diff --git a/tests/conftest.py b/tests/conftest.py
index 7dd7149fe..06a693366 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -67,6 +67,7 @@ def slurm_system(tmp_path: Path) -> SlurmSystem:
     )
     system.scheduler = "slurm"
     system.monitor_interval = 0
+    system.supports_gpu_directives_cache = True
     return system
 
 
diff --git a/tests/systems/slurm/test_system.py b/tests/systems/slurm/test_system.py
index 0ad79b61f..df2cc5d9f 100644
--- a/tests/systems/slurm/test_system.py
+++ b/tests/systems/slurm/test_system.py
@@ -16,7 +16,6 @@
 
 import re
 from pathlib import Path
-from typing import Dict, List
 from unittest.mock import Mock, patch
 
 import pytest
@@ -145,14 +144,28 @@ def grouped_nodes() -> dict[SlurmNodeState, list[SlurmNode]]:
     return grouped_nodes
 
 
-def test_get_available_nodes_exceeding_limit_no_callstack(
-    slurm_system: SlurmSystem, grouped_nodes: Dict[SlurmNodeState, List[SlurmNode]], caplog
-):
+def test_get_available_nodes_exceeding_limit_no_callstack(slurm_system: SlurmSystem, caplog):
     group_name = "group1"
     partition_name = "main"
     num_nodes = 5
+    empty_grouped_nodes = {
+        SlurmNodeState.IDLE: [],
+        SlurmNodeState.COMPLETING: [],
+        SlurmNodeState.ALLOCATED: [],
+    }
+
+    mod_path = "cloudai.systems.slurm.slurm_system.SlurmSystem"
+    with (
+        patch(f"{mod_path}.update", return_value=None) as mock_update,
+        patch(f"{mod_path}.group_nodes_by_state", return_value=empty_grouped_nodes) as mock_group_nodes_by_state,
+    ):
+        slurm_system.get_available_nodes_from_group(partition_name, group_name, num_nodes)
 
-    slurm_system.get_available_nodes_from_group(partition_name, group_name, num_nodes)
+    mock_update.assert_called_once()
+    mock_group_nodes_by_state.assert_called_once()
+    args, kwargs = mock_group_nodes_by_state.call_args
+    assert args == (partition_name, group_name)
+    assert kwargs in ({}, {"exclude_nodes": None})
 
     log_message = "CloudAI is requesting 5 nodes from the group 'group1', but only 0 nodes are available."
     assert log_message in caplog.text
@@ -513,10 +526,27 @@ def test_per_step_isolation(self, mock_get_nodes: Mock, slurm_system: SlurmSyste
 def test_supports_gpu_directives(
     mock_fetch_command_output, scontrol_output: str, expected_support: bool, slurm_system: SlurmSystem
 ):
+    slurm_system.supports_gpu_directives_cache = None
     mock_fetch_command_output.return_value = (scontrol_output, "")
     assert slurm_system.supports_gpu_directives == expected_support
 
 
+@patch("cloudai.systems.slurm.slurm_system.SlurmSystem.fetch_command_output")
+def test_supports_gpu_directives_defaults_to_true_on_probe_error(
+    mock_fetch_command_output, slurm_system: SlurmSystem, caplog: pytest.LogCaptureFixture
+):
+    slurm_system.supports_gpu_directives_cache = None
+    stderr = "scontrol failed"
+    mock_fetch_command_output.return_value = ("", stderr)
+
+    with caplog.at_level("WARNING"):
+        assert slurm_system.supports_gpu_directives is True
+
+    assert slurm_system.supports_gpu_directives_cache is True
+    assert f"Error checking GPU support: {stderr}" in caplog.text
+    mock_fetch_command_output.assert_called_once_with("scontrol show config")
+
+
 @pytest.mark.parametrize(
     "cache_value",
     [True, False],