Test store dependency binding (#1620)

* Bind dependencies when constructing test store and when asserting.

* clean up

* clean up;

* feedback

Author: mbrandonw

Sources/ComposableArchitecture/TestStore.swift

@@ -564,8 +564,9 @@ open class TestStore<State, Action, ScopedState, ScopedAction, Environment> {
   ///   - initialState: The state the feature starts in.
   ///   - reducer: The reducer that powers the runtime of the feature.
   public init<Reducer: ReducerProtocol>(
-    initialState: State,
+    initialState: @autoclosure () -> State,
     reducer: Reducer,
+    prepareDependencies: (inout DependencyValues) -> Void = { _ in },
     file: StaticString = #file,
     line: UInt = #line
   )
@@ -576,6 +577,11 @@ open class TestStore<State, Action, ScopedState, ScopedAction, Environment> {
     Action == ScopedAction,
     Environment == Void
   {
+    var dependencies = DependencyValues()
+    dependencies.context = .test
+    prepareDependencies(&dependencies)
+    let initialState = DependencyValues.$_current.withValue(dependencies) { initialState() }
+
     let reducer = TestReducer(Reduce(reducer), initialState: initialState)
     self._environment = .init(wrappedValue: ())
     self.file = file
@@ -585,6 +591,7 @@ open class TestStore<State, Action, ScopedState, ScopedAction, Environment> {
     self.store = Store(initialState: initialState, reducer: reducer)
     self.timeout = 100 * NSEC_PER_MSEC
     self.toScopedState = { $0 }
+    self.dependencies = dependencies
   }
 
   @available(
@@ -1033,7 +1040,9 @@ extension TestStore where ScopedState: Equatable {
     case .on:
       var expectedWhenGivenPreviousState = expected
       if let updateStateToExpectedResult = updateStateToExpectedResult {
-        try updateStateToExpectedResult(&expectedWhenGivenPreviousState)
+        try DependencyValues.$_current.withValue(self.dependencies) {
+          try updateStateToExpectedResult(&expectedWhenGivenPreviousState)
+        }
       }
       expected = expectedWhenGivenPreviousState
 
@@ -1046,7 +1055,9 @@ extension TestStore where ScopedState: Equatable {
     case .off:
       var expectedWhenGivenActualState = actual
       if let updateStateToExpectedResult = updateStateToExpectedResult {
-        try updateStateToExpectedResult(&expectedWhenGivenActualState)
+        try DependencyValues.$_current.withValue(self.dependencies) {
+          try updateStateToExpectedResult(&expectedWhenGivenActualState)
+        }
       }
       expected = expectedWhenGivenActualState
 
@@ -1058,10 +1069,12 @@ extension TestStore where ScopedState: Equatable {
         && expectedWhenGivenActualState == actual
       {
         var expectedWhenGivenPreviousState = current
-        if let modify = updateStateToExpectedResult {
+        if let updateStateToExpectedResult = updateStateToExpectedResult {
           _XCTExpectFailure(strict: false) {
             do {
-              try modify(&expectedWhenGivenPreviousState)
+              try DependencyValues.$_current.withValue(self.dependencies) {
+                try updateStateToExpectedResult(&expectedWhenGivenPreviousState)
+              }
             } catch {
               XCTFail(
                 """
@@ -2059,11 +2072,7 @@ public struct TestStoreTask: Hashable, Sendable {
 
 class TestReducer<State, Action>: ReducerProtocol {
   let base: Reduce<State, Action>
-  var dependencies = { () -> DependencyValues in
-    var dependencies = DependencyValues()
-    dependencies.context = .test
-    return dependencies
-  }()
+  var dependencies = DependencyValues()
   let effectDidSubscribe = AsyncStream<Void>.streamWithContinuation()
   var inFlightEffects: Set<LongLivingEffect> = []
   var receivedActions: [(action: Action, state: State)] = []

Tests/ComposableArchitectureTests/TestStoreTests.swift

@@ -264,4 +264,34 @@ final class TestStoreTests: XCTestCase {
 
     store.send(true) { $0 = 1 }
   }
+
+  func testDependenciesEarlyBinding() async {
+    struct Feature: ReducerProtocol {
+      struct State: Equatable {
+        var count = 0
+        var date: Date
+        init() {
+          @Dependency(\.date.now) var now: Date
+          self.date = now
+        }
+      }
+      func reduce(into state: inout State, action: Void) -> EffectTask<Void> {
+        state.count += 1
+        return .none
+      }
+    }
+
+    let store = TestStore(
+      initialState: Feature.State(),
+      reducer: Feature()
+    ) {
+      $0.date = .constant(Date(timeIntervalSince1970: 1234567890))
+    }
+
+    await store.send(()) {
+      @Dependency(\.date.now) var now: Date
+      $0.count = 1
+      $0.date = now
+    }
+  }
 }