Add a test for environment injection

We had some issues in this code area previously and I'm thinking of refactoring it in attempt to fix #367. Would be great to increase the test coverage here before further refactoring.

Sources/TokamakCore/MountedViews/MountedElement.swift

@@ -34,6 +34,7 @@ enum MountedElementKind {
 
 public class MountedElement<R: Renderer> {
   private var element: MountedElementKind
+  var type: Any.Type { element.type }
 
   public internal(set) var app: _AnyApp {
     get {
@@ -117,20 +118,16 @@ public class MountedElement<R: Renderer> {
     updateEnvironment()
   }
 
-  @discardableResult
-  func updateEnvironment() -> TypeInfo {
-    // swiftlint:disable:next force_try
-    let info = try! typeInfo(of: element.type)
+  func updateEnvironment() {
+    let type = element.type
     switch element {
     case .app:
-      environmentValues = info.injectEnvironment(from: environmentValues, into: &app.app)
+      environmentValues.inject(into: &app.app, type)
     case .scene:
-      environmentValues = info.injectEnvironment(from: environmentValues, into: &scene.scene)
+      environmentValues.inject(into: &scene.scene, type)
     case .view:
-      environmentValues = info.injectEnvironment(from: environmentValues, into: &view.view)
+      environmentValues.inject(into: &view.view, type)
     }
-
-    return info
   }
 
   func mount(
@@ -163,59 +160,62 @@ public class MountedElement<R: Renderer> {
   }
 }
 
-extension TypeInfo {
-  fileprivate func injectEnvironment(
-    from environmentValues: EnvironmentValues,
-    into element: inout Any
-  ) -> EnvironmentValues {
-    var modifiedEnv = environmentValues
+extension EnvironmentValues {
+  mutating func inject(into element: inout Any, _ type: Any.Type) {
+    // swiftlint:disable:next force_try
+    let info = try! typeInfo(of: type)
+
     // swiftlint:disable force_try
     // Extract the view from the AnyView for modification, apply Environment changes:
-    if genericTypes.contains(where: { $0 is EnvironmentModifier.Type }),
-       let modifier = try! property(named: "modifier").get(from: element) as? EnvironmentModifier
+    if info.genericTypes.contains(where: { $0 is EnvironmentModifier.Type }),
+       let modifier = try! info.property(named: "modifier")
+       .get(from: element) as? EnvironmentModifier
     {
-      modifier.modifyEnvironment(&modifiedEnv)
+      modifier.modifyEnvironment(&self)
     }
 
     // Inject @Environment values
     // swiftlint:disable force_cast
     // `DynamicProperty`s can have `@Environment` properties contained in them,
     // so we have to inject into them as well.
-    for dynamicProp in properties.filter({ $0.type is DynamicProperty.Type }) {
+    for dynamicProp in info.properties.filter({ $0.type is DynamicProperty.Type }) {
       let propInfo = try! typeInfo(of: dynamicProp.type)
       var propWrapper = try! dynamicProp.get(from: element) as! DynamicProperty
       for prop in propInfo.properties.filter({ $0.type is EnvironmentReader.Type }) {
         var wrapper = try! prop.get(from: propWrapper) as! EnvironmentReader
-        wrapper.setContent(from: modifiedEnv)
+        wrapper.setContent(from: self)
         try! prop.set(value: wrapper, on: &propWrapper)
       }
       try! dynamicProp.set(value: propWrapper, on: &element)
     }
-    for prop in properties.filter({ $0.type is EnvironmentReader.Type }) {
+    for prop in info.properties.filter({ $0.type is EnvironmentReader.Type }) {
       var wrapper = try! prop.get(from: element) as! EnvironmentReader
-      wrapper.setContent(from: modifiedEnv)
+      wrapper.setContent(from: self)
       try! prop.set(value: wrapper, on: &element)
     }
     // swiftlint:enable force_try
     // swiftlint:enable force_cast
-
-    return modifiedEnv
   }
+}
 
+extension TypeInfo {
   /// Extract all `DynamicProperty` from a type, recursively.
   /// This is necessary as a `DynamicProperty` can be nested.
   /// `EnvironmentValues` can also be injected at this point.
-  func dynamicProperties(_ environment: EnvironmentValues, source: inout Any) -> [PropertyInfo] {
+  func dynamicProperties(
+    _ environment: inout EnvironmentValues,
+    source: inout Any
+  ) -> [PropertyInfo] {
     var dynamicProps = [PropertyInfo]()
     for prop in properties where prop.type is DynamicProperty.Type {
       dynamicProps.append(prop)
       // swiftlint:disable force_try
       let propInfo = try! typeInfo(of: prop.type)
-      _ = propInfo.injectEnvironment(from: environment, into: &source)
+      environment.inject(into: &source, prop.type)
       var extracted = try! prop.get(from: source)
       dynamicProps.append(
         contentsOf: propInfo.dynamicProperties(
-          environment,
+          &environment,
           source: &extracted
         )
       )

Sources/TokamakCore/StackReconciler.swift

@@ -1,4 +1,4 @@
-// Copyright 2018-2020 Tokamak contributors
+// Copyright 2018-2021 Tokamak contributors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -208,11 +208,12 @@ public final class StackReconciler<R: Renderer> {
     body bodyKeypath: ReferenceWritableKeyPath<MountedCompositeElement<R>, Any>,
     result: KeyPath<MountedCompositeElement<R>, (Any) -> T>
   ) -> T {
-    let info = compositeElement.updateEnvironment()
+    compositeElement.updateEnvironment()
+    let info = try! typeInfo(of: compositeElement.type)
 
     var stateIdx = 0
     let dynamicProps = info.dynamicProperties(
-      compositeElement.environmentValues,
+      &compositeElement.environmentValues,
       source: &compositeElement[keyPath: bodyKeypath]
     )
 

Sources/TokamakDOM/DOMRenderer.swift

@@ -24,8 +24,11 @@ extension EnvironmentValues {
   /// Returns default settings for the DOM environment
   static var defaultEnvironment: Self {
     var environment = EnvironmentValues()
+
+    // `.toggleStyle` property is internal
     environment[_ToggleStyleKey] = _AnyToggleStyle(DefaultToggleStyle())
-    environment[_ColorSchemeKey] = .init(matchMediaDarkScheme: matchMediaDarkScheme)
+
+    environment.colorScheme = .init(matchMediaDarkScheme: matchMediaDarkScheme)
     environment._defaultAppStorage = LocalStorage.standard
     _DefaultSceneStorageProvider.default = SessionStorage.standard
 

Sources/TokamakGTK/Views/NavigationView.swift

@@ -20,7 +20,9 @@ protocol GtkStackProtocol {}
 // extension NavigationView: AnyWidget, ParentView, GtkStackProtocol {
 //   var expand: Bool { true }
 
-//   func new(_ application: UnsafeMutablePointer<GtkApplication>) -> UnsafeMutablePointer<GtkWidget> {
+//   func new(
+//     _ application: UnsafeMutablePointer<GtkApplication>
+//   ) -> UnsafeMutablePointer<GtkWidget> {
 //     let box = gtk_box_new(GTK_ORIENTATION_VERTICAL, 0)!
 //     let stack = gtk_stack_new()!
 //     let sidebar = gtk_stack_sidebar_new()!
@@ -77,7 +79,9 @@ extension NavigationLink: ViewDeferredToRenderer {
 }
 
 // extension NavigationLink: AnyWidget, ParentView {
-//   func new(_ application: UnsafeMutablePointer<GtkApplication>) -> UnsafeMutablePointer<GtkWidget> {
+//   func new(
+//     _ application: UnsafeMutablePointer<GtkApplication>
+//   ) -> UnsafeMutablePointer<GtkWidget> {
 //     let btn = gtk_button_new()!
 //     bindAction(to: btn)
 //     return btn
@@ -105,7 +109,9 @@ extension NavigationLink: ViewDeferredToRenderer {
 // }
 
 // extension NavigationLink: AnyWidget, ParentView {
-//   func new(_ application: UnsafeMutablePointer<GtkApplication>) -> UnsafeMutablePointer<GtkWidget> {
+//   func new(
+//     _ application: UnsafeMutablePointer<GtkApplication>
+//   ) -> UnsafeMutablePointer<GtkWidget> {
 //     print("Creating NavLink widget")
 //     let btn = gtk_button_new()!
 //     bindAction(to: btn)

Tests/TokamakTests/EnvironmentTests.swift

@@ -0,0 +1,46 @@
+// Copyright 2021 Tokamak contributors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+import XCTest
+
+@testable import TokamakCore
+
+private struct TestView: View {
+  @Environment(\.colorScheme) var colorScheme
+
+  public var body: some View {
+    EmptyView()
+  }
+}
+
+final class EnvironmentTests: XCTestCase {
+  func testInjection() {
+    var test: Any = TestView()
+    var values = EnvironmentValues()
+    values.colorScheme = .light
+    values.inject(into: &test, TestView.self)
+    // swiftlint:disable:next force_cast
+    XCTAssertEqual((test as! TestView).colorScheme, .light)
+
+    values.colorScheme = .dark
+    values.inject(into: &test, TestView.self)
+    // swiftlint:disable:next force_cast
+    XCTAssertEqual((test as! TestView).colorScheme, .dark)
+
+    let modifier = TestView().colorScheme(.light)
+    var anyModifier: Any = modifier
+
+    values.inject(into: &anyModifier, type(of: modifier))
+    XCTAssertEqual(values.colorScheme, .light)
+  }
+}

Tests/TokamakTests/ReconcilerTests.swift

@@ -20,12 +20,12 @@ import XCTest
 
 @testable import TokamakCore
 
-struct Counter: View {
+private struct Counter: View {
   @State var count: Int
 
   let limit: Int
 
-  @ViewBuilder public var body: some View {
+  public var body: some View {
     if count < limit {
       VStack {
         Button("Increment") { count += 1 }
@@ -37,7 +37,7 @@ struct Counter: View {
   }
 }
 
-extension Text {
+private extension Text {
   var verbatim: String? {
     guard case let .verbatim(text) = storage else { return nil }
     return text