Get some test coverage on child/parent effect cancellation behavior. (pointfreeco#1970)

* Get some test coverage on child/parent effect cancellation behavior.

* 5.6 fix

* wip

* rename

Author: mbrandonw

ComposableArchitecture.xcworkspace/xcshareddata/swiftpm/Package.resolved

@@ -26,7 +26,7 @@ let package = Package(
     .package(url: "https://github.com/pointfreeco/swift-dependencies", from: "0.2.0"),
     .package(url: "https://github.com/pointfreeco/swift-identified-collections", from: "0.7.0"),
     .package(url: "https://github.com/pointfreeco/swiftui-navigation", from: "0.7.0"),
-    .package(url: "https://github.com/pointfreeco/xctest-dynamic-overlay", from: "0.5.0"),
+    .package(url: "https://github.com/pointfreeco/xctest-dynamic-overlay", from: "0.8.3"),
   ],
   targets: [
     .target(

Package.resolved

@@ -682,6 +682,80 @@ final class StoreTests: XCTestCase {
     await store.send(.tap)?.value
     XCTAssertEqual(store.state.value.count, testStore.state.count)
   }
+
+  #if swift(>=5.7)
+    func testChidlParentEffectCancellation() async throws {
+      struct Child: ReducerProtocol {
+        struct State: Equatable {}
+        enum Action: Equatable {
+          case task
+          case didFinish
+        }
+
+        func reduce(into state: inout State, action: Action) -> EffectTask<Action> {
+          switch action {
+          case .task:
+            return .run { send in await send(.didFinish) }
+          case .didFinish:
+            return .none
+          }
+        }
+      }
+      struct Parent: ReducerProtocol {
+        struct State: Equatable {
+          var count = 0
+          var child: Child.State?
+        }
+        enum Action: Equatable {
+          case child(Child.Action)
+          case delay
+        }
+        @Dependency(\.mainQueue) var mainQueue
+        var body: Reduce<State, Action> {
+          Reduce { state, action in
+            switch action {
+            case .child(.didFinish):
+              state.child = nil
+              return .task {
+                try await self.mainQueue.sleep(for: .seconds(1))
+                return .delay
+              }
+            case .child:
+              return .none
+            case .delay:
+              state.count += 1
+              return .none
+            }
+          }
+          .ifLet(\.child, action: /Action.child) {
+            Child()
+          }
+        }
+      }
+
+      let mainQueue = DispatchQueue.test
+      let store = Store(
+        initialState: Parent.State(child: Child.State()),
+        reducer: Parent()
+      ) {
+        $0.mainQueue = mainQueue.eraseToAnyScheduler()
+      }
+      let viewStore = ViewStore(store)
+
+      let childTask = viewStore.send(.child(.task))
+      try await Task.sleep(nanoseconds: 100_000_000)
+      XCTAssertEqual(viewStore.child, nil)
+
+      await childTask.cancel()
+      await mainQueue.advance(by: 1)
+      try await Task.sleep(nanoseconds: 100_000_000)
+      XCTTODO(
+        """
+        This fails because cancelling a child task will cancel all parent effects too.
+        """)
+      XCTAssertEqual(viewStore.count, 1)
+    }
+  #endif
 }
 
 private struct Count: TestDependencyKey {

Package.swift

@@ -0,0 +1,10 @@
+import XCTest
+
+@available(
+  *,
+  deprecated,
+  message: "This is a test that currently fails but should not in the future."
+)
+func XCTTODO(_ message: String) {
+  XCTExpectFailure(message)
+}