ContentView.swift

import SwiftUI
import Dependencies

private struct TextView: View {
    let title: String
    let text: String

    var body: some View {
        HStack {
            Text(title)
            Spacer()
            Text(text)
        }
        .padding(.horizontal)
    }
}

struct OuterView: View {
    @Dependency(\.text) private var dependenciesText
    @Environment(\.text) private var environmentText

    var body: some View {
        VStack {
            Text("OuterView")
                .font(.title)
            TextView(title: "@Environment", text: environmentText)
            TextView(title: "@Dependency", text: dependenciesText)
            InnerView()
                .padding()
        }
        .background(.cyan)
    }
}

private struct InnerView: View {
    @Dependency(\.text) private var dependenciesText
    @Environment(\.text) private var environmentText
    @StateObject private var model = Model()

    var body: some View {
        VStack {
            Text("InnerView")
                .font(.title)
            TextView(title: "@Environment", text: environmentText)
            TextView(title: "@Dependency", text: dependenciesText)
                .foregroundColor(.red)
            TextView(title: "Model", text: model.depText)
                .foregroundColor(.red)
        }
        .background(.white)
    }

}

class Model: ObservableObject {
    @Dependency(\.text) var depText
}

struct OuterView_Previews: PreviewProvider {
    static var previews: some View {
        withDependencies {
            $0.text = "Injected - withDependencies"
        } operation: {
            OuterView()
                .environment(\.text, "Injected - .environment()")
        }
    }
}

// MARK: - Text Dependency

extension DependencyValues {
    var text: String {
        get { self[TextKey.self] }
        set { self[TextKey.self] = newValue }
    }

    enum TextKey: TestDependencyKey {
        static var liveValue = "N/A"
        static var testValue = "defaultTestValue"
    }
}

extension EnvironmentValues {
    var text: String {
        get { self[TextKey.self] }
        set { self[TextKey.self] = newValue }
    }

    struct TextKey: EnvironmentKey {
        static var defaultValue: String { "@Environment - Default Value" }
    }
}