[iOS sim] Ensure simulator device is booted in iossim_prepare.py

[yln]

Summary

Recent versions of the iOS simulator require that a "simulator device"
is booted before we can use simctl spawn (see iossim_run.py) to start
processes.

We can use simctl bootstatus to ensure that the simulator device
is booted before we run any tests via lit. The -b option starts the
device if necessary.

[delcypher]

LGTM except the possible improvement to the error message.

compiler-rt/test/sanitizer_common/ios_commands/iossim_prepare.py

23

Suggested (but optional improvement). If the command fails print an error message that explains the command to run to boot the iOS simulator.

[yln]

compiler-rt/test/sanitizer_common/ios_commands/iossim_prepare.py

23

The command will boot the simulator (the -b flag ).

This is the error for an invalid device:

➤ env SANITIZER_IOSSIM_TEST_DEVICE_IDENTIFIER="iPhone Y" ../llvm-project/llvm/utils/lit/lit.py  projects/compiler-rt/test/tsan/IOSSimX86_64Config/ -sv
Invalid device: iPhone Y
Traceback (most recent call last):
  File "/Users/yln/work/llvm-upstream/llvm-project/compiler-rt/test/sanitizer_common/ios_commands/iossim_prepare.py", line 11, in <module>
    subprocess.check_call(boot_cmd)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 190, in check_call
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['xcrun', 'simctl', 'bootstatus', 'iPhone Y', '-b']' returned non-zero exit status 164
Command failed:

lit.py: /Users/yln/work/llvm-upstream/llvm-project/llvm/utils/lit/lit/TestingConfig.py:102: fatal: unable to parse config file '/Users/yln/work/llvm-upstream/llvm-project/compiler-rt/test/lit.common.cfg.py', traceback: Traceback (most recent call last):
  File "/Users/yln/work/llvm-upstream/llvm-project/llvm/utils/lit/lit/TestingConfig.py", line 89, in load_from_path
    exec(compile(data, path, 'exec'), cfg_globals, None)
  File "/Users/yln/work/llvm-upstream/llvm-project/compiler-rt/test/lit.common.cfg.py", line 175, in <module>
    raise e
CalledProcessError: Command '['/Users/yln/work/llvm-upstream/llvm-project/compiler-rt/test/sanitizer_common/ios_commands/iossim_prepare.py', 'iossim', '/Users/yln/work/llvm-upstream/build/./bin/clang']' returned non-zero exit status 1

[delcypher]

compiler-rt/test/sanitizer_common/ios_commands/iossim_prepare.py

23

Ah I missed the -b flag. One issue with this is that we don't teardown the iOS simulator when testing finishes. I guess this mean we'll have a bunch of simulator daemons running in the background on the bot. I don't think there's any great way of fixing this today because I don't think we have a way of adding "clean up" hooks to lit to tell it to execute some custom code when testing finishes.

Maybe leave a TODO and file a radar about this?

[yln]

Add comment about teardown. Remove unused/organize imports.

[yln]

ping

[yln]

Add radar number.

[delcypher]

LGTM

compiler-rt/test/sanitizer_common/ios_commands/iossim_prepare.py

 #!/usr/bin/python
 
-import os, sys, subprocess, json
+import json
+import os
+import subprocess
+
+
+device_id = os.environ.get('SANITIZER_IOSSIM_TEST_DEVICE_IDENTIFIER')
+if not device_id:
+    raise EnvironmentError('Specify SANITIZER_IOSSIM_TEST_DEVICE_IDENTIFIER to select which simulator to use.')
+
+boot_cmd = ['xcrun', 'simctl', 'bootstatus', device_id, '-b']
+subprocess.check_call(boot_cmd)
+# TODO(rdar58118442): we start the simulator here, but we never tear it down
+
 
 print(json.dumps({"env": {}}))