[apple] Failed to connect to port on device

[kotlarmilos]

Description

https://helix.dot.net/api/jobs/4cbf9a6d-6389-43f9-9e2c-16540105525e/workitems?api-version=2019-06-17

Both tests pass based on the logs, but one of them is unable to establish a connection via TCP, while the other establishes a connection every time. This failure seems to be permanent and could be a good starting point for identifying the issue.

When I attempted to reproduce the error locally, I encountered the same issue.

Repro steps

Host: osx-arm64
Device: iPhone iOS 16.5.1
Xcode: 14.3.1 (14E300c)

1. Install xharness locally (I don't believe it has anything with the repro, that is just my local setup):

# Using bash on Linux/MacOS
curl -L https://aka.ms/get-xharness | bash -

2. Download the bundle and place it in a test directory.
   tracing_eventpipe_tcp_issue.zip

3. Run the following script from the local directory:

./xharness apple test --app "<LOCAL_DIRECTORY>/tracing_eventpipe_tcp_issue.app" --target "ios-device" --output-directory "<LOCAL_DIRECTORY>/output" --set-env=MONO_APPLE_APP_ENTRY_POINT_LIB_NAME=testdir-buffersize/buffersize.dll --set-env=MONO_APPLE_APP_ASSEMBLY_LOAD_PREFIX=testdir-buffersize --xcode /Applications/Xcode.app -v --launch-timeout 00:05:00

The test should start executing and may fail (due to other reasons), but the TCP connection is not established. The app fails locally with

fail: Application test run crashed
      TCP Tunnel Connection Failed to connect to TCP port

Originally posted by @kotlarmilos in dotnet/runtime#82637 (comment)

[kotlarmilos]

For the apple test command, XHarness expects the application to contain a TestRunner which is a library you can find in this repository. This library executes unit tests similarly how you would execute them on other platforms. However, the TestRunner from this repository contains more mechanisms that help to work around some issues (mostly in Apple platforms).

The runtime test did not utilize the TestRunner, and it was expected to fail. After further investigation and monitoring of the CI, it appears that the TCP failures might be related to the app. If such a failure occurs, ensure that the app functions correctly or consider using apple run commands.