Merge pull request #132 from liveviewnative/snapshot-testing

Snapshot Testing

Author: carson-katri

Package.swift

@@ -37,5 +37,9 @@ let package = Package(
         .testTarget(
             name: "LiveViewNativeTests",
             dependencies: ["LiveViewNative"]),
+        .testTarget(
+            name: "RenderingTests",
+            dependencies: ["LiveViewNative"]
+        )
     ]
 )

Tests/RenderingTests/TextTests.swift

@@ -0,0 +1,51 @@
+//
+//  TextTests.swift
+//  
+//
+//  Created by Carson Katri on 1/10/23.
+//
+
+import XCTest
+import SwiftUI
+@testable import LiveViewNative
+
+@MainActor
+final class TextTests: XCTestCase {
+    func testSimple() throws {
+        try assertMatch("<text>Hello, world!</text>") {
+            Text("Hello, world!")
+        }
+    }
+    func testStyles() throws {
+        for style in Font.TextStyle.allCases {
+            try assertMatch(#"<text font="\#(style)">Hello, world!</text>"#) {
+                Text("Hello, world!").font(.system(style, weight: .regular))
+            }
+        }
+    }
+    func testWeights() throws {
+        let allWeights: [String:Font.Weight] = [
+            "ultraLight": .ultraLight,
+            "thin": .thin,
+            "light": .light,
+            "regular": .regular,
+            "medium": .medium,
+            "semibold": .semibold,
+            "bold": .bold,
+            "heavy": .heavy,
+            "black": .black,
+        ]
+        for (name, weight) in allWeights {
+            try assertMatch(name: "weight-\(name)", #"<text font="body" font-weight="\#(name)">Hello, world!</text>"#) {
+                Text("Hello, world!").font(.system(.body, weight: weight))
+            }
+        }
+    }
+    func testColor() throws {
+        for color in [Color.primary, Color.red, Color.blue] {
+            try assertMatch(#"<text color="system-\#(color)">Hello, world!</text>"#) {
+                Text("Hello, world!").foregroundColor(color)
+            }
+        }
+    }
+}

Tests/RenderingTests/XCTestManifests.swift

@@ -0,0 +1,15 @@
+//
+//  XCTestManifests.swift
+//  
+//
+//  Created by Carson Katri on 1/10/23.
+//
+
+import XCTest
+
+#if !canImport(ObjectiveC)
+public func allTests() -> [XCTestCaseEntry] {
+    return [
+    ]
+}
+#endif

Tests/RenderingTests/assertMatch.swift

@@ -0,0 +1,49 @@
+//
+//  assertMatch.swift
+//  
+//
+//  Created by Carson Katri on 1/10/23.
+//
+
+import XCTest
+import SwiftUI
+import Foundation
+@testable import LiveViewNative
+import LiveViewNativeCore
+
+@MainActor
+func assertMatch(
+    _ markup: String,
+    _ file: String = #file,
+    _ line: Int = #line,
+    _ function: StaticString = #function,
+    @ViewBuilder _ view: () -> some View
+) throws {
+    try assertMatch(name: "\(URL(filePath: file).lastPathComponent)-\(line)-\(function)", markup, view)
+}
+
+@MainActor
+func assertMatch(
+    name: String,
+    _ markup: String,
+    @ViewBuilder _ view: () -> some View
+) throws {
+    let coordinator = LiveViewCoordinator(URL(string: "http://localhost")!)
+    let document = try LiveViewNativeCore.Document.parse(markup)
+    let viewTree = coordinator.builder.fromNodes(
+        document[document.root()].children(),
+        context: LiveContext(coordinator: coordinator, url: coordinator.currentURL)
+    ).environment(\.coordinatorEnvironment, CoordinatorEnvironment(coordinator, document: document))
+    let markupImage = ImageRenderer(content: viewTree).uiImage?.pngData()
+    let viewImage = ImageRenderer(content: view()).uiImage?.pngData()
+    
+    if markupImage == viewImage {
+        XCTAssert(true)
+    } else {
+        let markupURL = URL.temporaryDirectory.appendingPathComponent("\(name)_markup", conformingTo: .png)
+        let viewURL = URL.temporaryDirectory.appendingPathComponent("\(name)_view", conformingTo: .png)
+        try markupImage?.write(to: markupURL)
+        try viewImage?.write(to: viewURL)
+        XCTAssert(false, "Rendered views did not match. Outputs saved to \(markupURL.path()) and \(viewURL.path())")
+    }
+}