Detect if running in Previews or Unit Test

detect.swift

public extension EnvironmentValues {
    var isPreview: Bool {
        #if DEBUG
        return ProcessInfo.processInfo.environment["XCODE_RUNNING_FOR_PREVIEWS"] == "1"
        #else
        return false
        #endif
    }
    
    var isUnitTest: Bool {
        #if DEBUG
        return ProcessInfo.processInfo.environment["XCTestConfigurationFilePath"] != nil
        #else
        return false
        #endif
    }
}

struct MyView: View {
    @Environment(\.isPreview) var isPreview

    var body: some View {
        Group {
            if isPreview {
                Text("This is a preview!")
            } else {
                Text("This is not a preview!")
            }
        }
    }
}

// Make sure we don't show SwiftUI during Unit Test

import SwiftUI

@main
struct KeepSakeCardsApp: App {
    @Environment(\.isUnitTest) var isUnitTest
    var body: some Scene {
        WindowGroup {
            if !isUnitTest {
                HomeView(client: .live)
            } else {
                EmptyView()
            }
        }
    }
}