tillhainbach's fix for macOS

.github/workflows/ci.yml

@@ -23,6 +23,15 @@ jobs:
         run: sudo xcode-select -s /Applications/Xcode_${{ matrix.xcode }}.app
       - name: Run tests
         run: make test-swift
+        env:
+          SNAPSHOT_ARTIFACTS: "./.temp/artifacts"
+
+      - name: Archive failing snapshots
+        if: always()
+        uses: actions/upload-artifact@v2
+        with:
+          name: failing-snapshots
+          path: .temp/artifacts
 
   ubuntu:
     strategy:

Sources/SnapshotTesting/Snapshotting/CGPath.swift

@@ -150,6 +150,7 @@
 
   private let defaultNumberFormatter: NumberFormatter = {
     let numberFormatter = NumberFormatter()
+    numberFormatter.decimalSeparator = "."
     numberFormatter.minimumFractionDigits = 1
     numberFormatter.maximumFractionDigits = 3
     return numberFormatter

Sources/SnapshotTesting/Snapshotting/NSBezierPath.swift

@@ -103,10 +103,11 @@
     }
   }
 
-  private let defaultNumberFormatter: NumberFormatter = {
-    let numberFormatter = NumberFormatter()
-    numberFormatter.minimumFractionDigits = 1
-    numberFormatter.maximumFractionDigits = 3
-    return numberFormatter
-  }()
+private let defaultNumberFormatter: NumberFormatter = {
+  let numberFormatter = NumberFormatter()
+  numberFormatter.decimalSeparator = "."
+  numberFormatter.minimumFractionDigits = 1
+  numberFormatter.maximumFractionDigits = 3
+  return numberFormatter
+}()
 #endif

Sources/SnapshotTesting/Snapshotting/NSView.swift

@@ -8,28 +8,73 @@
       return .image()
     }
 
-    /// A snapshot strategy for comparing views based on pixel equality.
-    ///
-    /// > Note: Snapshots must be compared on the same OS as the device that originally took the
-    /// > reference to avoid discrepancies between images.
-    ///
-    /// - Parameters:
-    ///   - precision: The percentage of pixels that must match.
-    ///   - perceptualPrecision: The percentage a pixel must match the source pixel to be considered a
-    ///     match. 98-99% mimics
-    ///     [the precision](http://zschuessler.github.io/DeltaE/learn/#toc-defining-delta-e) of the
-    ///     human eye.
-    ///   - size: A view size override.
-    public static func image(
-      precision: Float = 1, perceptualPrecision: Float = 1, size: CGSize? = nil
-    ) -> Snapshotting {
-      return SimplySnapshotting.image(
-        precision: precision, perceptualPrecision: perceptualPrecision
-      ).asyncPullback { view in
-        let initialSize = view.frame.size
-        if let size = size { view.frame.size = size }
-        guard view.frame.width > 0, view.frame.height > 0 else {
-          fatalError("View not renderable to image at size \(view.frame.size)")
+  /// A snapshot strategy for comparing views based on pixel equality.
+  ///
+  /// >This function calls to `NSView.cacheDisplay()` which has side-effects that cannot be undone. Under some circumstances
+  /// >subviews will be added (e.g. for `NSButton`-views) and `NSView.needsLayout` will be set to `false`. Keep that in mind
+  /// >when asserting with `.image` and `.recursiveDescription` within the same test.
+  ///
+  /// - Parameters:
+  ///   - precision: The percentage of pixels that must match.
+  ///   - perceptualPrecision: The percentage a pixel must match the source pixel to be considered a match. [98-99% mimics the precision of the human eye.](http://zschuessler.github.io/DeltaE/learn/#toc-defining-delta-e)
+  ///   - size: A view size override.
+  ///   - appearance: The appearance to use when drawing the view. Pass `nil` to use the view’s existing appearance.
+  ///   - windowForDrawing: The choice of window to use when drawing the view. Pass `nil` to ignore.
+  public static func image(
+    precision: Float = 1,
+    perceptualPrecision: Float = 1,
+    size: CGSize? = nil,
+    appearance: NSAppearance? = NSAppearance(named: .aqua),
+    windowForDrawing: GenericWindow? = nil
+  ) -> Snapshotting {
+    return SimplySnapshotting.image(precision: precision, perceptualPrecision: perceptualPrecision).asyncPullback { view in
+      let initialFrame = view.frame
+      if let size = size { view.frame.size = size }
+      guard view.frame.width > 0, view.frame.height > 0 else {
+        fatalError("View not renderable to image at size \(view.frame.size)")
+      }
+
+      let initialAppearance = view.appearance
+      if let appearance = appearance {
+        view.appearance = appearance
+      }
+
+      if let windowForDrawing = windowForDrawing {
+        precondition(
+          view.window == nil,
+          """
+          If choosing to draw the view using a new window, the view must not already be attached to an existing window. \
+          (We wouldn’t be able to easily restore the view and all its associated constraints to the original window \
+          after moving it to the new window.)
+          """
+        )
+        windowForDrawing.contentView = NSView()
+        windowForDrawing.contentView?.addSubview(view)
+      }
+
+      return view.snapshot ?? Async { callback in
+        addImagesForRenderedViews(view).sequence().run { views in
+          let bitmapRep = view.bitmapImageRepForCachingDisplay(in: view.bounds)!
+          view.cacheDisplay(in: view.bounds, to: bitmapRep)
+          let image = NSImage(size: view.bounds.size)
+          image.addRepresentation(bitmapRep)
+          callback(image)
+          views.forEach { $0.removeFromSuperview() }
+          view.appearance = initialAppearance
+          view.frame = initialFrame
+
+          if windowForDrawing != nil {
+            view.removeFromSuperview()
+            view.layer = nil
+            view.subviews.forEach { subview in
+              subview.layer = nil
+            }
+            // This is to maintain compatibility with `recursiveDescription` because the current
+            // test snapshots expect `.needsLayout = false` and for some apple magic reason
+            // `view.needsLayout = false` does not do anything, but this does.
+            let bitmapRep = view.bitmapImageRepForCachingDisplay(in: view.bounds)!
+            view.cacheDisplay(in: view.bounds, to: bitmapRep)
+          }
         }
         return view.snapshot
           ?? Async { callback in
@@ -71,4 +116,36 @@
       }
     }
   }
+}
+
+/// A NSWindow which can be configured in a deterministic way.
+public final class GenericWindow: NSWindow {
+  public init(backingScaleFactor: CGFloat = 2.0, colorSpace: NSColorSpace? = nil) {
+    self._backingScaleFactor = backingScaleFactor
+    self._explicitlySpecifiedColorSpace = colorSpace
+
+    super.init(contentRect: NSRect.zero, styleMask: [], backing: .buffered, defer: true)
+  }
+
+  private let _explicitlySpecifiedColorSpace: NSColorSpace?
+  private var _systemSpecifiedColorspace: NSColorSpace?
+
+  private let _backingScaleFactor: CGFloat
+  public override var backingScaleFactor: CGFloat {
+    return _backingScaleFactor
+  }
+
+  public override var colorSpace: NSColorSpace? {
+    get {
+      _explicitlySpecifiedColorSpace ?? self._systemSpecifiedColorspace
+    }
+    set {
+      self._systemSpecifiedColorspace = newValue
+    }
+  }
+}
+
+extension GenericWindow {
+  static let ci = GenericWindow(backingScaleFactor: 1.0, colorSpace: .genericRGB)
+}
 #endif

Tests/SnapshotTestingTests/SnapshotTestingTests.swift

@@ -193,14 +193,14 @@ final class SnapshotTestingTests: XCTestCase {
 
   func testNSView() {
     #if os(macOS)
-      let button = NSButton()
-      button.bezelStyle = .rounded
-      button.title = "Push Me"
-      button.sizeToFit()
-      if !ProcessInfo.processInfo.environment.keys.contains("GITHUB_WORKFLOW") {
-        assertSnapshot(of: button, as: .image)
-        assertSnapshot(of: button, as: .recursiveDescription)
-      }
+    let button = NSButton()
+    button.bezelStyle = .rounded
+    button.title = "Push Me"
+    button.sizeToFit()
+    button.appearance = NSAppearance(named: .aqua)
+    if !ProcessInfo.processInfo.environment.keys.contains("GITHUB_WORKFLOW") {
+      assertSnapshot(matching: button, as: .image)
+    }
     #endif
   }
 
@@ -213,7 +213,6 @@ final class SnapshotTestingTests: XCTestCase {
       view.layer?.cornerRadius = 5
       if !ProcessInfo.processInfo.environment.keys.contains("GITHUB_WORKFLOW") {
         assertSnapshot(of: view, as: .image)
-        assertSnapshot(of: view, as: .recursiveDescription)
       }
     #endif
   }