Initial Commit

.gitignore

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+.DS_Store
+/.build
+/Packages
+/*.xcodeproj
+xcuserdata/
+DerivedData/
+.swiftpm/config/registries.json
+.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata
+.netrc
+Package.resolved

Examples/PreviewSnapshotsTestApp.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist

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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>

Examples/PreviewSnapshotsTestApp/Assets.xcassets/AccentColor.colorset/Contents.json

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+{
+  "colors" : [
+    {
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Examples/PreviewSnapshotsTestApp/Assets.xcassets/AppIcon.appiconset/Contents.json

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+{
+  "images" : [
+    {
+      "idiom" : "universal",
+      "platform" : "ios",
+      "size" : "1024x1024"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Examples/PreviewSnapshotsTestApp/Assets.xcassets/Contents.json

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+{
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Examples/PreviewSnapshotsTestApp/ObservableObjectView.swift

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+// Copyright 2022 DoorDash, Inc.
+//
+// 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 PreviewSnapshots
+import SwiftUI
+
+final class ObservableObjectViewModel: ObservableObject {
+    @Published var input = ""
+    @Published var errorMessage: String?
+
+    func validate() {
+        if input.count < 5 {
+            errorMessage = "Message Too Short"
+        } else {
+            errorMessage = nil
+        }
+    }
+}
+
+struct ObservableObjectView: View {
+    @ObservedObject var viewModel: ObservableObjectViewModel
+
+    var body: some View {
+        VStack(spacing: 8) {
+            TextField("Input", text: $viewModel.input)
+
+            if let errorMessage = viewModel.errorMessage {
+                Text(errorMessage)
+                    .font(.caption)
+                    .foregroundColor(.red)
+            }
+
+            Button("Submit") {
+                viewModel.validate()
+            }
+        }
+        .padding(8)
+    }
+}
+
+struct ObservableObjectView_Previews: PreviewProvider {
+    static var previews: some View {
+        snapshots.previews.previewLayout(.sizeThatFits)
+    }
+
+    static var snapshots: PreviewSnapshots<ObservableObjectViewModel> {
+        let empty = ObservableObjectViewModel()
+
+        let tooShort = ObservableObjectViewModel()
+        tooShort.input = "Hi"
+        tooShort.validate()
+
+        let valid = ObservableObjectViewModel()
+        valid.input = "Hello World"
+        valid.validate()
+
+        return PreviewSnapshots(
+            configurations: [
+                .init(name: "Empty", state: empty),
+                .init(name: "Too Short", state: tooShort),
+                .init(name: "Valid", state: valid),
+            ],
+            configure: {
+                ObservableObjectView(viewModel: $0)
+            }
+        )
+    }
+}

Examples/PreviewSnapshotsTestApp/PreviewSnapshotsTestApp.swift

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+// Copyright 2022 DoorDash, Inc.
+//
+// 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 SwiftUI
+
+@main
+struct PreviewSnapshotsTestApp: App {
+    var body: some Scene {
+        WindowGroup {
+            NavigationView {
+                List {
+                    NavigationLink("Simple View") {
+                        SimpleView(message: "Hello World!")
+                    }
+
+                    NavigationLink("PreviewState View") {
+                        PreviewStateView(title: "Hello", subtitle: "Word", message: "Hello World")
+                    }
+
+                    NavigationLink("ObservableObject View") {
+                        ObservableObjectView(viewModel: .init())
+                    }
+                }
+                .navigationTitle("Test Views")
+            }
+        }
+    }
+}

Examples/PreviewSnapshotsTestApp/PreviewStateView.swift

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+// Copyright 2022 DoorDash, Inc.
+//
+// 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 PreviewSnapshots
+import SwiftUI
+
+struct PreviewStateView: View {
+    let title: String
+    let subtitle: String
+    let message: String
+
+    var body: some View {
+        VStack(spacing: 24) {
+            VStack(spacing: 8) {
+                Text(title)
+                    .font(.title)
+
+                Text(subtitle)
+                    .font(.subheadline)
+            }
+
+            Text(message)
+                .font(.body)
+        }
+        .multilineTextAlignment(.center)
+        .padding(8)
+    }
+}
+
+struct PreviewStateView_Previews: PreviewProvider {
+    static var previews: some View {
+        snapshots.previews.previewLayout(.sizeThatFits)
+    }
+
+    static var snapshots: PreviewSnapshots<PreviewState> {
+        PreviewSnapshots(
+            states: [
+                .init(name: "Short", title: "Hello", subtitle: "PreviewSnapshots", message: "This is a test"),
+                .init(
+                    name: "Long",
+                    title: "Hello PreviewSnapshots",
+                    subtitle: "Welcome to PreviewSnapshots",
+                    message: "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua."
+                )
+            ],
+            configure: {
+                PreviewStateView(title: $0.title, subtitle: $0.subtitle, message: $0.message)
+            }
+        )
+    }
+
+    struct PreviewState: NamedPreviewState {
+        let name: String
+        let title: String
+        let subtitle: String
+        let message: String
+    }
+}

Examples/PreviewSnapshotsTestApp/SimpleView.swift

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+// Copyright 2022 DoorDash, Inc.
+//
+// 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 PreviewSnapshots
+import SwiftUI
+
+struct SimpleView: View {
+    let message: String
+
+    var body: some View {
+        VStack(spacing: 8) {
+            Image(systemName: "globe")
+                .imageScale(.large)
+                .foregroundColor(.accentColor)
+
+            Text(message)
+        }
+        .padding(8)
+    }
+}
+
+struct SimpleView_Previews: PreviewProvider {
+    static var previews: some View {
+        snapshots.previews.previewLayout(.sizeThatFits)
+    }
+
+    static var snapshots: PreviewSnapshots<String> {
+        PreviewSnapshots(
+            configurations: [
+                .init(name: "Short Message", state: "Hello World"),
+                .init(name: "Long Message", state: "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua."),
+            ],
+            configure: {
+                SimpleView(message: $0)
+            }
+        )
+    }
+}

Examples/PreviewSnapshotsTestAppTests/PreviewSnapshotsTestAppTests.swift

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+// Copyright 2022 DoorDash, Inc.
+//
+// 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 PreviewSnapshotsTesting
+import SnapshotTesting
+import SwiftUI
+import XCTest
+
+@testable import PreviewSnapshotsTestApp
+
+final class PreviewSnapshotsTestAppTests: XCTestCase {
+    func test_simpleViewSnapshots() {
+        SimpleView_Previews.snapshots.assertSnapshots(as: .testStrategy())
+    }
+
+    func test_previewStateViewSnapshots() {
+        PreviewStateView_Previews.snapshots.assertSnapshots(as: .testStrategy())
+    }
+
+    func test_observableObjectSnapshots() {
+        ObservableObjectView_Previews.snapshots.assertSnapshots(as: .testStrategy())
+    }
+
+    func test_previewStateLightAndDark() {
+        PreviewStateView_Previews.snapshots
+            .assertSnapshots(as: [
+                "Light": .testStrategy(userInterfaceStyle: .light),
+                "Dark": .testStrategy(userInterfaceStyle: .dark),
+            ])
+    }
+}
+
+extension Snapshotting where Value: SwiftUI.View, Format == UIImage {
+    /// Shared image test strategy
+    static func testStrategy(userInterfaceStyle: UIUserInterfaceStyle = .light) -> Self {
+        let traits = UITraitCollection(traitsFrom: [
+            UITraitCollection(displayScale: 1),
+            UITraitCollection(userInterfaceStyle: userInterfaceStyle),
+        ])
+
+        return .image(
+            layout: .fixed(width: 400, height: 400),
+            traits: traits
+        )
+    }
+}