Fix flakey test (#1364)

* Fix flakey test

* Try something more general

Author: stephencelis

Sources/ComposableArchitecture/TestStore.swift

@@ -267,9 +267,12 @@
           return
             effects
             .handleEvents(
-              receiveSubscription: { [weak self] _ in
+              receiveSubscription: { [effectDidSubscribe = self.effectDidSubscribe, weak self] _ in
                 self?.inFlightEffects.insert(effect)
-                self?.effectDidSubscribe.continuation.yield()
+                Task {
+                  await Task.megaYield()
+                  effectDidSubscribe.continuation.yield()
+                }
               },
               receiveCompletion: { [weak self] _ in self?.inFlightEffects.remove(effect) },
               receiveCancel: { [weak self] in self?.inFlightEffects.remove(effect) }

Tests/ComposableArchitectureTests/ComposableArchitectureTests.swift

@@ -123,11 +123,7 @@ final class ComposableArchitectureTests: XCTestCase {
       case response(Int)
     }
 
-    struct Environment {
-      let fetch: (Int) async -> Int
-    }
-
-    let reducer = Reducer<Int, Action, Environment> { state, action, environment in
+    let reducer = Reducer<Int, Action, Void> { state, action, _ in
       enum CancelID {}
 
       switch action {
@@ -138,7 +134,7 @@ final class ComposableArchitectureTests: XCTestCase {
         state += 1
         return .task { [state] in
           try await mainQueue.sleep(for: .seconds(1))
-          return .response(await environment.fetch(state))
+          return .response(state * state)
         }
         .cancellable(id: CancelID.self)
 
@@ -151,9 +147,7 @@ final class ComposableArchitectureTests: XCTestCase {
     let store = TestStore(
       initialState: 0,
       reducer: reducer,
-      environment: Environment(
-        fetch: { value in value * value }
-      )
+      environment: ()
     )
 
     await store.send(.incr) { $0 = 1 }