New preview tests (#149)

DemoApp/Demo Watch AppTests/DemoWatchPreviewTest.swift

@@ -0,0 +1,13 @@
+//
+//  DemoWatchPreviewTest.swift
+//  Demo Watch AppTests
+//
+//  Created by Noah Martin on 8/10/24.
+//
+
+import XCTest
+import SnapshottingTests
+
+final class DemoWatchPreviewTest: PreviewLayoutTest {
+
+}

DemoApp/Demo Watch AppTests/DemoWatchSnapshotTest.swift

@@ -0,0 +1,13 @@
+//
+//  DemoWatchSnapshotTest.swift
+//  Demo Watch AppTests
+//
+//  Created by Noah Martin on 8/10/24.
+//
+
+import Foundation
+import SnapshottingTests
+
+final class DemoWatchSnapshotTest: SnapshotTest {
+
+}

DemoApp/DemoAppTests/DemoAppPreviewTest.swift

@@ -0,0 +1,19 @@
+//
+//  DemoAppPreviewTest.swift
+//  DemoAppTests
+//
+//  Created by Noah Martin on 8/9/24.
+//
+
+import XCTest
+import SnapshottingTests
+
+final class DemoAppPreviewTest: PreviewLayoutTest {
+  override func snapshotPreviews() -> [String]? {
+    return nil
+  }
+
+  override func excludedSnapshotPreviews() -> [String]? {
+    return nil
+  }
+}

DemoApp/DemoAppTests/DemoAppSnapshotTest.swift

@@ -0,0 +1,19 @@
+//
+//  DemoAppSnapshotTest.swift
+//  DemoAppTests
+//
+//  Created by Noah Martin on 8/10/24.
+//
+
+import Foundation
+import SnapshottingTests
+
+class DemoAppSnapshotTest: SnapshotTest {
+  override func snapshotPreviews() -> [String]? {
+    return nil
+  }
+
+  override func excludedSnapshotPreviews() -> [String]? {
+    return nil
+  }
+}

DemoApp/DemoAppUITests/MyPreviewTest.swift → DemoApp/DemoAppUITests/DemoAppAccessibilityPreviewTest.swift

@@ -1,5 +1,5 @@
 //
-//  MultipleTests.swift
+//  DemoAppAccessibilityPreviewTest.swift
 //  DemoAppUITests
 //
 //  Created by Noah Martin on 7/14/23.
@@ -9,7 +9,8 @@ import Foundation
 import XCTest
 import SnapshottingTests
 
-class MyPreviewTest: PreviewTest {
+@available(iOS 17.0, macOS 14.0, tvOS 17.0, watchOS 10.0, *)
+class DemoAppAccessibilityPreviewTest: AccessibilityPreviewTest {
 
   override func snapshotPreviews() -> [String]? {
     return nil
@@ -19,10 +20,6 @@ class MyPreviewTest: PreviewTest {
     return nil
   }
 
-  override var enableAccessibilityAudit: Bool {
-    true
-  }
-
   @available(iOS 17.0, *)
   override func auditType() -> XCUIAccessibilityAuditType {
     return .all

DemoApp/DemoWatchTests/Demo.swift → DemoApp/DemoWatchTests/DemoWatchAccessibilityPreviewTest.swift

@@ -1,5 +1,5 @@
 //
-//  Demo.swift
+//  DemoWatchAccessibilityPreviewTest.swift
 //  Demo
 //
 //  Created by Noah Martin on 7/5/24.
@@ -9,7 +9,7 @@ import Snapshotting
 import SnapshottingTests
 import XCTest
 
-final class Demo: PreviewTest {
+final class DemoWatchAccessibilityPreviewTest: AccessibilityPreviewTest {
 
   override func getApp() -> XCUIApplication {
     return XCUIApplication()

Sources/SnapshotPreviewsCore/SnapshotPreviewsCore.swift

@@ -177,8 +177,8 @@ public enum FindPreviews {
 
   @MainActor
   public static func findPreviews(included: [String]?, excluded: [String]?) -> [PreviewType] {
-    var previewsSet = included.map { Set($0) }
-    var excludedPreviewsSet = excluded.map { Set($0) }
+    let previewsSet = included.map { Set($0) }
+    let excludedPreviewsSet = excluded.map { Set($0) }
 
     let previewTypes = findPreviews { name, proto in
       guard #available(iOS 16.0, macOS 13.0, tvOS 16.0, *) else { return true }

Sources/SnapshottingTests/PreviewTest.swift → Sources/SnapshottingTests/AccessibilityPreviewTest.swift

@@ -1,6 +1,6 @@
 //
-//  PreviewTest.swift
-//  
+//  AccessibilityPreviewTest.swift
+//
 //
 //  Created by Noah Martin on 8/9/24.
 //
@@ -9,7 +9,9 @@ import Foundation
 import SnapshottingTestsObjc
 import MachO
 
-open class PreviewTest: EMGPreviewBaseTest {
+// This is an XCUITest that uses XCUIApplication.performAccessibilityAudit to test previews
+@available(iOS 17.0, macOS 14.0, tvOS 17.0, watchOS 10.0, *)
+open class AccessibilityPreviewTest: EMGPreviewBaseTest {
 
   open func getApp() -> XCUIApplication {
     XCUIApplication()
@@ -26,10 +28,6 @@ open class PreviewTest: EMGPreviewBaseTest {
     nil
   }
 
-  open var enableAccessibilityAudit: Bool {
-    true
-  }
-
   @available(iOS 17.0, macOS 14.0, tvOS 17.0, watchOS 10.0, *)
   open func auditType() -> XCUIAccessibilityAuditType { .all }
 
@@ -159,13 +157,9 @@ open class PreviewTest: EMGPreviewBaseTest {
       XCTFail("Failed to parse JSON: \(error)")
     }
 
-    if #available(iOS 17.0, macOS 14.0, tvOS 17.0, watchOS 10.0, *) {
-      if enableAccessibilityAudit {
-        let app = getApp()
-        try? app.performAccessibilityAudit(for: auditType()) { [weak self] issue in
-          return self?.handle(issue: issue) ?? false
-        }
-      }
+    let app = getApp()
+    try? app.performAccessibilityAudit(for: auditType()) { [weak self] issue in
+      return self?.handle(issue: issue) ?? false
     }
   }
 }

Sources/SnapshottingTests/EMGPreviewBaseTest+PreviewFilters.swift

@@ -0,0 +1,28 @@
+//
+//  EMGPreviewBaseTest+PreviewFilters.swift
+//
+//
+//  Created by Noah Martin on 8/9/24.
+//
+
+import Foundation
+import SnapshotPreviewsCore
+import SnapshottingTestsObjc
+
+extension PreviewFilters where Self: EMGPreviewBaseTest {
+  @MainActor
+  static func matchingPreviewTypes() -> [PreviewType] {
+    let instance = self.create()
+    return FindPreviews.findPreviews(included: instance.snapshotPreviews(), excluded: instance.excludedSnapshotPreviews())
+  }
+}
+
+extension EMGDiscoveredPreview {
+  static func from(previewType: PreviewType) -> EMGDiscoveredPreview {
+    let d = EMGDiscoveredPreview()
+    d.typeName = previewType.typeName
+    d.displayName = previewType.displayName
+    d.numberOfPreviews = NSNumber(value: previewType.previews.count)
+    return d
+  }
+}

Sources/SnapshottingTests/PreviewFilters.swift

@@ -0,0 +1,17 @@
+//
+//  PreviewFilters.swift
+//
+//
+//  Created by Noah Martin on 8/9/24.
+//
+
+import Foundation
+
+public protocol PreviewFilters {
+  // Override to return a list of previews that should be snapshotted.
+  // The default is null, which snapshots all previews.
+  // Elements should be the type name of the preview, like "MyModule.MyView_Previews"
+  func snapshotPreviews() -> [String]?
+
+  func excludedSnapshotPreviews() -> [String]?
+}

Sources/SnapshottingTests/PreviewLayoutTest.swift

@@ -0,0 +1,54 @@
+//
+//  PreviewLayoutTest.swift
+//  
+//
+//  Created by Noah Martin on 8/9/24.
+//
+
+import Foundation
+import SnapshotPreviewsCore
+import SnapshottingTestsObjc
+import SwiftUI
+
+// Test Xcode previews by forcing a layout pass of each one
+open class PreviewLayoutTest: EMGPreviewBaseTest, PreviewFilters {
+
+  open func snapshotPreviews() -> [String]?  {
+    nil
+  }
+
+  open func excludedSnapshotPreviews() -> [String]? {
+    nil
+  }
+
+  static private var previews: [PreviewType] = []
+
+  @MainActor
+  open override class func discoverPreviews() -> [EMGDiscoveredPreview] {
+    previews = matchingPreviewTypes()
+    return previews.map { EMGDiscoveredPreview.from(previewType: $0) }
+  }
+
+  @MainActor
+  open override func test(_ preview: EMGPreview) {
+    let previewType = Self.previews.first { $0.typeName == preview.preview.typeName }
+    guard let preview = previewType?.previews[preview.index.intValue] else {
+      XCTFail("Preview not found")
+      return
+    }
+
+    #if canImport(UIKit) && !os(watchOS)
+    let hostingVC = UIHostingController(rootView: AnyView(preview.view()))
+    #if os(visionOS) || os(watchOS)
+    hostingVC.view.sizeThatFits(CGSize(width: 100, height: CGFloat.greatestFiniteMagnitude))
+    #else
+    hostingVC.view.sizeThatFits(UIScreen.main.bounds.size)
+    #endif
+    #elseif canImport(AppKit)
+    let hostingVC = NSHostingController(rootView: AnyView(preview.view()))
+    _ = hostingVC.sizeThatFits(in: NSScreen.main!.frame.size)
+    #else
+    _ = ImageRenderer(content: AnyView(preview.view())).uiImage
+    #endif
+  }
+}

Sources/SnapshottingTests/SnapshotTest.swift

@@ -0,0 +1,72 @@
+//
+//  SnapshotTest.swift
+//
+//
+//  Created by Noah Martin on 8/9/24.
+//
+
+import Foundation
+import SnapshotPreviewsCore
+import SnapshottingTestsObjc
+
+// Generate snapshots of Xcode previews
+open class SnapshotTest: EMGPreviewBaseTest, PreviewFilters {
+
+  open func snapshotPreviews() -> [String]?  {
+    nil
+  }
+
+  open func excludedSnapshotPreviews() -> [String]? {
+    nil
+  }
+
+  private static func getRenderingStrategy() -> RenderingStrategy {
+    #if canImport(UIKit) && !os(watchOS) && !os(visionOS) && !os(tvOS)
+      return UIKitRenderingStrategy()
+    #else
+    if #available(iOS 16.0, macOS 13.0, tvOS 16.0, watchOS 9.0, visionOS 1.0, *) {
+      SwiftUIRenderingStrategy()
+    } else {
+      preconditionFailure("Cannot snapshot on this device/os")
+    }
+    #endif
+  }
+  private let renderingStrategy = getRenderingStrategy()
+
+  static private var previews: [SnapshotPreviewsCore.PreviewType] = []
+
+  @MainActor
+  open override class func discoverPreviews() -> [EMGDiscoveredPreview] {
+    previews = matchingPreviewTypes()
+    return previews.map { EMGDiscoveredPreview.from(previewType: $0) }
+  }
+
+  @MainActor
+  open override func test(_ preview: EMGPreview) {
+    let previewType = Self.previews.first { $0.typeName == preview.preview.typeName }
+    guard let preview = previewType?.previews[preview.index.intValue] else {
+      XCTFail("Preview not found")
+      return
+    }
+
+    var result: SnapshotResult? = nil
+    let expectation = XCTestExpectation()
+    renderingStrategy.render(preview: preview) { snapshotResult in
+      result = snapshotResult
+      expectation.fulfill()
+    }
+    wait(for: [expectation], timeout: 10)
+    guard let result else {
+      XCTFail("Did not render")
+      return
+    }
+    do {
+      let attachment = try XCTAttachment(image: result.image.get())
+      attachment.name = preview.displayName
+      attachment.lifetime = .keepAlways
+      add(attachment)
+    } catch {
+      XCTFail("Error \(error)")
+    }
+  }
+}