fix: tickit sim test fixture

Detect start better
tickit does not stop cleanly on python 3.12 so kill process

Author: GDYendell

tests/test_docs_snippets.py

@@ -1,9 +1,8 @@
 import glob
 import runpy
-import signal
 import subprocess
+import time
 from pathlib import Path
-from time import sleep
 
 import pytest
 
@@ -12,21 +11,30 @@
 
 @pytest.fixture(scope="module", autouse=True)
 def sim_temperature_controller():
-    """Subprocess that runs ``tickit all <config_path>``."""
     config_path: str = f"{HERE}/../src/fastcs/demo/simulation/temp_controller.yaml"
-    proc = subprocess.Popen(
+    process = subprocess.Popen(
         ["tickit", "all", config_path],
         stdout=subprocess.PIPE,
         stderr=subprocess.STDOUT,
         text=True,
     )
 
-    sleep(1)
+    TIMEOUT = 10
+    start_time = time.monotonic()
+    while process.stdout is not None:
+        line = process.stdout.readline()
+        if "Temperature controller running" in line:
+            break
+
+        if time.monotonic() - start_time > TIMEOUT:
+            raise TimeoutError("Simulator did not start in time")
+
+        time.sleep(0.1)
 
     yield
 
-    proc.send_signal(signal.SIGINT)
-    print(proc.communicate()[0])
+    process.kill()
+    print(process.communicate()[0])
 
 
 @pytest.mark.parametrize("filename", glob.glob("docs/snippets/*.py", recursive=True))