Add AnimationTests

Author: Kyle-Ye

Example/OpenSwiftUIUITests/Graphic/Color/ColorAnimationExampleUITests.swift

@@ -57,4 +57,26 @@ struct ColorUITests {
             testName: "hsb_\(name)"
         )
     }
+
+    @Test
+    func colorAnimation() {
+        struct ContentView: View {
+            @State private var showRed = false
+            var body: some View {
+                VStack {
+                    Color(platformColor: showRed ? .red : .blue)
+                        .frame(width: showRed ? 50 : 100, height: showRed ? 50 : 100)
+                }
+                .animation(.easeInOut(duration: 1), value: showRed)
+                .onAppear {
+                    showRed.toggle()
+                }
+            }
+        }
+        let model = AnimationTestModel(duration: 1, count: 10)
+        openSwiftUIAssertAnimationSnapshot(
+            of: ContentView(),
+            model: model,
+        )
+    }
 }

Example/OpenSwiftUIUITests/Graphic/Color/ColorUITests.swift

@@ -0,0 +1,40 @@
+//
+//  AnimationDebugController.swift
+//  OpenSwiftUIUITests
+
+import Foundation
+
+struct AnimationTestModel: Hashable {
+    var intervals: [Double]
+
+    init(intervals: [Double]) {
+        self.intervals = intervals
+    }
+
+    init(times: [Double]) {
+        intervals = zip(times.dropFirst(), times).map { $0 - $1 }
+    }
+
+    init(duration: Double, count: Int) {
+        intervals = Array(repeating: duration / Double(count), count: count)
+    }
+}
+
+final class AnimationDebugController<V>: UIHostingController<V> where V: View {
+    init(_ view: V) {
+        super.init(rootView: view)
+    }
+    
+    @MainActor
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    func advance(interval: Double) {
+        (view as! _UIHostingView<V>)._renderForTest(interval: interval)
+    }
+
+    func advanceAsync(interval: Double) -> Bool {
+        (view as! _UIHostingView<V>)._renderAsyncForTest(interval: interval)
+    }
+}

Example/OpenSwiftUIUITests/UITests/AnimationDebugController.swift

@@ -155,3 +155,38 @@ private func openSwiftUIAssertSnapshot<Value, Format>(
         )
     )
 }
+
+// MARK: - Animation
+
+func openSwiftUIAssertAnimationSnapshot<V: View>(
+    of value: @autoclosure () -> V,
+    model: AnimationTestModel,
+    perceptualPrecision: Float = 1,
+    size: CGSize = defaultSize,
+    record recording: Bool? = shouldRecord,
+    timeout: TimeInterval = 5,
+    fileID: StaticString = #fileID,
+    file filePath: StaticString = #filePath,
+    testName: String = #function,
+    line: UInt = #line,
+    column: UInt = #column
+) {
+    let vc = AnimationDebugController(value())
+    // Flush the neccessary onAppear etc. stuff
+    vc.advance(interval: .zero)
+    model.intervals.enumerated().forEach { (index, interval) in
+        vc.advance(interval: interval)
+        openSwiftUIAssertSnapshot(
+            of: vc,
+            as: .image(perceptualPrecision: perceptualPrecision, size: size),
+            named: "\(index + 1)_\(model.intervals.count).\(Int(size.width))x\(Int(size.height))",
+            record: recording,
+            timeout: timeout,
+            fileID: fileID,
+            file: filePath,
+            testName: testName,
+            line: line,
+            column: column
+        )
+    }
+}