Add Waiter to handle threading for tests

Package.swift

@@ -18,7 +18,8 @@ let package = Package(
         )
     ],
     dependencies: [
-        .package(url: "https://github.com/0xLeif/Cache", from: "2.0.0")
+        .package(url: "https://github.com/0xLeif/Cache", from: "2.0.0"),
+        .package(url: "https://github.com/0xLeif/Waiter", from: "1.0.0")
     ],
     targets: [
         .target(
@@ -29,7 +30,10 @@ let package = Package(
         ),
         .testTarget(
             name: "AppStateTests",
-            dependencies: ["AppState"]
+            dependencies: [
+                "AppState",
+                "Waiter"
+            ]
         )
     ]
 )

Sources/AppState/Application/Application+public.swift

@@ -163,10 +163,20 @@ public extension Application {
                 column: column
             )
 
-            shared.cache.set(
-                value: dependency,
-                forKey: dependency.scope.key
-            )
+            let setValue = {
+                shared.cache.set(
+                    value: dependency,
+                    forKey: dependency.scope.key
+                )
+            }
+
+            #if (!os(Linux) && !os(Windows))
+            Task {
+                setValue()
+            }
+            #else
+            setValue()
+            #endif
         }
     }
 
@@ -199,7 +209,7 @@ public extension Application {
         )
 
         var promotions = Application.state(\.dependencyPromotions)
-        promotions.value.append(promotionOverride)
+        promotions.value[String(describing: keyPath)] = promotionOverride
 
         return Application.self
     }

Sources/AppState/Application/Types/Dependency/Application+Dependency.swift

@@ -1,6 +1,6 @@
 extension Application {
-    var dependencyPromotions: State<[DependencyOverride]> {
-        state(initial: [])
+    var dependencyPromotions: State<[String: DependencyOverride]> {
+        state(initial: [:])
     }
 
     /// `Dependency` struct encapsulates dependencies used throughout the app.

Tests/AppStateTests/AppDependencyTests.swift

@@ -1,3 +1,4 @@
+import Waiter
 import XCTest
 @testable import AppState
 
@@ -58,7 +59,7 @@ final class AppDependencyTests: XCTestCase {
         composableService.networking.fetch()
     }
 
-    func testDependency() {
+    func testDependency() async throws {
         Application.promote(\.networking, with: NetworkService())
 
         let networkingOverride = Application.override(\.networking, with: MockNetworking())
@@ -75,6 +76,12 @@ final class AppDependencyTests: XCTestCase {
 
         networkingOverride.cancel()
 
+        try await Waiter.wait(
+            on: Application.shared,
+            for: \.networking,
+            expecting: { $0.value is NetworkService }
+        )
+
         let networkingService = Application.dependency(\.networking)
 
         XCTAssertNotNil(networkingService as? NetworkService)