adding callback_manager tests

tests/data_service/test_callback_manager.py

@@ -0,0 +1,56 @@
+import logging
+
+from pytest import CaptureFixture
+
+import pydase
+
+logger = logging.getLogger()
+
+
+def test_DataService_task_callback(capsys: CaptureFixture) -> None:
+    class MyService(pydase.DataService):
+        async def my_task(self) -> None:
+            logger.info("Triggered task.")
+
+        async def my_other_task(self) -> None:
+            logger.info("Triggered other task.")
+
+    service = MyService()
+    service.start_my_task()  # type: ignore
+    service.start_my_other_task()  # type: ignore
+
+    captured = capsys.readouterr()
+    expected_output = sorted(
+        [
+            "MyService.my_task = {}",
+            "MyService.my_other_task = {}",
+        ]
+    )
+    actual_output = sorted(captured.out.strip().split("\n"))  # type: ignore
+    assert expected_output == actual_output
+
+
+def test_DataServiceList_task_callback(capsys: CaptureFixture) -> None:
+    class MySubService(pydase.DataService):
+        async def my_task(self) -> None:
+            logger.info("Triggered task.")
+
+        async def my_other_task(self) -> None:
+            logger.info("Triggered other task.")
+
+    class MyService(pydase.DataService):
+        sub_services_list = [MySubService() for i in range(2)]
+
+    service = MyService()
+    service.sub_services_list[0].start_my_task()  # type: ignore
+    service.sub_services_list[1].start_my_other_task()  # type: ignore
+
+    captured = capsys.readouterr()
+    expected_output = sorted(
+        [
+            "MyService.sub_services_list[0].my_task = {}",
+            "MyService.sub_services_list[1].my_other_task = {}",
+        ]
+    )
+    actual_output = sorted(captured.out.strip().split("\n"))  # type: ignore
+    assert expected_output == actual_output