Delete Printer: a queue that's already gone is a successful delete

Judge the delete by the read-back (is the queue gone?) instead of lpadmin's exit
status. Deleting a queue that was removed elsewhere before the sidebar refreshed
made lpadmin fail with 'The printer or class does not exist', and the app showed a
failure alert although the queue was gone. Now the status bar shows 'Deleted <queue>'
and os_log notes it was already deleted. Unit tests for all four outcomes, plus an
opt-in live test (CUPSKIT_LIVE_DELETE=1) on a name that never existed.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -68,7 +68,7 @@ swift build                          # debug build of everything
   verifies both BOM ownership entries. The app is notarized and stapled before packaging; the PKG after.
 - The app icon master is `Icon/AppIcon-1024.png`; `build.sh` generates `AppIcon.icns` from it. Don't redraw it.
 - Live tests are opt-in and write to queues: `CUPSKIT_LIVE_QUEUE=<queue>`, `CUPSKIT_LIVE_JOBS=<a>,<b>`,
-  `CUPSKIT_LIVE_QUICK=<ricoh>,<generic>`. Use throwaway queues (e.g. `lpd://127.0.0.1/…`, paused) and
+  `CUPSKIT_LIVE_QUICK=<ricoh>,<generic>`, `CUPSKIT_LIVE_DELETE=1` (deletes a queue name that never existed; writes nothing). Use throwaway queues (e.g. `lpd://127.0.0.1/…`, paused) and
   delete them afterwards; the live tests restore what they change. Offline tests use vendor PPDs from
   `CUPSKIT_PPD_DIRS` (colon-separated, e.g. Canon/HP PPDs extracted with `pkgutil --expand-full`, not
   installed) and `/Library/Printers/PPDs`, and skip when they aren't there.

Sources/CUPSAdminApp/PrinterStore.swift

@@ -251,7 +251,7 @@ final class PrinterStore {
             deleted = outcome.succeeded
             if deleted {
                 report("Deleted \(queue) in \(elapsedText(since: started))")
-                log.info("deleted \(queue, privacy: .public)")
+                log.info("deleted \(queue, privacy: .public)\(outcome.message.map { " (\($0))" } ?? "", privacy: .public)")
             } else {
                 report("ERROR: delete \(queue): \(outcome.message ?? "failed")")
                 fail("Couldn’t delete \(queue)", "\(outcome.message ?? "failed")\n\n\(outcome.command)")

Sources/CupsKit/QueueActions.swift

@@ -222,12 +222,21 @@ extension QueueActions {
     /// `lpadmin -x queue`, verified by the queue being gone.
     public static func delete(queue: String, client: CupsClient) async throws -> ActionOutcome {
         let result = try await Task.detached { try CupsTools.delete(queue: queue) }.value
-        guard result.succeeded else {
+        return deleteOutcome(queue: queue, result: result, stillExists: try await client.queueExists(queue))
-            return ActionOutcome(succeeded: false, command: result.commandLine, message: result.message.isEmpty ? "exited \(result.status)" : result.message)
     }
-        let stillThere = try await client.queueExists(queue)
+
-        return ActionOutcome(succeeded: !stillThere, command: result.commandLine,
+    /// Judged by the read-back, not lpadmin's exit status: the goal is that the queue is gone. A queue that
-                             message: stillThere ? "Not applied: \(queue) still exists" : nil)
+    /// was already deleted (by another app, lpadmin, or a row the sidebar hadn't refreshed yet) makes
+    /// lpadmin fail with "The printer or class does not exist" — that's still a successful delete.
+    /// `message` is set on success only in that case ("already deleted").
+    static func deleteOutcome(queue: String, result: ToolResult, stillExists: Bool) -> ActionOutcome {
+        if stillExists {
+            let message = result.succeeded ? "Not applied: \(queue) still exists"
+                : result.message.isEmpty ? "exited \(result.status)" : result.message
+            return ActionOutcome(succeeded: false, command: result.commandLine, message: message)
+        }
+        return ActionOutcome(succeeded: true, command: result.commandLine,
+                             message: result.succeeded ? nil : "\(queue) was already deleted")
     }
 
     /// Sends the CUPS test page (or a generated one-page PDF when it's missing). Returns the job id when verified.

Tests/CupsKitTests/QueueActionsTests.swift

@@ -1,4 +1,4 @@
-import CupsKit
+@testable import CupsKit
 import Foundation
 import Testing
 
@@ -57,3 +57,45 @@ struct LiveQueueActions {
         }
     }
 }
+
+/// Delete is judged by whether the queue is gone afterwards, not by lpadmin's exit status.
+@Suite struct DeleteReadBack {
+    private func result(_ status: Int32, _ stderr: String = "") -> ToolResult {
+        ToolResult(executable: CupsTools.lpadminPath, arguments: ["-x", "Old_Queue"], status: status,
+                   standardOutput: Data(), standardError: Data(stderr.utf8))
+    }
+
+    @Test func deletedNormally() {
+        let outcome = QueueActions.deleteOutcome(queue: "Old_Queue", result: result(0), stillExists: false)
+        #expect(outcome == ActionOutcome(succeeded: true, command: "/usr/sbin/lpadmin -x Old_Queue", message: nil))
+    }
+
+    /// The reported bug: the queue was removed elsewhere before Delete Printer ran, lpadmin said
+    /// "The printer or class does not exist", and the app showed a failure alert.
+    @Test func alreadyGoneIsASuccess() {
+        let outcome = QueueActions.deleteOutcome(queue: "Old_Queue",
+                                                 result: result(1, "lpadmin: The printer or class does not exist."),
+                                                 stillExists: false)
+        #expect(outcome.succeeded)
+        #expect(outcome.message == "Old_Queue was already deleted")
+    }
+
+    @Test func failureWhileQueueRemainsShowsToolOutput() {
+        let outcome = QueueActions.deleteOutcome(queue: "Old_Queue", result: result(1, "lpadmin: Forbidden"), stillExists: true)
+        #expect(!outcome.succeeded && outcome.message == "lpadmin: Forbidden")
+    }
+
+    @Test func exitZeroButStillThereIsNotApplied() {
+        let outcome = QueueActions.deleteOutcome(queue: "Old_Queue", result: result(0), stillExists: true)
+        #expect(!outcome.succeeded && outcome.message == "Not applied: Old_Queue still exists")
+    }
+
+    /// Opt-in (CUPSKIT_LIVE_DELETE=1): the real lpadmin and cupsd on a name that never existed. Writes nothing.
+    @Test(.enabled(if: ProcessInfo.processInfo.environment["CUPSKIT_LIVE_DELETE"] != nil))
+    func liveDeleteOfMissingQueue() async throws {
+        let name = "cupsadmin_missing_\(UInt32.random(in: 0 ... .max))"
+        let outcome = try await QueueActions.delete(queue: name, client: CupsClient())
+        #expect(outcome.succeeded, "\(outcome)")
+        #expect(outcome.message == "\(name) was already deleted")
+    }
+}