test: swiftui preferredcontentsize

Author: watt

WorkflowSwiftUI/Tests/PreferredContentSizeTests.swift

@@ -0,0 +1,123 @@
+#if canImport(UIKit)
+
+import SwiftUI
+import Workflow
+import WorkflowSwiftUI
+import XCTest
+
+final class PreferredContentSizeTests: XCTestCase {
+    func test_preferredContentSize() {
+        let maxWidth: CGFloat = 50
+        let maxHeight: CGFloat = 50
+
+        func assertPreferredContentSize(in axes: Axis.Set) {
+            let screen = TestScreen(model: .constant(state: State(axes: axes)))
+            let viewController = screen.buildViewController(in: .empty)
+            viewController.view.frame = CGRect(x: 0, y: 0, width: maxWidth, height: maxHeight)
+            viewController.view.layoutIfNeeded()
+
+            func assertContentSize(
+                _ contentSize: CGSize,
+                expected: CGSize? = nil,
+                file: StaticString = #filePath,
+                line: UInt = #line
+            ) {
+                let state = State(width: contentSize.width, height: contentSize.height, axes: axes)
+                let screen = TestScreen(model: .constant(state: state))
+                screen.update(viewController: viewController, with: .empty)
+
+                viewController.view.layoutIfNeeded()
+                let pcs = viewController.preferredContentSize
+
+                XCTAssertEqual(
+                    pcs,
+                    expected ?? contentSize,
+                    "Axes: \(axes.testDescription)",
+                    file: file,
+                    line: line
+                )
+            }
+
+            assertContentSize(CGSize(width: 20, height: 20))
+            assertContentSize(CGSize(width: 40, height: 20))
+            assertContentSize(CGSize(width: 20, height: 40))
+            assertContentSize(
+                CGSize(width: 100, height: 100),
+                expected: CGSize(
+                    width: axes.contains(.horizontal) ? maxWidth : 100,
+                    height: axes.contains(.vertical) ? maxHeight : 100
+                )
+            )
+        }
+
+        assertPreferredContentSize(in: [])
+        assertPreferredContentSize(in: .horizontal)
+        assertPreferredContentSize(in: .vertical)
+        assertPreferredContentSize(in: [.horizontal, .vertical])
+    }
+}
+
+extension Axis.Set {
+    var testDescription: String {
+        switch self {
+        case .horizontal: "[horizontal]"
+        case .vertical: "[vertical]"
+        case [.horizontal, .vertical]: "[horizontal, vertical]"
+        default: "[]"
+        }
+    }
+}
+
+@ObservableState
+private struct State {
+    var width: CGFloat = 0
+    var height: CGFloat = 0
+    var axes: Axis.Set = []
+}
+
+private struct TestWorkflow: Workflow {
+    typealias Rendering = StateAccessor<State>
+
+    func makeInitialState() -> State {
+        State()
+    }
+
+    func render(state: State, context: RenderContext<TestWorkflow>) -> Rendering {
+        context.makeStateAccessor(state: state)
+    }
+}
+
+private struct TestScreen: ObservableScreen {
+    typealias Model = StateAccessor<State>
+
+    var model: Model
+
+    var sizingOptions: SwiftUIScreenSizingOptions = .preferredContentSize
+
+    @ViewBuilder
+    static func makeView(store: Store<Model>) -> some View {
+        TestView(store: store)
+    }
+}
+
+private struct TestView: View {
+    var store: Store<StateAccessor<State>>
+
+    var body: some View {
+        WithPerceptionTracking {
+            if store.axes.isEmpty {
+                box
+            } else {
+                ScrollView(store.axes) {
+                    box
+                }
+            }
+        }
+    }
+
+    var box: some View {
+        Color.red.frame(width: store.width, height: store.height)
+    }
+}
+
+#endif