Add SwiftUI snapshot tests

Snapshots/SwiftUI/.swiftformat

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+--swiftversion 5.2
+--indent 2

Snapshots/SwiftUI/Bookworm/AddBookView.swift

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+//
+//  AddBookView.swift
+//  Bookworm
+//
+//  Created by Nick Lockwood on 29/06/2020.
+//  Copyright © 2020 Nick Lockwood. All rights reserved.
+//
+
+import SwiftUI
+
+struct AddBookView: View {
+  @Environment(\.managedObjectContext) var moc
+  @Environment(\.presentationMode) var presentationMode
+
+  @State private var title = ""
+  @State private var author = ""
+  @State private var rating = 3
+  @State private var genre = "Fantasy"
+  @State private var review = ""
+
+  let genres = ["Fantasy", "Horror", "Kids", "Mystery", "Poetry", "Romance", "Thriller"]
+
+  var body: some View {
+    NavigationView {
+      Form {
+        Section {
+          TextField("Name of book", text: $title)
+          TextField("Author's name", text: $author)
+
+          Picker("Genre", selection: $genre) {
+            ForEach(genres, id: \.self) {
+              Text($0)
+            }
+          }
+        }
+
+        Section {
+          RatingView(rating: $rating)
+          TextField("Write a review", text: $review)
+        }
+
+        Section {
+          Button("Save") {
+            let newBook = Book(context: self.moc)
+            newBook.title = self.title
+            newBook.author = self.author
+            newBook.rating = Int16(self.rating)
+            newBook.genre = self.genre
+            newBook.review = self.review
+            newBook.date = Date()
+
+            try? self.moc.save()
+            self.presentationMode.wrappedValue.dismiss()
+          }
+        }
+      }
+      .navigationBarTitle("Add book")
+    }
+  }
+}
+
+struct AddBookView_Previews: PreviewProvider {
+  static var previews: some View {
+    AddBookView()
+  }
+}

Snapshots/SwiftUI/Bookworm/ContentView.swift

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+//
+//  ContentView.swift
+//  Bookworm
+//
+//  Created by Nick Lockwood on 29/06/2020.
+//  Copyright © 2020 Nick Lockwood. All rights reserved.
+//
+
+import SwiftUI
+
+struct ContentView: View {
+  @Environment(\.managedObjectContext) var moc
+  @FetchRequest(entity: Book.entity(), sortDescriptors: [
+    NSSortDescriptor(keyPath: \Book.title, ascending: true),
+    NSSortDescriptor(keyPath: \Book.author, ascending: true),
+  ]) var books: FetchedResults<Book>
+
+  @State private var showingAddScreen = false
+
+  var body: some View {
+    NavigationView {
+      List {
+        ForEach(books, id: \.self) { book in
+          NavigationLink(destination:
+            DetailView(book: book).environment(\.managedObjectContext, self.moc)
+          ) {
+            EmojiRatingView(rating: book.rating)
+              .font(.largeTitle)
+
+            VStack(alignment: .leading) {
+              Text(book.title ?? "Unknown title")
+                .font(.headline)
+                .foregroundColor(book.rating < 2 ? .red : .primary)
+              Text(book.author ?? "Unknown author")
+                .foregroundColor(.secondary)
+            }
+          }
+        }
+        .onDelete(perform: deleteBooks(at:))
+      }
+      .navigationBarTitle("Bookworm")
+      .navigationBarItems(leading: EditButton(), trailing: Button(action: {
+        self.showingAddScreen.toggle()
+      }) {
+        Image(systemName: "plus")
+      })
+      .sheet(isPresented: $showingAddScreen) {
+        AddBookView().environment(\.managedObjectContext, self.moc)
+      }
+    }
+  }
+
+  func deleteBooks(at offsets: IndexSet) {
+    for offset in offsets {
+      let book = books[offset]
+      moc.delete(book)
+      try? moc.save()
+    }
+  }
+}
+
+struct ContentView_Previews: PreviewProvider {
+  static var previews: some View {
+    ContentView()
+  }
+}

Snapshots/SwiftUI/Bookworm/DetailView.swift

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+//
+//  DetailView.swift
+//  Bookworm
+//
+//  Created by Nick Lockwood on 30/06/2020.
+//  Copyright © 2020 Nick Lockwood. All rights reserved.
+//
+
+import CoreData
+import SwiftUI
+
+struct DetailView: View {
+  let book: Book
+
+  @Environment(\.managedObjectContext) var moc
+  @Environment(\.presentationMode) var presentationMode
+  @State private var showingDeleteAlert = false
+
+  var body: some View {
+    GeometryReader { geo in
+      VStack {
+        ZStack(alignment: .bottomTrailing) {
+          Image(self.book.genre ?? "Fantasy")
+            .frame(maxWidth: geo.size.width)
+
+          Text(self.book.genre?.uppercased() ?? "FANTASY")
+            .font(.caption)
+            .fontWeight(.black)
+            .padding(8)
+            .foregroundColor(.white)
+            .background(Color.black.opacity(0.75))
+            .clipShape(Capsule())
+            .offset(x: -5, y: -5)
+        }
+
+        Text(self.book.author ?? "Unknown author")
+          .font(.title)
+          .foregroundColor(.secondary)
+
+        Text(self.book.review ?? "No review")
+          .padding()
+
+        Text(self.formattedDate(for: self.book))
+          .padding()
+
+        RatingView(rating: .constant(Int(self.book.rating)))
+          .font(.largeTitle)
+
+        Spacer()
+      }
+    }
+    .navigationBarTitle(Text(book.title ?? "Unknown book"), displayMode: .inline)
+    .alert(isPresented: $showingDeleteAlert) {
+      Alert(title: Text("Delete book"), message: Text("Are you sure?"), primaryButton: .destructive(Text("Delete")) {
+        self.deleteBook()
+      }, secondaryButton: .cancel())
+    }
+    .navigationBarItems(trailing: Button(action: {
+      self.showingDeleteAlert = true
+    }) {
+      Image(systemName: "trash")
+    })
+  }
+
+  func formattedDate(for book: Book) -> String {
+    let formatter = DateFormatter()
+    formatter.dateStyle = .short
+    return "Date added: \(formatter.string(from: book.date ?? Date()))"
+  }
+
+  func deleteBook() {
+    moc.delete(book)
+
+    try? moc.save()
+    presentationMode.wrappedValue.dismiss()
+  }
+}
+
+struct DetailView_Previews: PreviewProvider {
+  static let moc = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
+
+  static var previews: some View {
+    let book = Book(context: moc)
+    book.title = "Test book"
+    book.author = "Test author"
+    book.genre = "Fantasy"
+    book.rating = 4
+    book.review = "This was a great book; I really enjoyed it."
+
+    return NavigationView {
+      DetailView(book: book)
+    }
+  }
+}

Snapshots/SwiftUI/Bookworm/EmojiRatingView.swift

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+//
+//  EmojiRatingView.swift
+//  Bookworm
+//
+//  Created by Nick Lockwood on 30/06/2020.
+//  Copyright © 2020 Nick Lockwood. All rights reserved.
+//
+
+import SwiftUI
+
+struct EmojiRatingView: View {
+  let rating: Int16
+
+  var body: some View {
+    switch rating {
+    case 1:
+      return Text("😴")
+    case 2:
+      return Text("☹️")
+    case 3:
+      return Text("😐")
+    case 4:
+      return Text("😄")
+    default:
+      return Text("🤩")
+    }
+  }
+}
+
+struct EmojiRatingView_Previews: PreviewProvider {
+  static var previews: some View {
+    EmojiRatingView(rating: 3)
+  }
+}

Snapshots/SwiftUI/Bookworm/RatingView.swift

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+//
+//  RatingView.swift
+//  Bookworm
+//
+//  Created by Nick Lockwood on 30/06/2020.
+//  Copyright © 2020 Nick Lockwood. All rights reserved.
+//
+
+import SwiftUI
+
+struct RatingView: View {
+  @Binding var rating: Int
+
+  var label = ""
+
+  var maximumRating = 5
+
+  var offImage: Image?
+  var onImage = Image(systemName: "star.fill")
+
+  var offColor = Color.gray
+  var onColor = Color.yellow
+
+  var body: some View {
+    HStack {
+      if label.isEmpty == false {
+        Text(label)
+      }
+
+      ForEach(1 ..< maximumRating + 1) { number in
+        self.image(for: number)
+          .foregroundColor(number > self.rating ? self.offColor : self.onColor)
+          .onTapGesture {
+            self.rating = number
+          }
+      }
+    }
+  }
+
+  func image(for number: Int) -> Image {
+    number > rating ? offImage ?? onImage : onImage
+  }
+}
+
+struct RatingView_Previews: PreviewProvider {
+  static var previews: some View {
+    RatingView(rating: .constant(4))
+  }
+}

Snapshots/SwiftUI/CupcakeCorner/AddressView.swift

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+//
+//  AddressView.swift
+//  CupcakeCorner
+//
+//  Created by Nick Lockwood on 28/06/2020.
+//  Copyright © 2020 Nick Lockwood. All rights reserved.
+//
+
+import SwiftUI
+
+struct AddressView: View {
+  @ObservedObject var order = Order()
+
+  var body: some View {
+    Form {
+      Section {
+        TextField("Name", text: $order.data.name)
+        TextField("Street Address", text: $order.data.streetAddress)
+        TextField("City", text: $order.data.city)
+        TextField("Zip", text: $order.data.zip)
+      }
+
+      Section {
+        NavigationLink(destination: CheckoutView(order: order)) {
+          Text("Check out")
+        }
+      }.disabled(!order.data.hasValidAddress)
+    }
+    .navigationBarTitle("Delivery details", displayMode: .inline)
+  }
+}
+
+struct AddressView_Previews: PreviewProvider {
+  static var previews: some View {
+    AddressView(order: Order())
+  }
+}