Write out changes instead of merging with input

Sources/ValidatorCore/Commands/CheckRedirects.swift

@@ -32,8 +32,11 @@ extension Validator {
         @Option(name: .long, help: "start processing URLs from <offset>")
         var offset: Int = 0
 
-        @Option(name: .shortAndLong, help: "save changes to output file")
-        var output: String?
+        @Option(name: .shortAndLong, help: "output file for added packages")
+        var outputAdded: String?
+
+        @Option(name: .shortAndLong, help: "output file for removed packages")
+        var outputRemoved: String?
 
         @Flag(name: .long, help: "check redirects of canonical package list")
         var usePackageList = false
@@ -71,10 +74,34 @@ extension Validator {
 
         static var normalizedPackageURLs = NormalizedPackageURLs(inputURLs: [])
 
+        enum Change: Equatable {
+            case add(PackageURL)
+            case keep(PackageURL)
+            case remove(PackageURL)
+
+            var added: PackageURL? {
+                switch self {
+                    case let .add(url):
+                        return url
+                    case .keep, .remove:
+                        return nil
+                }
+            }
+
+            var removed: PackageURL? {
+                switch self {
+                    case let .remove(url):
+                        return url
+                    case .add, .keep:
+                        return nil
+                }
+            }
+        }
+
         static func process(redirect: Redirect,
                             verbose: Bool,
                             index: Int,
-                            packageURL: PackageURL) async throws -> PackageURL? {
+                            packageURL: PackageURL) async throws -> Change {
             if verbose || index % 50 == 0 {
                 print("package \(index) ...")
                 fflush(stdout)
@@ -84,29 +111,29 @@ extension Validator {
                     if verbose {
                         print("        \(packageURL.absoluteString)")
                     }
-                    return packageURL
+                    return .keep(packageURL)
                 case let .error(error):
                     print("ERROR: \(packageURL.absoluteString) \(error) (ignored, keeping package)")
                     // don't skip packages that have unrecognised errors
-                    return packageURL
+                    return .keep(packageURL)
                 case .notFound:
                     print("package \(index) ...")
                     print("NOT FOUND: \(packageURL.absoluteString) (deleting package)")
-                    return nil
+                    return .remove(packageURL)
                 case .rateLimited:
                     fatalError("rate limited - should have been retried at a lower level")
                 case .redirected(let url):
                     if await normalizedPackageURLs.insert(url).inserted {
                         print("ADD \(packageURL) -> \(url) (new)")
-                        return url
+                        return .add(url)
                     } else {
                         print("DELETE \(packageURL) -> \(url) (exists)")
-                        return nil
+                        return .remove(packageURL)
                     }
                 case .unauthorized:
                     print("package \(index) ...")
                     print("UNAUTHORIZED: \(packageURL.absoluteString) (deleting package)")
-                    return nil
+                    return .remove(packageURL)
             }
         }
 
@@ -139,7 +166,7 @@ extension Validator {
 
             let semaphore = Semaphore(maximum: concurrency ?? 1)
 
-            let updated = try await withThrowingTaskGroup(of: PackageURL?.self) { group in
+            let changes = try await withThrowingTaskGroup(of: Change.self) { group in
                 for (index, packageURL) in inputURLs[offset...]
                     .prefix(prefix)
                     .chunk(index: chunk, of: numberOfChunks)
@@ -168,16 +195,16 @@ extension Validator {
                         return res
                     }
                 }
-                return try await group
-                    .compactMap { $0 }
-                    .reduce(into: [], { res, next in res.append(next) })
-                    .sorted(by: { $0.lowercased() < $1.lowercased() })
+                return try await group.reduce(into: [], { res, next in res.append(next) })
+            }
+
+            if let path = outputAdded {
+                try Current.fileManager.saveList(changes.compactMap(\.added), path: path)
             }
 
-            if let path = output {
-                try Current.fileManager.saveList(updated, path: path)
+            if let path = outputRemoved {
+                try Current.fileManager.saveList(changes.compactMap(\.removed), path: path)
             }
         }
     }
 }
-

Tests/ValidatorTests/CheckRedirectTests.swift

@@ -28,7 +28,7 @@ final class CheckRedirectTests: XCTestCase {
                                                              verbose: true,
                                                              index: 0,
                                                              packageURL: .p1)
-        XCTAssertEqual(res, .p2)
+        XCTAssertEqual(res, .add(.p2))
     }
 
     func test_process_existing_redirect() async throws {
@@ -40,7 +40,7 @@ final class CheckRedirectTests: XCTestCase {
                                                              verbose: true,
                                                              index: 0,
                                                              packageURL: .p1)
-        XCTAssertEqual(res, nil)
+        XCTAssertEqual(res, .remove(.p1))
     }
 
 }