Add utility script to compare snapshot version updates

Scripts/CompareRenamedSnapshots.swift

@@ -0,0 +1,87 @@
+#!/usr/bin/swift
+
+// This script is designed to make it easier to review a large number of snapshot reference images that have been
+// recorded on a new iOS version, for which git does not identify the files as renames. It requires having Kaleidoscope
+// installed, including the ksdiff utility.
+//
+// Here is a sample workflow for updating reference images:
+//
+// 1. Add a new worktree and check out the commit that contains the most recent version of the old snapshots.
+//
+//     git worktree add ../AccessibilitySnapshot-snapshots-old <commit>
+//
+// 2. On your main worktree, add the new snapshots you wish to review.
+//
+// 3. Copy the image paths from the staging area to a text file.
+//
+// 4. Run this script with the appropriate paths and the relevant versions. For example, when updating snapshots from
+//    iOS 13.1 to 13.2.2, this would be:
+//
+//     ./Scripts/CompareRenamedSnapshots.swift /path/to/image/list.txt ../AccessibilitySnapshot-snapshots-old 13.2.2 13.1
+//
+// The script will open Kaleidoscope with each image pair in sequence (when you close one diff, the next will open).
+
+import Foundation
+
+enum TaskError: Error {
+	case code(Int32)
+}
+
+func execute(commandPath: String, arguments: [String]) throws {
+	let task = Process()
+	task.launchPath = commandPath
+	task.arguments = arguments
+
+	task.launch()
+
+	task.waitUntilExit()
+
+	guard task.terminationStatus == 0 else {
+		throw TaskError.code(task.terminationStatus)
+	}
+}
+
+if CommandLine.arguments.count < 5 || CommandLine.arguments[1] == "--help" || CommandLine.arguments[1] == "-h" {
+	print("usage: CompareRenamedSnapshots SNAPSHOT_LIST_FILE OLD_REPO_PATH NEW_DEVICE_ID OLD_DEVICE_ID")
+	exit(0)
+}
+
+let snapshotListFilePath = CommandLine.arguments[1]
+let snapshotImageList = String(data: NSData(contentsOfFile: snapshotListFilePath)! as Data, encoding: .utf8)!.split(separator: "\n")
+
+let oldRepoPath = CommandLine.arguments[2]
+
+let newDeviceId = CommandLine.arguments[3]
+let oldDeviceId = CommandLine.arguments[4]
+let newDeviceIdFBSnapshotTestCase = newDeviceId.replacingOccurrences(of: ".", with: "_")
+let oldDeviceIdFBSnapshotTestCase = oldDeviceId.replacingOccurrences(of: ".", with: "_")
+let newDeviceIdSnapshotTesting = newDeviceId.replacingOccurrences(of: ".", with: "-")
+let oldDeviceIdSnapshotTesting = oldDeviceId.replacingOccurrences(of: ".", with: "-")
+
+func ksdiff(oldFilePath: String, newFilePath: String, index: Int) throws {
+	guard newFilePath.contains(newDeviceIdFBSnapshotTestCase) || newFilePath.contains(newDeviceIdSnapshotTesting) else {
+		print("Skipping \(newFilePath) since there is it is of an unknown version")
+		return
+	}
+
+	print("Showing diff for \(newFilePath) (\(index+1) of \(snapshotImageList.count))")
+
+	try execute(
+		commandPath: "/usr/local/bin/ksdiff",
+		arguments: ["--wait", oldFilePath, newFilePath]
+	)
+}
+
+for (index, newFilePath) in snapshotImageList.enumerated() {
+	let oldFilePathInRepo = String(
+		newFilePath
+			.replacingOccurrences(of: newDeviceIdFBSnapshotTestCase, with: oldDeviceIdFBSnapshotTestCase)
+			.replacingOccurrences(of: newDeviceIdSnapshotTesting, with: oldDeviceIdSnapshotTesting)
+	)
+
+	do {
+		try ksdiff(oldFilePath: oldRepoPath + "/" + oldFilePathInRepo, newFilePath: String(newFilePath), index: index)
+	} catch {
+		print("Failed to diff \(newFilePath)")
+	}
+}