIfEmpty() {
+    let bob = Scheduler()
+    bob.runRemaining()
+
+    let stream = Stream.sequence([]).executeIn(bob.context)
+    let replayed = stream.replay(1)
+
+    replayed.expectNext([])
+    replayed.connect()
+    replayed.expectNext([])
+    XCTAssertEqual(bob.numberOfRuns, 1)
+  }
+
   func testPublish() {
     let bob = Scheduler()
     bob.runRemaining()