tests: net: sockets: tls_configurations: Use fixture for openssl

Currently, creating and killing openssl process was part of the test. In
result, if the test case failed for whatever reason, the openssl process
would remain open, causing disruptions in consecutive test executions.

Fix that by defining openssl server instance as a pytest fixture. That
way, openssl process will be terminated regardless of the test
result.

Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>

tests/net/socket/tls_configurations/pytest/test_app_vs_openssl.py

@@ -7,6 +7,8 @@ import os
 import subprocess
 from twister_harness import DeviceAdapter
 
+import pytest
+
 logger = logging.getLogger(__name__)
 
 def get_arguments_from_server_type(server_type, port):
@@ -51,7 +53,8 @@ def get_arguments_from_server_type(server_type, port):
                  "-accept", "{}".format(port)])
     return args
 
-def start_server(server_type, port):
+@pytest.fixture()
+def openssl_server(server_type, port):
     logger.info("Server type: " + server_type)
     args = get_arguments_from_server_type(server_type, port)
     logger.info("Launch command:")
@@ -67,14 +70,12 @@ def start_server(server_type, port):
     except subprocess.TimeoutExpired:
         logger.info("Server is up")
 
-    return openssl
+    yield
 
-def test_app_vs_openssl(dut: DeviceAdapter, server_type, port):
-    server = start_server(server_type, port)
+    logger.info("Kill server")
+    openssl.kill()
 
+def test_app_vs_openssl(dut: DeviceAdapter, openssl_server):
     logger.info("Launch Zephyr application")
     dut.launch()
     dut.readlines_until("Test PASSED", timeout=3.0)
-
-    logger.info("Kill server")
-    server.kill()