fix: harden iOS runner command execution

Author: thymikee

ios-runner/AgentDeviceRunner/AgentDeviceRunner.xcodeproj/project.pbxproj

@@ -401,6 +401,7 @@
 				STRING_CATALOG_GENERATE_SYMBOLS = NO;
 				SWIFT_APPROACHABLE_CONCURRENCY = YES;
 				SWIFT_EMIT_LOC_STRINGS = NO;
+				SWIFT_OBJC_BRIDGING_HEADER = "AgentDeviceRunnerUITests/AgentDeviceRunnerUITests-Bridging-Header.h";
 				SWIFT_UPCOMING_FEATURE_MEMBER_IMPORT_VISIBILITY = YES;
 				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
@@ -422,6 +423,7 @@
 				STRING_CATALOG_GENERATE_SYMBOLS = NO;
 				SWIFT_APPROACHABLE_CONCURRENCY = YES;
 				SWIFT_EMIT_LOC_STRINGS = NO;
+				SWIFT_OBJC_BRIDGING_HEADER = "AgentDeviceRunnerUITests/AgentDeviceRunnerUITests-Bridging-Header.h";
 				SWIFT_UPCOMING_FEATURE_MEMBER_IMPORT_VISIBILITY = YES;
 				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";

ios-runner/AgentDeviceRunner/AgentDeviceRunnerUITests/AgentDeviceRunnerUITests-Bridging-Header.h

@@ -0,0 +1 @@
+#import "RunnerObjCExceptionCatcher.h"

ios-runner/AgentDeviceRunner/AgentDeviceRunnerUITests/RunnerObjCExceptionCatcher.h

@@ -0,0 +1,11 @@
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface RunnerObjCExceptionCatcher : NSObject
+
++ (NSString * _Nullable)catchException:(NS_NOESCAPE dispatch_block_t)tryBlock;
+
+@end
+
+NS_ASSUME_NONNULL_END

ios-runner/AgentDeviceRunner/AgentDeviceRunnerUITests/RunnerObjCExceptionCatcher.m

@@ -0,0 +1,15 @@
+#import "RunnerObjCExceptionCatcher.h"
+
+@implementation RunnerObjCExceptionCatcher
+
++ (NSString * _Nullable)catchException:(NS_NOESCAPE dispatch_block_t)tryBlock {
+  @try {
+    tryBlock();
+    return nil;
+  } @catch (NSException *exception) {
+    NSString *reason = exception.reason ?: @"Unhandled XCTest exception";
+    return [NSString stringWithFormat:@"%@: %@", exception.name, reason];
+  }
+}
+
+@end

ios-runner/AgentDeviceRunner/AgentDeviceRunnerUITests/RunnerTests.swift

@@ -20,6 +20,7 @@ final class RunnerTests: XCTestCase {
   private let maxRequestBytes = 2 * 1024 * 1024
   private let maxSnapshotElements = 600
   private let fastSnapshotLimit = 300
+  private let mainThreadExecutionTimeout: TimeInterval = 30
   private let interactiveTypes: Set<XCUIElement.ElementType> = [
     .button,
     .cell,
@@ -49,7 +50,7 @@ final class RunnerTests: XCTestCase {
   ]
 
   override func setUp() {
-    continueAfterFailure = false
+    continueAfterFailure = true
   }
 
   @MainActor
@@ -192,19 +193,26 @@ final class RunnerTests: XCTestCase {
 
   private func execute(command: Command) throws -> Response {
     if Thread.isMainThread {
-      return try executeOnMain(command: command)
+      return try executeOnMainSafely(command: command)
     }
     var result: Result<Response, Error>?
     let semaphore = DispatchSemaphore(value: 0)
     DispatchQueue.main.async {
       do {
-        result = .success(try self.executeOnMain(command: command))
+        result = .success(try self.executeOnMainSafely(command: command))
       } catch {
         result = .failure(error)
       }
       semaphore.signal()
     }
-    semaphore.wait()
+    let waitResult = semaphore.wait(timeout: .now() + mainThreadExecutionTimeout)
+    if waitResult == .timedOut {
+      throw NSError(
+        domain: "AgentDeviceRunner",
+        code: 3,
+        userInfo: [NSLocalizedDescriptionKey: "main thread execution timed out"]
+      )
+    }
     switch result {
     case .success(let response):
       return response
@@ -215,24 +223,74 @@ final class RunnerTests: XCTestCase {
     }
   }
 
+  private func executeOnMainSafely(command: Command) throws -> Response {
+    var response: Response?
+    var swiftError: Error?
+    let exceptionMessage = RunnerObjCExceptionCatcher.catchException({
+      do {
+        response = try self.executeOnMain(command: command)
+      } catch {
+        swiftError = error
+      }
+    })
+
+    if let exceptionMessage {
+      currentApp = nil
+      currentBundleId = nil
+      throw NSError(
+        domain: "AgentDeviceRunner.NSException",
+        code: 1,
+        userInfo: [NSLocalizedDescriptionKey: exceptionMessage]
+      )
+    }
+    if let swiftError {
+      throw swiftError
+    }
+    guard let response else {
+      throw NSError(
+        domain: "AgentDeviceRunner",
+        code: 2,
+        userInfo: [NSLocalizedDescriptionKey: "command returned no response"]
+      )
+    }
+    return response
+  }
+
   private func executeOnMain(command: Command) throws -> Response {
+    if command.command == .shutdown {
+      return Response(ok: true, data: DataPayload(message: "shutdown"))
+    }
+
     let normalizedBundleId = command.appBundleId?
       .trimmingCharacters(in: .whitespacesAndNewlines)
     let requestedBundleId = (normalizedBundleId?.isEmpty == true) ? nil : normalizedBundleId
-    if let bundleId = requestedBundleId, currentBundleId != bundleId {
-      let target = XCUIApplication(bundleIdentifier: bundleId)
-      NSLog("AGENT_DEVICE_RUNNER_ACTIVATE bundle=%@ state=%d", bundleId, target.state.rawValue)
-      // activate avoids terminating and relaunching the target app
-      target.activate()
-      currentApp = target
-      currentBundleId = bundleId
-    } else if requestedBundleId == nil {
+    if let bundleId = requestedBundleId {
+      if currentBundleId != bundleId || currentApp == nil {
+        _ = activateTarget(bundleId: bundleId, reason: "bundle_changed")
+      }
+    } else {
       // Do not reuse stale bundle targets when the caller does not explicitly request one.
       currentApp = nil
       currentBundleId = nil
     }
-    let activeApp = currentApp ?? app
-    _ = activeApp.waitForExistence(timeout: 5)
+    var activeApp = currentApp ?? app
+    if let bundleId = requestedBundleId, targetNeedsActivation(activeApp) {
+      activeApp = activateTarget(bundleId: bundleId, reason: "stale_target")
+    } else if requestedBundleId == nil, targetNeedsActivation(activeApp) {
+      app.activate()
+      activeApp = app
+    }
+
+    if !activeApp.waitForExistence(timeout: 5) {
+      if let bundleId = requestedBundleId {
+        activeApp = activateTarget(bundleId: bundleId, reason: "missing_after_wait")
+        guard activeApp.waitForExistence(timeout: 5) else {
+          return Response(ok: false, error: ErrorPayload(message: "app '\(bundleId)' is not available"))
+        }
+      } else {
+        return Response(ok: false, error: ErrorPayload(message: "runner app is not available"))
+      }
+    }
 
     switch command.command {
     case .shutdown:
@@ -356,6 +414,30 @@ final class RunnerTests: XCTestCase {
     }
   }
 
+  private func targetNeedsActivation(_ target: XCUIApplication) -> Bool {
+    switch target.state {
+    case .unknown, .notRunning, .runningBackground, .runningBackgroundSuspended:
+      return true
+    default:
+      return false
+    }
+  }
+
+  private func activateTarget(bundleId: String, reason: String) -> XCUIApplication {
+    let target = XCUIApplication(bundleIdentifier: bundleId)
+    NSLog(
+      "AGENT_DEVICE_RUNNER_ACTIVATE bundle=%@ state=%d reason=%@",
+      bundleId,
+      target.state.rawValue,
+      reason
+    )
+    // activate avoids terminating and relaunching the target app
+    target.activate()
+    currentApp = target
+    currentBundleId = bundleId
+    return target
+  }
+
   private func tapNavigationBack(app: XCUIApplication) -> Bool {
     let buttons = app.navigationBars.buttons.allElementsBoundByIndex
     if let back = buttons.first(where: { $0.isHittable }) {