Remove ReactiveSwift from Workflow public interface

Author: mjohnson12

Package.swift

@@ -24,6 +24,10 @@ let package = Package(
         .singleTargetLibrary("WorkflowUI"),
         .singleTargetLibrary("WorkflowSwiftUI"),
 
+        // MARK: WorkflowUIReactiveSwift
+
+        .singleTargetLibrary("WorkflowUIReactiveSwift"),
+
         // MARK: WorkflowReactiveSwift
 
         .singleTargetLibrary("WorkflowReactiveSwift"),
@@ -68,12 +72,11 @@ let package = Package(
 
         .target(
             name: "Workflow",
-            dependencies: ["ReactiveSwift"],
             path: "Workflow/Sources"
         ),
         .testTarget(
             name: "WorkflowTests",
-            dependencies: ["Workflow"],
+            dependencies: ["ReactiveSwift", "Workflow"],
             path: "Workflow/Tests"
         ),
         .target(
@@ -104,6 +107,19 @@ let package = Package(
             path: "WorkflowUI/Tests"
         ),
 
+        // MARK: WorkflowUIReactiveSwift
+
+        .target(
+            name: "WorkflowUIReactiveSwift",
+            dependencies: ["ReactiveSwift", "Workflow", "WorkflowUI", "ViewEnvironment", "ViewEnvironmentUI"],
+            path: "WorkflowUIReactiveSwift/Sources"
+        ),
+        .testTarget(
+            name: "WorkflowUIReactiveSwiftTests",
+            dependencies: ["WorkflowUIReactiveSwift", "WorkflowReactiveSwift"],
+            path: "WorkflowUIReactiveSwift/Tests"
+        ),
+
         // MARK: WorkflowSwiftUI
 
         .target(

Samples/Project.swift

@@ -159,7 +159,10 @@ let project = Project(
         .unitTest(
             for: "Workflow",
             sources: "../Workflow/Tests/**",
-            dependencies: [.external(name: "Workflow")]
+            dependencies: [
+                .external(name: "ReactiveSwift"),
+                .external(name: "Workflow"),
+            ]
         ),
         .unitTest(
             for: "WorkflowTesting",
@@ -252,6 +255,17 @@ let project = Project(
                 .target(name: "TestAppHost"),
             ]
         ),
+
+        .unitTest(
+            for: "WorkflowUIReactiveSwift",
+            sources: "../WorkflowUIReactiveSwift/Tests/**",
+            dependencies: [
+                .external(name: "WorkflowUIReactiveSwift"),
+                .external(name: "WorkflowUI"),
+                .external(name: "WorkflowReactiveSwift"),
+                .target(name: "TestAppHost"),
+            ]
+        ),
     ],
     schemes: [
         .scheme(

Samples/Workspace.swift

@@ -9,6 +9,7 @@ let workspace = Workspace(
         .workflow("Workflow"),
         .workflow("WorkflowTesting"),
         .workflow("WorkflowUI"),
+        .workflow("WorkflowUIReactiveSwift"),
         .workflow("WorkflowSwiftUI"),
         .workflow("WorkflowSwiftUIMacros"),
         .workflow("WorkflowReactiveSwift"),

Workflow/Sources/ReadOnlyCurrentValueSubject.swift

@@ -0,0 +1,22 @@
+import Combine
+
+public struct ReadOnlyCurrentValueSubject<Output, Failure>: Combine.Publisher where Failure: Error {
+    private let currentValueSubject: CurrentValueSubject<Output, Failure>
+
+    public var value: Output {
+        currentValueSubject.value
+    }
+
+    private init(_ value: Output) {
+        self.currentValueSubject = CurrentValueSubject<Output, Failure>(value)
+    }
+
+    public static func publisher(value: Output) -> (Self, CurrentValueSubject<Output, Failure>) {
+        let publisher = Self(value)
+        return (publisher, publisher.currentValueSubject)
+    }
+
+    public func receive<S>(subscriber: S) where S: Subscriber, Failure == S.Failure, Output == S.Input {
+        currentValueSubject.receive(subscriber: subscriber)
+    }
+}

Workflow/Sources/WorkflowHost.swift

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import ReactiveSwift
+import Combine
 
 /// Defines a type that receives debug information about a running workflow hierarchy.
 public protocol WorkflowDebugger {
@@ -32,16 +32,15 @@ public protocol WorkflowDebugger {
 
 /// Manages an active workflow hierarchy.
 public final class WorkflowHost<WorkflowType: Workflow> {
-    private let (outputEvent, outputEventObserver) = Signal<WorkflowType.Output, Never>.pipe()
-
     // @testable
     let rootNode: WorkflowNode<WorkflowType>
 
-    private let mutableRendering: MutableProperty<WorkflowType.Rendering>
+    private let muableRendering: CurrentValueSubject<WorkflowType.Rendering, Never>
+    private let outputSubject = PassthroughSubject<WorkflowType.Output, Never>()
 
     /// Represents the `Rendering` produced by the root workflow in the hierarchy. New `Rendering` values are produced
     /// as state transitions occur within the hierarchy.
-    public let rendering: Property<WorkflowType.Rendering>
+    public let rendering: ReadOnlyCurrentValueSubject<WorkflowType.Rendering, Never>
 
     /// Context object to pass down to descendant nodes in the tree.
     let context: HostContext
@@ -77,8 +76,8 @@ public final class WorkflowHost<WorkflowType: Workflow> {
             parentSession: nil
         )
 
-        self.mutableRendering = MutableProperty(rootNode.render())
-        self.rendering = Property(mutableRendering)
+        (self.rendering, self.muableRendering) = ReadOnlyCurrentValueSubject.publisher(value: rootNode.render())
+
         rootNode.enableEvents()
 
         debugger?.didEnterInitialState(snapshot: rootNode.makeDebugSnapshot())
@@ -106,10 +105,10 @@ public final class WorkflowHost<WorkflowType: Workflow> {
     }
 
     private func handle(output: WorkflowNode<WorkflowType>.Output) {
-        mutableRendering.value = rootNode.render()
+        muableRendering.send(rootNode.render())
 
         if let outputEvent = output.outputEvent {
-            outputEventObserver.send(value: outputEvent)
+            outputSubject.send(outputEvent)
         }
 
         debugger?.didUpdate(
@@ -120,9 +119,9 @@ public final class WorkflowHost<WorkflowType: Workflow> {
         rootNode.enableEvents()
     }
 
-    /// A signal containing output events emitted by the root workflow in the hierarchy.
-    public var output: Signal<WorkflowType.Output, Never> {
-        outputEvent
+    /// A publisher containing output events emitted by the root workflow in the hierarchy.
+    public var outputPublisher: AnyPublisher<WorkflowType.Output, Never> {
+        outputSubject.eraseToAnyPublisher()
     }
 }
 

Workflow/Tests/AnyWorkflowTests.swift

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import ReactiveSwift
+import Combine
 import XCTest
 @testable import Workflow
 
@@ -40,19 +40,21 @@ public class AnyWorkflowTests: XCTestCase {
         let host = WorkflowHost(workflow: OnOutputWorkflow())
 
         let renderingExpectation = expectation(description: "Waiting for rendering")
-        host.rendering.producer.startWithValues { rendering in
+        let cancellable = host.rendering.sink { rendering in
             if rendering {
                 renderingExpectation.fulfill()
             }
         }
 
         let outputExpectation = expectation(description: "Waiting for output")
-        host.output.observeValues { output in
+        let outputCancellable = host.outputPublisher.sink { output in
             if output {
                 outputExpectation.fulfill()
             }
         }
         wait(for: [renderingExpectation, outputExpectation], timeout: 1)
+        cancellable.cancel()
+        outputCancellable.cancel()
     }
 
     func testOnlyWrapsOnce() {

Workflow/Tests/ConcurrencyTests.swift

@@ -29,7 +29,7 @@ final class ConcurrencyTests: XCTestCase {
         var first = true
         var observedScreen: TestScreen?
 
-        let disposable = host.rendering.signal.observeValues { rendering in
+        let cancellable = host.rendering.sink { rendering in
             if first {
                 expectation.fulfill()
                 first = false
@@ -47,12 +47,10 @@ final class ConcurrencyTests: XCTestCase {
         wait(for: [expectation], timeout: 1.0)
         guard let screen = observedScreen else {
             XCTFail("Screen was not updated.")
-            disposable?.dispose()
             return
         }
         XCTAssertEqual(1, screen.count)
-
-        disposable?.dispose()
+        cancellable.cancel()
     }
 
     // Events emitted between `render` on a workflow and `enableEvents` are queued and will be delivered asynchronously after rendering is updated.
@@ -62,7 +60,7 @@ final class ConcurrencyTests: XCTestCase {
         let renderingExpectation = expectation(description: "Waiting on rendering values.")
         var first = true
 
-        let disposable = host.rendering.signal.observeValues { rendering in
+        let cancellable = host.rendering.dropFirst().sink { rendering in
             if first {
                 first = false
                 // Emit an event when the rendering is first received.
@@ -81,8 +79,7 @@ final class ConcurrencyTests: XCTestCase {
         waitForExpectations(timeout: 1)
 
         XCTAssertEqual(2, host.rendering.value.count)
-
-        disposable?.dispose()
+        cancellable.cancel()
     }
 
     func test_multipleQueuedEvents() {
@@ -91,7 +88,7 @@ final class ConcurrencyTests: XCTestCase {
         let renderingExpectation = expectation(description: "Waiting on rendering values.")
         var renderingValuesCount = 0
 
-        let disposable = host.rendering.signal.observeValues { rendering in
+        let cancellable = host.rendering.dropFirst().sink { rendering in
             if renderingValuesCount == 0 {
                 // Emit two events.
                 rendering.update()
@@ -116,8 +113,7 @@ final class ConcurrencyTests: XCTestCase {
         waitForExpectations(timeout: 1)
 
         XCTAssertEqual(3, host.rendering.value.count)
-
-        disposable?.dispose()
+        cancellable.cancel()
     }
 
     // A `sink` is invalidated after a single action has been received. However, if the next `render` pass uses a sink
@@ -232,7 +228,7 @@ final class ConcurrencyTests: XCTestCase {
         var first = true
 
         let renderingsComplete = expectation(description: "Waiting for renderings")
-        let disposable = host.rendering.signal.observeValues { rendering in
+        let cancellable = host.rendering.dropFirst().sink { rendering in
             if first {
                 first = false
                 rendering.update()
@@ -249,8 +245,7 @@ final class ConcurrencyTests: XCTestCase {
         XCTAssertEqual(2, debugger.snapshots.count)
         XCTAssertEqual("1", debugger.snapshots[0].stateDescription)
         XCTAssertEqual("2", debugger.snapshots[1].stateDescription)
-
-        disposable?.dispose()
+        cancellable.cancel()
     }
 
     func test_childWorkflowsAreSynchronous() {
@@ -318,11 +313,11 @@ final class ConcurrencyTests: XCTestCase {
 
         let renderingExpectation = XCTestExpectation()
         let outputExpectation = XCTestExpectation()
-        let outDisposable = host.output.signal.observeValues { output in
+        let outputCancellable = host.outputPublisher.sink { output in
             outputExpectation.fulfill()
         }
 
-        let disposable = host.rendering.signal.observeValues { rendering in
+        let cancellable = host.rendering.sink { rendering in
             renderingExpectation.fulfill()
         }
 
@@ -337,8 +332,8 @@ final class ConcurrencyTests: XCTestCase {
 
         XCTAssertEqual(101, host.rendering.value.count)
 
-        disposable?.dispose()
-        outDisposable?.dispose()
+        cancellable.cancel()
+        outputCancellable.cancel()
     }
 
     // Since event pipes are reused for the same type, validate that the `AnyWorkflowAction`

Workflow/Tests/StateMutationSinkTests.swift

@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+import Combine
 import ReactiveSwift
 import Workflow
 import XCTest
@@ -35,14 +36,15 @@ final class StateMutationSinkTests: XCTestCase {
         let host = WorkflowHost(workflow: TestWorkflow(value: 100, signal: output))
 
         let gotValueExpectation = expectation(description: "Got expected value")
-        host.rendering.producer.startWithValues { val in
+        let cancellable = host.rendering.sink { val in
             if val == 100 {
                 gotValueExpectation.fulfill()
             }
         }
 
         input.send(value: 100)
         waitForExpectations(timeout: 1, handler: nil)
+        cancellable.cancel()
     }
 
     func test_multipleUpdates() {
@@ -51,7 +53,7 @@ final class StateMutationSinkTests: XCTestCase {
         let gotValueExpectation = expectation(description: "Got expected value")
 
         var values: [Int] = []
-        host.rendering.producer.startWithValues { val in
+        let cancellable = host.rendering.sink { val in
             values.append(val)
             if val == 300 {
                 gotValueExpectation.fulfill()
@@ -63,6 +65,7 @@ final class StateMutationSinkTests: XCTestCase {
         input.send(value: 300)
         XCTAssertEqual(values, [0, 100, 200, 300])
         waitForExpectations(timeout: 1, handler: nil)
+        cancellable.cancel()
     }
 
     fileprivate struct TestWorkflow: Workflow {

Workflow/Tests/SubtreeManagerTests.swift

@@ -14,7 +14,6 @@
  * limitations under the License.
  */
 
-import ReactiveSwift
 import XCTest
 @testable import Workflow
 

Workflow/Tests/WorkflowHostTests.swift

@@ -65,7 +65,7 @@ final class WorkflowHost_EventEmissionTests: XCTestCase {
 
         XCTAssertEqual(initialRendering.eventCount, 0)
 
-        let disposable = host.rendering.signal.observeValues { rendering in
+        let cancellable = host.rendering.dropFirst().sink { rendering in
             XCTAssertEqual(rendering.eventCount, 1)
 
             // emit another event using an old rendering
@@ -78,7 +78,8 @@ final class WorkflowHost_EventEmissionTests: XCTestCase {
 
             observedRenderCount += 1
         }
-        defer { disposable?.dispose() }
+
+        defer { cancellable.cancel() }
 
         // send an event and cause a re-render
         initialRendering.eventHandler()