Add a producer to emit the current content followed by subsequent changes

Author: dmcrodrigues

Sources/ReactiveArray.swift

@@ -1,6 +1,6 @@
 import Foundation
 import ReactiveSwift
-import enum Result.NoError
+import Result
 
 // MARK: - Changeset
 
@@ -44,6 +44,21 @@ public final class ReactiveArray<Element> {
 
     public let signal: Signal<Changeset<Element>, NoError>
 
+    public var producer: SignalProducer<Changeset<Element>, NoError> {
+        return SignalProducer.attempt { [weak self] () -> Result<Changeset<Element>, NSError> in
+            guard let `self` = self else { return .failure(NSError()) }
+
+            return .success(
+                Changeset(insertions:
+                    self.changes(inserting: self[self.indices], at: Range(self.indices))
+                )
+            )
+
+            }
+            .flatMapError { _ in .empty }
+            .concat(SignalProducer(signal: signal))
+    }
+
     public var capacity: Int {
         return elements.capacity
     }

Tests/ReactiveArrayTests.swift

@@ -506,6 +506,98 @@ class ReactiveArrayTests: XCTestCase {
             ])
         )
     }
+
+    // MARK: - Producer tests
+
+    func test_producer() {
+
+        var changesets: [Changeset<Int>] = []
+
+        let array = ReactiveArray([1, 2, 3])
+
+        array.producer.startWithValues { changesets.append($0) }
+
+        array.append(4)
+
+        array.removeAll()
+
+        let expectedChangesets = [
+            Changeset(
+                insertions: [
+                    Insert(element: 1, at: 0),
+                    Insert(element: 2, at: 1),
+                    Insert(element: 3, at: 2)
+                ]),
+            Changeset(
+                insertions: [
+                    Insert(element: 4, at: 3)
+                ]),
+            Changeset(
+                deletions: [
+                    Remove(element: 1, at: 0),
+                    Remove(element: 2, at: 1),
+                    Remove(element: 3, at: 2),
+                    Remove(element: 4, at: 3)
+                ])
+        ]
+
+        zip(changesets, expectedChangesets).forEach { XCTAssertEqual($0, $1) }
+    }
+
+    func test_producer_with_up_to_date_changes() {
+
+        var changesets: [Changeset<Int>] = []
+
+        let array = ReactiveArray([1, 2, 3])
+
+        let producer = array.producer
+
+        array.append(4)
+
+        producer.startWithValues { changesets.append($0) }
+
+        array.removeAll()
+
+        let expectedChangesets = [
+            Changeset(
+                insertions: [
+                    Insert(element: 1, at: 0),
+                    Insert(element: 2, at: 1),
+                    Insert(element: 3, at: 2),
+                    Insert(element: 4, at: 3)
+                ]),
+            Changeset(
+                deletions: [
+                    Remove(element: 1, at: 0),
+                    Remove(element: 2, at: 1),
+                    Remove(element: 3, at: 2),
+                    Remove(element: 4, at: 3)
+                ])
+        ]
+
+        zip(changesets, expectedChangesets).forEach { XCTAssertEqual($0, $1) }
+    }
+
+    func test_producer_not_retaining_array() {
+
+        let completedExpectation = expectation(description: "Completed expectation")
+
+        var array = ReactiveArray([1, 2, 3]) as Optional
+
+        let producer = array!.producer
+
+        array = nil
+
+        producer
+            .on(completed: {
+                completedExpectation.fulfill()
+            }, value: { _ in
+                XCTAssertFalse(false, "Producer should not send any values") }
+            )
+            .start()
+
+        waitForExpectations(timeout: 1.0, handler: nil)
+    }
 }
 
 // MARK: - Helpers