Add first unit tests for process_pool_worker (#3766)

The only change of note is to move the `ArgumentParser` to a function to
enable writing unit tests for it.

# Changed Behaviour

No user-functional change.

## Type of change

- Code maintenance/cleanup

Author: khk-globus

parsl/executors/high_throughput/process_worker_pool.py

@@ -809,63 +809,132 @@ def start_file_logger(filename, rank, name='parsl', level=logging.DEBUG, format_
     return logger
 
 
-if __name__ == "__main__":
-
-    parser = argparse.ArgumentParser()
-    parser.add_argument("-d", "--debug", action='store_true',
-                        help="Enable logging at DEBUG level")
-    parser.add_argument("-a", "--addresses", default='',
-                        help="Comma separated list of addresses at which the interchange could be reached")
-    parser.add_argument("--cert_dir", required=True,
-                        help="Path to certificate directory.")
-    parser.add_argument("-l", "--logdir", default="process_worker_pool_logs",
-                        help="Process worker pool log directory")
-    parser.add_argument("-u", "--uid", default=str(uuid.uuid4()).split('-')[-1],
-                        help="Unique identifier string for Manager")
-    parser.add_argument("-b", "--block_id", default=None,
-                        help="Block identifier for Manager")
-    parser.add_argument("-c", "--cores_per_worker", default="1.0",
-                        help="Number of cores assigned to each worker process. Default=1.0")
-    parser.add_argument("-m", "--mem_per_worker", default=0,
-                        help="GB of memory assigned to each worker process. Default=0, no assignment")
-    parser.add_argument("-t", "--task_port", required=True,
-                        help="REQUIRED: Task port for receiving tasks from the interchange")
-    parser.add_argument("--max_workers_per_node", default=float('inf'),
-                        help="Caps the maximum workers that can be launched, default:infinity")
-    parser.add_argument("-p", "--prefetch_capacity", default=0,
-                        help="Number of tasks that can be prefetched to the manager. Default is 0.")
-    parser.add_argument("--hb_period", default=30,
-                        help="Heartbeat period in seconds. Uses manager default unless set")
-    parser.add_argument("--hb_threshold", default=120,
-                        help="Heartbeat threshold in seconds. Uses manager default unless set")
-    parser.add_argument("--drain_period", default=None,
-                        help="Drain this pool after specified number of seconds. By default, does not drain.")
-    parser.add_argument("--address_probe_timeout", default=30,
-                        help="Timeout to probe for viable address to interchange. Default: 30s")
-    parser.add_argument("--poll", default=10,
-                        help="Poll period used in milliseconds")
-    parser.add_argument("-r", "--result_port", required=True,
-                        help="REQUIRED: Result port for posting results to the interchange")
+def get_arg_parser() -> argparse.ArgumentParser:
 
     def strategyorlist(s: str):
-        allowed_strategies = ["none", "block", "alternating", "block-reverse"]
+        s = s.lower()
+        allowed_strategies = ("none", "block", "alternating", "block-reverse")
         if s in allowed_strategies:
             return s
         elif s[0:4] == "list":
             return s
-        else:
-            raise argparse.ArgumentTypeError("cpu-affinity must be one of {} or a list format".format(allowed_strategies))
-
-    parser.add_argument("--cpu-affinity", type=strategyorlist,
-                        required=True,
-                        help="Whether/how workers should control CPU affinity.")
-    parser.add_argument("--available-accelerators", type=str, nargs="*",
-                        help="Names of available accelerators, if not given assumed to be zero accelerators available", default=[])
-    parser.add_argument("--enable_mpi_mode", action='store_true',
-                        help="Enable MPI mode")
-    parser.add_argument("--mpi-launcher", type=str, choices=VALID_LAUNCHERS,
-                        help="MPI launcher to use iff enable_mpi_mode=true")
+        err_msg = f"cpu-affinity must be one of {allowed_strategies} or a list format"
+        raise argparse.ArgumentTypeError(err_msg)
 
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        "-d", "--debug", action='store_true', help="Enable logging at DEBUG level",
+    )
+    parser.add_argument(
+        "-a",
+        "--addresses",
+        default='',
+        help="Comma separated list of addresses at which the interchange could be reached",
+    )
+    parser.add_argument(
+        "--cert_dir", required=True, help="Path to certificate directory."
+    )
+    parser.add_argument(
+        "-l",
+        "--logdir",
+        default="process_worker_pool_logs",
+        help="Process worker pool log directory",
+    )
+    parser.add_argument(
+        "-u",
+        "--uid",
+        default=str(uuid.uuid4()).split('-')[-1],
+        help="Unique identifier string for Manager",
+    )
+    parser.add_argument(
+        "-b", "--block_id", default=None, help="Block identifier for Manager"
+    )
+    parser.add_argument(
+        "-c",
+        "--cores_per_worker",
+        default="1.0",
+        help="Number of cores assigned to each worker process. Default=1.0",
+    )
+    parser.add_argument(
+        "-m",
+        "--mem_per_worker",
+        default=0,
+        help="GB of memory assigned to each worker process. Default=0, no assignment",
+    )
+    parser.add_argument(
+        "-t",
+        "--task_port",
+        required=True,
+        help="Task port for receiving tasks from the interchange",
+    )
+    parser.add_argument(
+        "--max_workers_per_node",
+        default=float('inf'),
+        help="Caps the maximum workers that can be launched, default:infinity",
+    )
+    parser.add_argument(
+        "-p",
+        "--prefetch_capacity",
+        default=0,
+        help="Number of tasks that can be prefetched to the manager. Default is 0.",
+    )
+    parser.add_argument(
+        "--hb_period",
+        default=30,
+        help="Heartbeat period in seconds. Uses manager default unless set",
+    )
+    parser.add_argument(
+        "--hb_threshold",
+        default=120,
+        help="Heartbeat threshold in seconds. Uses manager default unless set",
+    )
+    parser.add_argument(
+        "--drain_period",
+        default=None,
+        help="Drain this pool after specified number of seconds. By default, does not drain.",
+    )
+    parser.add_argument(
+        "--address_probe_timeout",
+        default=30,
+        help="Timeout to probe for viable address to interchange. Default: 30s",
+    )
+    parser.add_argument(
+        "--poll", default=10, help="Poll period used in milliseconds"
+    )
+    parser.add_argument(
+        "-r",
+        "--result_port",
+        required=True,
+        help="Result port for posting results to the interchange",
+    )
+    parser.add_argument(
+        "--cpu-affinity",
+        type=strategyorlist,
+        required=True,
+        help="Whether/how workers should control CPU affinity.",
+    )
+    parser.add_argument(
+        "--available-accelerators",
+        type=str,
+        nargs="*",
+        default=[],
+        help="Names of available accelerators, if not given assumed to be zero accelerators available",
+    )
+    parser.add_argument(
+        "--enable_mpi_mode", action='store_true', help="Enable MPI mode"
+    )
+    parser.add_argument(
+        "--mpi-launcher",
+        type=str,
+        choices=VALID_LAUNCHERS,
+        help="MPI launcher to use iff enable_mpi_mode=true",
+    )
+
+    return parser
+
+
+if __name__ == "__main__":
+    parser = get_arg_parser()
     args = parser.parse_args()
 
     os.makedirs(os.path.join(args.logdir, "block-{}".format(args.block_id), args.uid), exist_ok=True)

parsl/tests/unit/executors/high_throughput/__init__.py

@@ -0,0 +1,74 @@
+import sys
+from argparse import ArgumentError
+
+import pytest
+
+from parsl.executors.high_throughput import process_worker_pool
+
+if sys.version_info < (3, 12):
+    # exit_on_error bug; see https://github.com/python/cpython/issues/121018
+    # "argparse.ArgumentParser.parses_args does not honor exit_on_error=False when
+    #  given unrecognized arguments"
+    pytest.skip(allow_module_level=True, reason="exit_on_error argparse bug")
+
+# due to above pytest.skip, mypy on < Py312 thinks this is unreachable.  :facepalm:
+_known_required = (  # type: ignore[unreachable, unused-ignore]
+    "--cert_dir",
+    "--cpu-affinity",
+    "--result_port",
+    "--task_port",
+)
+
+
+@pytest.mark.local
+def test_arg_parser_exits_on_error():
+    p = process_worker_pool.get_arg_parser()
+    assert p.exit_on_error
+
+
+@pytest.mark.local
+def test_arg_parser_known_required():
+    p = process_worker_pool.get_arg_parser()
+    reqd = [a for a in p._actions if a.required]
+    for a in reqd:
+        assert a.option_strings[-1] in _known_required, "Update _known_required?"
+
+
+@pytest.mark.local
+@pytest.mark.parametrize("req", _known_required)
+def test_arg_parser_required(req):
+    p = process_worker_pool.get_arg_parser()
+    p.exit_on_error = False
+    with pytest.raises(ArgumentError) as pyt_exc:
+        p.parse_args([])
+
+    e_msg = pyt_exc.value.args[1]
+    assert req in e_msg
+
+
+@pytest.mark.local
+@pytest.mark.parametrize("valid,val", (
+        (True, "NoNe"),
+        (True, "none"),
+        (True, "block"),
+        (True, "alternating"),
+        (True, "block-reverse"),
+        (True, "list"),
+        (False, "asdf"),
+        (False, ""),
+))
+def test_arg_parser_validates_cpu_affinity(valid, val):
+    reqd_args = []
+    reqd_args.extend(("--cert_dir", "/some/path"))
+    reqd_args.extend(("--result_port", "123"))
+    reqd_args.extend(("--task_port", "123"))
+    reqd_args.extend(("--cpu-affinity", val))
+
+    p = process_worker_pool.get_arg_parser()
+    p.exit_on_error = False
+    if valid:
+        p.parse_args(reqd_args)
+    else:
+        with pytest.raises(ArgumentError) as pyt_exc:
+            p.parse_args(reqd_args)
+        assert "must be one of" in pyt_exc.value.args[1]