Initial Commit

.gitignore

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+.swiftpm
+.DS_Store

Package.resolved

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+{
+  "object": {
+    "pins": [
+      {
+        "package": "SnapshotTesting",
+        "repositoryURL": "https://github.com/pointfreeco/swift-snapshot-testing.git",
+        "state": {
+          "branch": null,
+          "revision": "f8a9c997c3c1dab4e216a8ec9014e23144cbab37",
+          "version": "1.9.0"
+        }
+      }
+    ]
+  },
+  "version": 1
+}

Package.swift

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+// swift-tools-version:5.3
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "swift-snapshot-testing-stitch",
+    platforms: [
+        .iOS(.v11),
+    ],
+    products: [
+        .library(
+            name: "swift-snapshot-testing-stitch",
+            targets: ["SnapshotTestingStitch"]
+        ),
+    ],
+    dependencies: [
+        .package(name: "SnapshotTesting",
+                 url: "https://github.com/pointfreeco/swift-snapshot-testing.git", from: "1.8.0"),
+    ],
+    targets: [
+        .target(
+            name: "SnapshotTestingStitch",
+            dependencies: [
+                .product(name: "SnapshotTesting", package: "SnapshotTesting"),
+            ]
+        ),
+
+        .testTarget(
+            name: "SnapshotTestingStitchTests",
+            dependencies: ["SnapshotTestingStitch"],
+            exclude: ["__Snapshots__"]
+        ),
+    ]
+)

README.md

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+# SnapshotTesting Stitch
+
+This is an extension to [SnapshotTesting](https://github.com/pointfreeco/swift-snapshot-testing) which allows you to create images combining the output of multiple snapshot strategies assuming they all output to UIImage.
+
+In essence, this allows you to have a single image which represents a single snapshotted value in multiple different configurations. This might be useful in situations, for example, where you have the same UIViewController and want a single image showing the view in multiple sizes.
+
+Images may also have titles, allowing you to easily identify each configuration within the image.
+
+## Usage
+
+See tests for example usage.

Sources/SnapshotTestingStitch/Snapshotting.swift

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+import UIKit
+import SnapshotTesting
+
+extension Snapshotting where Value == UIViewController, Format == UIImage {
+
+    public static func stitch(
+        strategies: [Snapshotting<Value, Format>],
+        style: StitchStyle = .init()
+    ) -> Snapshotting {
+        // Default to an empty string, if they choose not to provide one.
+        stitch(strategies: strategies.map { ("", $0) }, style: style)
+    }
+
+    public static func stitch(
+        strategies: [(name: String, strategy: Snapshotting<Value, Format>)],
+        style: StitchStyle = .init()
+    ) -> Snapshotting {
+        let internalStrategy: Snapshotting<UIViewController, UIImage> = .image
+
+        return Snapshotting(
+            pathExtension: internalStrategy.pathExtension,
+            diffing: internalStrategy.diffing
+        ) { value in
+            Async<UIImage> { callback in
+                // Create a dispatch group to keep track of the remaining tasks
+                let dispatchGroup = DispatchGroup()
+
+                // Create an array to store the final outputs to be stitched
+                var values = [(String, UIImage)]()
+
+                // Loop over each of the user-provided strategies, snapshot them,
+                // store the output, and update the dispatch group.
+                strategies.forEach { strategy in
+                    dispatchGroup.enter()
+
+                    strategy.strategy.snapshot(value).run { output in
+                        values.append((strategy.name, output))
+                        dispatchGroup.leave()
+                    }
+                }
+
+                // Once all strategies have been completed...
+                dispatchGroup.notify(queue: .main) {
+                    // Sort values based on input order
+                    let comparableValues = strategies.compactMap { (name, _) in
+                        values.first(where: { $0.0 == name })
+                    }
+
+                    // Stitch them together, and callback to the snapshot testing library.
+                    let image = ImageStitcher(inputs: comparableValues).stitch(style: style)
+                    callback(image)
+                }
+            }
+        }
+    }
+
+}

Sources/SnapshotTestingStitch/StitchStyle.swift

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+import UIKit
+
+public struct StitchStyle {
+    /// How large should the font size be for the optional titles which appear above each stitched image?
+    public let fontSize: CGFloat
+
+    /// What color should the border be which surrounds each individual stitched image?
+    public let borderColor: UIColor
+
+    /// How thick should the border be which surrounds each individual stitched image?
+    public let borderWidth: CGFloat
+
+    /// How far apart should each stitched image be from another?
+    public let itemSpacing: CGFloat
+
+    /// Creates a defintion of how a stitched snapshot should be presented.
+    ///
+    /// Allows you to customise certain aspects of the stitched output image.
+    ///
+    /// - Parameters:
+    ///     - fontSize: How large should the font size be for the optional titles which appear above each stitched image?
+    ///     - borderColor: What color should the border be which surrounds each individual stitched image?
+    ///     - borderWidth: How thick should the border be which surrounds each individual stitched image?
+    ///     - itemSpacing: How far apart should each stitched image be from another?
+    public init(
+        fontSize: CGFloat = 20,
+        borderColor: UIColor = .red,
+        borderWidth: CGFloat = 5,
+        itemSpacing: CGFloat = 32
+    ) {
+        assert(borderWidth >= 0, "The provided border width should be a positive integer, or zero if you do not want a border to be displayed.")
+        assert(itemSpacing >= 0, "The provided item spacing should be a positive integer.")
+        assert(fontSize >= 0, "The provided font size should be a positive integer.")
+
+        self.fontSize = fontSize
+        self.borderColor = borderColor
+        self.borderWidth = borderWidth
+        self.itemSpacing = itemSpacing
+    }
+
+}

Sources/SnapshotTestingStitch/Stitcher.swift

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+import UIKit
+
+struct ImageStitcher {
+
+    let inputs: [(title: String, image: UIImage)]
+
+    func stitch(style: StitchStyle) -> UIImage {
+
+        let includeTitles: Bool = inputs.map { $0.title }.allSatisfy { $0 == "" } == false
+        let images = inputs.map { $0.image }
+
+        // Calculate how large the full image will be based on the inputs
+        let framePadding: CGFloat = style.itemSpacing
+
+        let largestHeight = images.map { $0.size.height }.max() ?? 0
+        let computedHeight =
+            largestHeight +
+            (includeTitles ? style.fontSize + framePadding : 0) + // Title Size
+            (style.borderWidth * 2) + // Vertical Border
+            (framePadding * 2) // Vertical Padding
+
+        let imageSumWidth = images.map {
+            $0.size.width +
+            (style.borderWidth * 2) + // Horizontal Border
+            style.itemSpacing // Horizontal Interitem Spacing
+        }.reduce(0, +)
+
+        let computedWidth =
+            imageSumWidth +
+            (framePadding * 2) - // Horizontal Padding
+            style.itemSpacing // Remove Final Image's Interitem Spacing
+
+        // Create renderer with correct image size
+        let computedSize = CGSize(
+            width: computedWidth,
+            height: computedHeight
+        )
+
+        let renderer = UIGraphicsImageRenderer(size: computedSize)
+
+        // Setup title styling
+        let paragraphStyle = NSMutableParagraphStyle()
+        paragraphStyle.alignment = .center
+
+        let titleAttributes: [NSAttributedString.Key: Any] = [
+            .font: UIFont.systemFont(ofSize: style.fontSize),
+            .paragraphStyle: paragraphStyle,
+            .foregroundColor: UIColor.white
+        ]
+
+        // Draw the image
+        let image = renderer.image { context in
+            context.cgContext.setFillColor(UIColor.black.cgColor)
+            context.cgContext.fill(CGRect(origin: .zero, size: computedSize))
+
+            var xOffset = framePadding + style.borderWidth
+            var yOffset = framePadding + style.borderWidth
+
+            // If we have a title to display, then we'll increase the yOffset to leave space at the top
+            if includeTitles {
+                yOffset += style.fontSize + framePadding
+            }
+
+            inputs.forEach { (title, image) in
+                // Draw Border
+                context.cgContext.setFillColor(style.borderColor.cgColor)
+                context.cgContext.setStrokeColor(style.borderColor.cgColor)
+                context.cgContext.setLineWidth(style.borderWidth)
+
+                context.cgContext.addRect(CGRect(
+                    x: xOffset,
+                    y: yOffset,
+                    width: image.size.width + (style.borderWidth * 2),
+                    height: image.size.height + (style.borderWidth * 2)
+                ))
+
+                context.cgContext.drawPath(using: .fillStroke)
+
+                // Draw Image
+                image.draw(at: CGPoint(
+                    x: xOffset + style.borderWidth,
+                    y: yOffset + style.borderWidth
+                ))
+
+                // Draw Title
+                if title.isEmpty == false {
+                    title.draw(
+                        with: CGRect(
+                            x: xOffset,
+                            y: framePadding,
+                            width: image.size.width,
+                            height: image.size.height
+                        ),
+                        options: .usesLineFragmentOrigin,
+                        attributes: titleAttributes,
+                        context: nil
+                    )
+                }
+
+                // Increment horizontal offset for next image
+                xOffset +=
+                    image.size.width +
+                    style.itemSpacing +
+                    (style.borderWidth * 2)
+            }
+        }
+
+        return image
+    }
+
+}

Tests/SnapshotTestingStitchTests/SnapshotTestingStitch.swift

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+import XCTest
+import SnapshotTesting
+@testable import SnapshotTestingStitch
+
+final class SnapshotTestingStitchTests: XCTestCase {
+
+    let isRecording: Bool = false
+
+    func test_withTitles() {
+        assertSnapshot(
+            matching: createTestViewController(),
+            as: .stitch(
+                strategies: [
+                    ("iPhone 8", .image(on: .iPhone8)),
+                    ("iPhone 8 Plus", .image(on: .iPhone8Plus)),
+                ]
+            ),
+            record: isRecording
+        )
+    }
+
+    func test_withoutTitles() {
+        assertSnapshot(
+            matching: createTestViewController(),
+            as: .stitch(
+                strategies: [
+                    .image(on: .iPhone8),
+                    .image(on: .iPhone8Plus),
+                ]
+            ),
+            record: isRecording
+        )
+    }
+
+    func test_withoutBorder() {
+        assertSnapshot(
+            matching: createTestViewController(),
+            as: .stitch(
+                strategies: [
+                    ("iPhone 8", .image(on: .iPhone8)),
+                    ("iPhone 8 Plus", .image(on: .iPhone8Plus)),
+                ],
+                style: .init(borderWidth: 0)
+            ),
+            record: isRecording
+        )
+    }
+
+    func test_withManyDevices() {
+        assertSnapshot(
+            matching: createTestViewController(),
+            as: .stitch(
+                strategies: [
+                    ("iPhone 8", .image(on: .iPhone8)),
+                    ("iPhone 8 Plus", .image(on: .iPhone8Plus)),
+                    ("iPhone X", .image(on: .iPhoneX)),
+                    ("iPhone SE", .image(on: .iPhoneSe)),
+                    ("iPhone Xr", .image(on: .iPhoneXr)),
+                    ("iPhone Xs Max", .image(on: .iPhoneXsMax)),
+                    ("iPhone Xs Max (Landscape)", .image(on: .iPhoneXsMax(.landscape))),
+                ]
+            ),
+            record: isRecording
+        )
+    }
+
+    // MARK: - Helpers
+
+    func createTestViewController() -> UIViewController {
+        let viewController = UIViewController()
+        viewController.view.backgroundColor = .blue
+
+        return viewController
+    }
+
+}