test: Enhance test coverage and fix CI issues

- Add comprehensive unit tests for core functions
- Mock user input to prevent test failures
- Fix unused variable warnings in tests
- Ensure all CI checks pass locally

Author: KKamJi98

tests/test_kubernetes_monitoring.py

@@ -1,9 +1,73 @@
 import os
 import sys
+from unittest.mock import MagicMock, patch
 
 sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), os.pardir)))
 import kubernetes_monitoring
 
 
 def test_main_function_exists():
+    """Test that main function exists and is callable"""
     assert callable(kubernetes_monitoring.main)
+
+
+def test_node_group_label_constant():
+    """Test that NODE_GROUP_LABEL constant is defined"""
+    assert hasattr(kubernetes_monitoring, "NODE_GROUP_LABEL")
+    assert isinstance(kubernetes_monitoring.NODE_GROUP_LABEL, str)
+
+
+@patch("kubernetes_monitoring.config")
+def test_load_kube_config_success(mock_config):
+    """Test successful kube config loading"""
+    mock_config.load_kube_config.return_value = None
+
+    # Should not raise an exception
+    kubernetes_monitoring.load_kube_config()
+    mock_config.load_kube_config.assert_called_once()
+
+
+@patch("kubernetes_monitoring.config")
+@patch("sys.exit")
+def test_load_kube_config_failure(mock_exit, mock_config):
+    """Test kube config loading failure"""
+    mock_config.load_kube_config.side_effect = Exception("Config error")
+
+    kubernetes_monitoring.load_kube_config()
+    mock_exit.assert_called_once_with(1)
+
+
+@patch("kubernetes_monitoring.Prompt.ask")
+@patch("kubernetes_monitoring.client")
+@patch("kubernetes_monitoring.load_kube_config")
+def test_choose_namespace_success(mock_load_config, mock_client, mock_prompt):
+    """Test successful namespace selection"""
+    # Mock the namespace list
+    mock_ns = MagicMock()
+    mock_ns.metadata.name = "test-namespace"
+
+    mock_ns_list = MagicMock()
+    mock_ns_list.items = [mock_ns]
+
+    mock_v1 = MagicMock()
+    mock_v1.list_namespace.return_value = mock_ns_list
+    mock_client.CoreV1Api.return_value = mock_v1
+
+    # Mock user input (empty string for default/all namespaces)
+    mock_prompt.return_value = ""
+
+    # This should not raise an exception
+    kubernetes_monitoring.choose_namespace()
+    mock_load_config.assert_called_once()
+
+
+@patch("kubernetes_monitoring.client")
+@patch("kubernetes_monitoring.load_kube_config")
+def test_choose_namespace_failure(mock_load_config, mock_client):
+    """Test namespace selection failure"""
+    mock_v1 = MagicMock()
+    mock_v1.list_namespace.side_effect = Exception("API error")
+    mock_client.CoreV1Api.return_value = mock_v1
+
+    kubernetes_monitoring.choose_namespace()
+    assert mock_load_config.called