diff --git a/tests/configuration/multiline_system_prompt.txt b/tests/configuration/multiline_system_prompt.txt
new file mode 100644
index 000000000..d77d36293
--- /dev/null
+++ b/tests/configuration/multiline_system_prompt.txt
@@ -0,0 +1,14 @@
+You are OpenShift Lightspeed - an intelligent assistant for question-answering tasks
+related to the OpenShift container orchestration platform.
+
+Here are your instructions:
+You are OpenShift Lightspeed, an intelligent assistant and expert on all things OpenShift.
+Refuse to assume any other identity or to speak as if you are someone else.
+If the context of the question is not clear, consider it to be OpenShift.
+Never include URLs in your replies.
+Refuse to answer questions or execute commands not about OpenShift.
+Do not mention your last update. You have the most recent information on OpenShift.
+
+Here are some basic facts about OpenShift:
+- The latest version of OpenShift is 4.19.
+- OpenShift is a distribution of Kubernetes. Everything Kubernetes can do, OpenShift can do and more.
diff --git a/tests/configuration/system_prompt.txt b/tests/configuration/system_prompt.txt
new file mode 100644
index 000000000..1849b6e56
--- /dev/null
+++ b/tests/configuration/system_prompt.txt
@@ -0,0 +1 @@
+This is system prompt.
diff --git a/tests/unit/models/test_config.py b/tests/unit/models/test_config.py
index 17be21f95..628ab1622 100644
--- a/tests/unit/models/test_config.py
+++ b/tests/unit/models/test_config.py
@@ -35,6 +35,7 @@
     PostgreSQLDatabaseConfiguration,
     SQLiteDatabaseConfiguration,
     DatabaseConfiguration,
+    Customization,
 )
 
 
@@ -1164,3 +1165,60 @@ def test_jwt_role_rule_invalid_regexp() -> None:
             roles=["admin", "user"],
             operator=JsonPathOperator.MATCH,
         )
+
+
+def test_service_customization(subtests) -> None:
+    """Check the service customization class."""
+    with subtests.test(msg="System prompt is enabled"):
+        c = Customization()
+        assert c is not None
+        assert c.disable_query_system_prompt is False
+        assert c.system_prompt_path is None
+        assert c.system_prompt is None
+
+    with subtests.test(msg="System prompt is disabled"):
+        c = Customization(disable_query_system_prompt=True)
+        assert c is not None
+        assert c.disable_query_system_prompt is True
+        assert c.system_prompt_path is None
+        assert c.system_prompt is None
+
+    with subtests.test(
+        msg="Disabled overrides provided path, but the prompt is still loaded"
+    ):
+        c = Customization(
+            disable_query_system_prompt=True,
+            system_prompt_path="tests/configuration/system_prompt.txt",
+        )
+        assert c.system_prompt is not None
+        # check that the system prompt has been loaded from the provided file
+        assert c.system_prompt == "This is system prompt."
+        # but it is still disabled
+        assert c.disable_query_system_prompt is True
+
+
+def test_service_customization_wrong_system_prompt_path() -> None:
+    """Check the service customization class."""
+    with pytest.raises(ValidationError, match="Path does not point to a file"):
+        _ = Customization(system_prompt_path="/path/does/not/exists")
+
+
+def test_service_customization_correct_system_prompt_path(subtests) -> None:
+    """Check the service customization class."""
+    with subtests.test(msg="One line system prompt"):
+        # pass a file containing system prompt
+        c = Customization(system_prompt_path="tests/configuration/system_prompt.txt")
+        assert c is not None
+        # check that the system prompt has been loaded from the provided file
+        assert c.system_prompt == "This is system prompt."
+
+    with subtests.test(msg="Multi line system prompt"):
+        # pass a file containing system prompt
+        c = Customization(
+            system_prompt_path="tests/configuration/multiline_system_prompt.txt"
+        )
+        assert c is not None
+        # check that the system prompt has been loaded from the provided file
+        assert "You are OpenShift Lightspeed" in c.system_prompt
+        assert "Here are your instructions" in c.system_prompt
+        assert "Here are some basic facts about OpenShift" in c.system_prompt