Support @Previewable macro

Example/PreFireExample.xcodeproj/project.pbxproj

@@ -200,7 +200,7 @@
 					};
 				};
 			};
-			buildConfigurationList = 9735EE26289C5CF200309267 /* Build configuration list for PBXProject "PreFireExample" */;
+			buildConfigurationList = 9735EE26289C5CF200309267 /* Build configuration list for PBXProject "PrefireExample" */;
 			compatibilityVersion = "Xcode 13.0";
 			developmentRegion = en;
 			hasScannedForEncodings = 0;
@@ -534,7 +534,7 @@
 /* End XCBuildConfiguration section */
 
 /* Begin XCConfigurationList section */
-		9735EE26289C5CF200309267 /* Build configuration list for PBXProject "PreFireExample" */ = {
+		9735EE26289C5CF200309267 /* Build configuration list for PBXProject "PrefireExample" */ = {
 			isa = XCConfigurationList;
 			buildConfigurations = (
 				9735EE3E289C5CF300309267 /* Debug */,

Example/Shared/Examples/PrefireView.swift

@@ -41,7 +41,10 @@ struct PrefireView_Preview: PreviewProvider, PrefireProvider {
 }
 
 #Preview("PrefireViewMacroAnother") {
+    @Previewable @State var title: String = "Prefire"
+
     PrefireView()
+        .navigationTitle(title)
         .previewUserStory(.auth)
         .snapshot(perceptualPrecision: 0.98)
 }

PrefireExecutable/Sources/prefire/Extensions/String+Rewrite.swift → PrefireExecutable/Sources/prefire/Extensions/String+Extensions.swift

@@ -19,4 +19,12 @@ extension String {
             fatalError(error.localizedDescription)
         }
     }
+
+    /// Indents the lines in the receiver
+    ///
+    /// - Parameters:
+    ///   - amount: A int specifies the amount of indentString for one level idnentation
+    func ident(_ count: Int) -> String {
+        components(separatedBy: "\n").map({ String(repeating: " ", count: count) + $0 }).joined(separator: "\n")
+    }
 }

PrefireExecutable/Sources/prefire/Previews/PreviewLoader+Playbook.swift

@@ -2,7 +2,6 @@ import Foundation
 
 extension PreviewLoader {
     private static let yamlSettings = "|-4\n\n"
-    private static let previewSpaces = "                    "
 
     /// Loading and creating lines of code with the `PreviewModel` array
     /// - Parameters:
@@ -13,15 +12,17 @@ extension PreviewLoader {
         guard let findedBodies = await loadRawPreviewBodies(for: sources, defaultEnabled: defaultEnabled) else { return nil }
 
         let previewModels = findedBodies
-            .compactMap { RawPreviewModel(from: $0.value, filename: $0.key, lineSymbol: previewSpaces)?.previewModel }
-            .joined(separator: "\n")
+            .sorted { $0.key > $1.key }
+            .compactMap { RawPreviewModel(from: $0.value, filename: $0.key) }
 
         return yamlSettings +
             """
                 @MainActor
                 private struct MacroPreviews {
+                \(previewModels.filter({ $0.properties != nil }).map({ $0.previewWrapper }).joined(separator: "\r\n"))
+
                     static var previews: [PreviewModel] = [
-            \(previewModels)
+            \(previewModels.map(\.previewModel).joined(separator: "\r\n"))
                     ]
                 }
             """

PrefireExecutable/Sources/prefire/Previews/PreviewLoader+Tests.swift

@@ -3,32 +3,40 @@ import Foundation
 extension PreviewLoader {
     private static let funcCharacterSet = CharacterSet(arrayLiteral: "_").inverted.intersection(.alphanumerics.inverted)
     private static let yamlSettings = "|-4\n\n"
-    private static let previewSpaces = "            "
 
     static func loadPreviewBodies(for sources: [String], defaultEnabled: Bool) async -> String? {
-        guard let findedBodies = await loadRawPreviewBodies(for: sources, defaultEnabled: defaultEnabled) else { return nil }
-
-        let result = findedBodies
-            .sorted(by: { $0.key > $1.key })
-            .compactMap { makeFunc(fileName: $0.key, body: $0.value)?.appending("\r\n") }
-            .joined()
-
-        return yamlSettings + result
+        guard let rawBodies = await loadRawPreviewBodies(for: sources, defaultEnabled: defaultEnabled) else { return nil }
+        
+        let functions = rawBodies
+            .sorted { $0.key > $1.key }
+            .compactMap { makeTestFunc(fileName: $0.key, body: $0.value) }
+            .joined(separator: "\r\n")
+        
+        return yamlSettings + functions
     }
 
-    private static func makeFunc(fileName: String, body: String) -> String? {
-        guard let rawPreviewModel = RawPreviewModel(from: body, filename: fileName, lineSymbol: previewSpaces) else { return nil }
-        let isScreen = rawPreviewModel.traits == ".device"
-        let componentTestName = rawPreviewModel.displayName.components(separatedBy: funcCharacterSet).joined()
-        let snapshotSettings = rawPreviewModel.snapshotSettings?.replacingOccurrences(of: "snapshot", with: "init")
-
-        return 
-            """
+    private static func makeTestFunc(fileName: String, body: String) -> String? {
+        guard let model = RawPreviewModel(from: body, filename: fileName) else { return nil }
+
+        let componentTestName = model.displayName.components(separatedBy: funcCharacterSet).joined()
+        let settingsSuffix = (model.snapshotSettings?.replacingOccurrences(of: "snapshot", with: "init")).flatMap { ", settings: \($0)" } ?? ""
+
+        let previewCode: String
+        let content: String
+        if model.properties == nil {
+            previewCode = "        let preview = {\n\(model.body.ident(12))\n            }"
+            content = "preview()"
+        } else {
+            previewCode = model.previewWrapper.ident(4)
+            content = "PreviewWrapper\(model.displayName)()"
+        }
+
+        let prefireSnapshot = "PrefireSnapshot(\(content), name: \"\(model.displayName)\", isScreen: \(model.isScreen), device: deviceConfig\(settingsSuffix))"
+
+        return """
                     func test_\(componentTestName)_Preview() {
-                        let preview = {
-            \(rawPreviewModel.body)
-                        }
-                        if let failure = assertSnapshots(for: PrefireSnapshot(preview(), name: "\(rawPreviewModel.displayName)", isScreen: \(isScreen), device: deviceConfig\(snapshotSettings.flatMap({ ", settings: " + $0 }) ?? ""))) {
+                \(previewCode)
+                        if let failure = assertSnapshots(for: \(prefireSnapshot)) {
                             XCTFail(failure)
                         }
                     }

PrefireExecutable/Sources/prefire/Previews/RawPreviewModel.swift

@@ -4,14 +4,20 @@ struct RawPreviewModel {
     var displayName: String
     var traits: String
     var body: String
+    var properties: String?
     var snapshotSettings: String?
+
+    var isScreen: Bool {
+        traits == Constants.defaultTrait
+    }
 }
 
 extension RawPreviewModel {
     private enum Markers {
         static let previewMacro = "#Preview"
         static let traits = "traits: "
         static let snasphotSettings = ".snapshot("
+        static let previewable = "@Previewable"
     }
 
     private enum Constants {
@@ -22,10 +28,9 @@ extension RawPreviewModel {
     /// - Parameters:
     ///   - macroBody: Preview View body
     ///   - filename: File name in which the macro was found
-    ///   - lineSymbol: The line separator symbol
-    init?(from macroBody: String, filename: String, lineSymbol: String = "") {
-        let lines = macroBody.split(separator: "\n", omittingEmptySubsequences: false)
-        guard let firstLine = lines.first else { return nil }
+    init?(from macroBody: String, filename: String) {
+        var lines = macroBody.split(separator: "\n", omittingEmptySubsequences: false).dropLast(2)
+        let firstLine = lines.removeFirst()
 
         // Define displayName by splitting the first line by "
         let parts = firstLine.split(separator: "\"")
@@ -45,25 +50,42 @@ extension RawPreviewModel {
         }
         self.traits = previewTrait ?? Constants.defaultTrait
 
-        // Search for the line with snapshot settings
-        if let configLine = lines.first(where: { $0.contains(Markers.snasphotSettings) }) {
-            self.snapshotSettings = configLine.trimmingCharacters(in: .whitespaces)
-        } else {
-            self.snapshotSettings = nil
+
+        for (index, line) in lines.enumerated() {
+            // Search for the line with snapshot settings
+            if snapshotSettings == nil, line.contains(Markers.snasphotSettings) {
+                self.snapshotSettings = line.trimmingCharacters(in: .whitespaces)
+            } else if line.contains(Markers.previewable) {
+                lines.remove(at: index + 1)
+                if self.properties == nil {
+                    self.properties = String(line.replacing("\(Markers.previewable) ", with: ""))
+                } else {
+                    self.properties! += "\n" + String(line.replacing(Markers.previewable, with: ""))
+                }
+            }
         }
 
-        // Forming the Preview body: remove the first and last two lines
-        let bodyLines = lines.dropFirst().dropLast(2)
-        self.body = bodyLines.map { lineSymbol + $0 }.joined(separator: "\n")
+        self.body = lines.joined(separator: "\n")
     }
 }
 
 extension RawPreviewModel {
+    var previewWrapper: String {
+        """
+            struct PreviewWrapper\(displayName): SwiftUI.View {
+                \(properties ?? "")
+                    var body: some SwiftUI.View {
+        \(body.ident(12))
+                    }
+                }
+        """
+    }
+
     var previewModel: String {
         """
                     PreviewModel(
                         content: {
-        \(body)
+        \(properties == nil ? body.ident(16) : "                    PreviewWrapper\(displayName)()")
                         },
                         name: \"\(displayName)\",
                         type: \(traits == ".device" ? ".screen" : ".component")

PrefireExecutable/Tests/PrefireTests/RawPreviewModelTests.swift

@@ -13,23 +13,30 @@ class RawPreviewModelTests: XCTestCase {
         let rawPreviewModel = RawPreviewModel(from: previewBodyWithName, filename: "Test")
 
         XCTAssertEqual(rawPreviewModel?.body, "    Text(\"TestView\")")
+        XCTAssertEqual(rawPreviewModel?.properties, nil)
         XCTAssertEqual(rawPreviewModel?.displayName, "TestViewName")
         XCTAssertEqual(rawPreviewModel?.traits, ".sizeThatFitsLayout")
+        XCTAssertEqual(rawPreviewModel?.snapshotSettings, nil)
     }
 
     func test_initWithoutName() {
         let previewBodyWithoutName = """
         #Preview(traits: .sizeThatFitsLayout) {
+            @Previewable @State var name: String = "TestView"
+
             VStack {
-                Text("TestView")
+                Text(name)
             }
+            .snapshot(delay: 8)
         }
 
         """
         let rawPreviewModel = RawPreviewModel(from: previewBodyWithoutName, filename: "TestView")
-
-        XCTAssertEqual(rawPreviewModel?.body, "    VStack {\n        Text(\"TestView\")\n    }")
+
+        XCTAssertEqual(rawPreviewModel?.body, "\n    VStack {\n        Text(name)\n    }\n    .snapshot(delay: 8)")
+        XCTAssertEqual(rawPreviewModel?.properties, "    @State var name: String = \"TestView\"")
         XCTAssertEqual(rawPreviewModel?.displayName, "TestView")
         XCTAssertEqual(rawPreviewModel?.traits, ".sizeThatFitsLayout")
+        XCTAssertEqual(rawPreviewModel?.snapshotSettings, ".snapshot(delay: 8)")
     }
 }

Sources/Prefire/Preview/PreviewModel.swift

@@ -57,7 +57,7 @@ public struct PreviewModel: Identifiable {
     @MainActor
     public init(
         id: String? = nil,
-        content: @escaping () -> any View,
+        @ViewBuilder content: @escaping @MainActor () -> any View,
         name: String,
         type: LayoutType = .component,
         device: PreviewDevice? = nil,