### Snapshot Variants Example

Source: https://github.com/getsentry/snapshotpreviews/blob/main/README.md

This example demonstrates how to use PreviewVariants to render a view under multiple conditions like dark mode, RTL, and large text. Each previewVariant becomes a separate snapshot.

```swift
struct MyView_Previews: PreviewProvider {
  static var previews: some View {
    PreviewVariants(layout: .sizeThatFits) {
      MyView(mode: .loaded)
        .previewVariant(named: "My View - Loaded")

      MyView(mode: .loading)
        .previewVariant(named: "My View - Loading")

      MyView(mode: .error)
        .previewVariant(named: "My View - Error")
    }
  }
}
```

--------------------------------

### Basic SnapshotTest Class Setup

Source: https://github.com/getsentry/snapshotpreviews/blob/main/README.md

Create a test class inheriting from SnapshotTest to generate snapshots from Xcode previews. No test functions are needed as they are generated at runtime.

```swift
import SnapshottingTests

class DemoAppPreviewTest: SnapshotTest {

  // Optional: return preview type names like "MyApp.MyView_Previews" to render only a subset.
  override class func snapshotPreviews() -> [String]? {
    return nil
  }

  // Optional: exclude specific previews from rendering.
  override class func excludedSnapshotPreviews() -> [String]? {
    return nil
  }
}
```

--------------------------------

### Migrated Snapshot Test Example

Source: https://github.com/getsentry/snapshotpreviews/blob/main/Examples/UnitTestMigration/README.md

This Swift code demonstrates a migrated unit test. It inherits from SnapshotTest and conforms to PreviewProvider, automatically converting snapshot assertions into SwiftUI previews. Ensure the SnapshotTest base class is added to your project.

```swift
import SwiftUI

// Add the conformance to `PreviewProvider` when extending `SnapshotTest`
// The `SnapshotTest` base class automatically handles turning calls to
// assertSnapshot into previews.
class ExampleSnapshotTest: SnapshotTest, PreviewProvider {

  func testContentViewSnapshot() {
    assertSnapshot(of: ContentView(), as: .image)
  }
}
```

--------------------------------

### Add SnapshotPreviews as a Swift Package Manager Dependency

Source: https://github.com/getsentry/snapshotpreviews/blob/main/README.md

To install SnapshotPreviews, add the repository URL to your Swift Package Manager dependencies.

```bash
https://github.com/EmergeTools/SnapshotPreviews
```

--------------------------------

### Run Xcode Tests from Command Line

Source: https://github.com/getsentry/snapshotpreviews/blob/main/Examples/MultiModuleDemo/README.md

Execute Xcode tests for the MultiModuleDemo scheme, specifying the output directory for snapshots and excluding specific test cases. This command is useful for automated testing and CI environments.

```bash
TEST_RUNNER_SNAPSHOTS_EXPORT_DIR=/tmp/snapshots xcodebuild test \
  -scheme MultiModuleDemo \
  -sdk iphonesimulator \
  -destination 'platform=iOS Simulator,name=iPhone 17 Pro Max' \
  -skip-testing:MultiModuleDemoTests/ModuleFilterAssertionTests \
  CODE_SIGNING_ALLOWED=NO \
  | xcpretty
```

--------------------------------

### Presenting the Preview Gallery in SwiftUI

Source: https://github.com/getsentry/snapshotpreviews/blob/main/README.md

Integrate the PreviewGallery into your SwiftUI app to create a browsable gallery of components. This is useful for internal builds.

```swift
import SwiftUI
import PreviewGallery

struct InternalSettingsView: View {
  var body: some View {
    NavigationStack {
      Form {
        Section("Previews") {
          NavigationLink("Open Gallery") { PreviewGallery() }
        }
      }
    }
    .navigationTitle("Internal Settings")
  }
}
```

--------------------------------

### Configure Snapshot Previews in Swift

Source: https://github.com/getsentry/snapshotpreviews/blob/main/README.md

Use snapshot modifiers to customize tags, additional context, and diff thresholds for individual previews. Ensure SnapshotPreferences is imported.

```swift
import SnapshotPreferences

#Preview("Map") {
  MapPreview()
    .snapshotTags(["screen": "map"])
    .snapshotAdditionalContext(["fixture": "city-route"])
    .snapshotDiffThreshold(0.05)
}
```

--------------------------------

### GitHub Actions Step for Snapshot Tests

Source: https://github.com/getsentry/snapshotpreviews/blob/main/README.md

A complete GitHub Actions workflow step to run snapshot tests and upload the results to Sentry. It configures the export directory and uses secrets for the auth token.

```yaml
- name: Run snapshot tests
  env:
    TEST_RUNNER_SNAPSHOTS_EXPORT_DIR: ${{ github.workspace }}/snapshot-images
  run: |
    xcodebuild test \
      -scheme MyApp \
      -sdk iphonesimulator \
      -destination 'platform=iOS Simulator,name=iPhone 15 Pro'

- name: Upload snapshots to Sentry
  env:
    SENTRY_AUTH_TOKEN: ${{ secrets.SENTRY_AUTH_TOKEN }}
  run: |
    sentry-cli build snapshots "$GITHUB_WORKSPACE/snapshot-images" \
      --app-id com.example.MyApp \
      --project my-ios-project
```

--------------------------------

### Filter Snapshots by Module

Source: https://github.com/getsentry/snapshotpreviews/blob/main/README.md

Configure which modules to include or exclude from snapshot generation. This is useful for large projects with multiple frameworks.

```swift
// Only snapshot previews from these modules
override class func snapshotPreviewModules() -> [String]? { ["MyFeatureModule"] }

// Skip previews from these modules
override class func excludedSnapshotPreviewModules() -> [String]? { ["LegacyModule"] }
```

--------------------------------

### Upload Snapshots with sentry-cli

Source: https://github.com/getsentry/snapshotpreviews/blob/main/README.md

Upload exported snapshot images to Sentry using sentry-cli. Provide the path to the exported images, an auth token, app ID, and project name.

```bash
sentry-cli build snapshots "$PWD/snapshot-images" \
  --auth-token "$SENTRY_AUTH_TOKEN" \
  --app-id com.example.MyApp \
  --project my-ios-project
```

--------------------------------

### Detect Running Previews

Source: https://github.com/getsentry/snapshotpreviews/blob/main/README.md

Use this extension to check if the current environment is running Xcode Previews. This helps disable preview-unfriendly behavior like logging or network calls.

```swift
extension ProcessInfo {
  var isRunningPreviews: Bool {
    environment["SNAPSHOTS_RUNNING_FOR_PREVIEWS"] == "1"
  }
}
```

--------------------------------

### SwiftUI View Preview Source Interface

Source: https://github.com/getsentry/snapshotpreviews/blob/main/PreviewsSupport/README.md

Add this struct definition to the end of SwiftUI's .swiftinterface files to enable ViewPreviewSource extraction.

```swift
@available(iOS 17.0, macOS 14.0, *) public struct ViewPreviewSource {
  public var makeView: @_Concurrency.MainActor () -> any SwiftUI.View
}
```

--------------------------------

### UIKit UIView Preview Source Interface

Source: https://github.com/getsentry/snapshotpreviews/blob/main/PreviewsSupport/README.md

Add this struct definition to the end of UIKit's .swiftinterface files for UIView preview extraction.

```swift
@available(iOS 17.0, macOS 14.0, *) public struct UIViewPreviewSource {
  public var makeView: @_Concurrency.MainActor () -> UIKit.UIView
}
```

--------------------------------

### Set Unique Display Names for Previews

Source: https://github.com/getsentry/snapshotpreviews/blob/main/README.md

Ensure each preview has a unique display name for clarity in test results and exported files. This applies to both PreviewProvider and #Preview macro usage.

```swift
struct MyView_Previews: PreviewProvider {
  static var previews: some View {
    MyView().previewDisplayName("My Display Name")
  }
}

#Preview("My Display Name") {
  MyView()
}
```

--------------------------------

### UIKit UIViewController Preview Source Interface

Source: https://github.com/getsentry/snapshotpreviews/blob/main/PreviewsSupport/README.md

Add this struct definition to the end of UIKit's .swiftinterface files for UIViewController preview extraction.

```swift
@available(iOS 17.0, macOS 14.0, *) public struct UIViewControllerPreviewSource {
  public var makeViewController: @_Concurrency.MainActor () -> UIKit.UIViewController
}
```

--------------------------------

### Export Snapshots with xcodebuild

Source: https://github.com/getsentry/snapshotpreviews/blob/main/README.md

Set the TEST_RUNNER_SNAPSHOTS_EXPORT_DIR environment variable to specify the output directory for snapshot images when running xcodebuild tests. This directs images to a specified directory instead of the .xcresult bundle.

```bash
TEST_RUNNER_SNAPSHOTS_EXPORT_DIR="$PWD/snapshot-images" \
xcodebuild test \
  -scheme MyApp \
  -sdk iphonesimulator \
  -destination 'platform=iOS Simulator,name=iPhone 15 Pro'
```

--------------------------------

### Implementing Accessibility Audits with XCTest

Source: https://github.com/getsentry/snapshotpreviews/blob/main/README.md

Inherit from AccessibilityPreviewTest to run Xcode accessibility audits on your previews as part of a UI test. Override auditType and handle issues as needed.

```swift
import SnapshottingTests
import Snapshotting

class DemoAppAccessibilityPreviewTest: AccessibilityPreviewTest {

  override func auditType() -> XCUIAccessibilityAuditType {
    return .all
  }

  override func handle(issue: XCUIAccessibilityAuditIssue) -> Bool {
    return false
  }
}
```

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