Prerequisites

• Xcode 16 is available in CIPD
• Upgrade 50% of chromium bots to macOS 14.5 #148891 (assuming Xcode 16 requires macOS 14.5)
  • If Xcode 16 requires a higher macOS version, bots will need to be upgraded to new required version before doing this

Instructions

Make a PR that changes the .ci.yaml to use the new Xcode build version and run exclusively on macOS 14. Note that not all tests run in presubmit, so you'll likely need to do some of them via led or edit the .ci.yaml to run the tests in presubmit.

https://github.com/flutter/packages/blob/main/.ci.yaml

$flutter/osx_sdk : >-
        {
-          "sdk_version": "15a240d"
           "sdk_version": "[insert new CIPD case-sensitive Xcode build version]"
        }
        
- os: Mac-13|Mac-14
  os: Mac-14

https://github.com/flutter/packages/blob/main/.ci/scripts/create_simulator.sh

- readonly OS=com.apple.CoreSimulator.SimRuntime.iOS-17-0
  readonly OS=com.apple.CoreSimulator.SimRuntime.iOS-18-0

https://github.com/flutter/packages/blob/main/.ci/targets/ios_platform_tests.yaml

- args: ["native-test", "--ios", "--ios-destination", "platform=iOS Simulator,name=Flutter-iPhone,OS=17.0"]
  args: ["native-test", "--ios", "--ios-destination", "platform=iOS Simulator,name=Flutter-iPhone,OS=18.0"]

https://github.com/flutter/packages/blob/main/packages/pigeon/tool/shared/test_suites.dart

-  const String deviceRuntime = 'com.apple.CoreSimulator.SimRuntime.iOS-17-0';
-  const String deviceOS = '17.0';
   const String deviceRuntime = 'com.apple.CoreSimulator.SimRuntime.iOS-18-0';
   const String deviceOS = '18.0';

To run tests using led, such as for tests that don't run in presubmit, you can use a command like the following to test against the PR:

1. led get-builder "luci.flutter.staging:Mac_arm64 ios_platform_tests_shard_3 stable" > properties.json
2. Replace "sdk_version": "15a240d" with new Xcode build version (case sensitive with CIPD version)
3. cat properties.json | led edit -d os=Mac-14 | led edit -pa git_ref='refs/pull/[insert PR id]/head' | led edit -pa git_url='https://github.com/flutter/packages | led edit-recipes-bundle | led launch

❗ File issues for tests that fail and add links to the issues in #148898. This is important so we can track any fixes that need to be cherrypicked to beta/stable and so steps that are steps are not completed before issues are resolved.