Make numpy import lazy in prometheus_connect.py

- Remove numpy import from module level in prometheus_connect.py
- Add lazy import of numpy inside get_metric_aggregation method
- Add tests to verify PrometheusConnect can be imported without loading pandas/matplotlib/numpy
- All mocked network tests pass successfully

Co-authored-by: 4n4nd <22333506+4n4nd@users.noreply.github.com>

Author: Copilot

prometheus_api_client/prometheus_connect.py

@@ -4,7 +4,6 @@
 import os
 import json
 import logging
-import numpy
 from datetime import datetime, timedelta
 import requests
 from requests.adapters import HTTPAdapter
@@ -569,6 +568,8 @@ def get_metric_aggregation(
                 'max': 6.009373
              }
         """
+        import numpy
+        
         if not isinstance(operations, list):
             raise TypeError("Operations can be only of type list")
         if len(operations) == 0:

tests/test_lazy_imports.py

@@ -0,0 +1,100 @@
+"""Test lazy imports to ensure pandas/matplotlib are not loaded unnecessarily."""
+import unittest
+import sys
+import importlib
+
+
+class TestLazyImports(unittest.TestCase):
+    """Test that PrometheusConnect can be imported without loading heavy dependencies."""
+
+    def test_prometheus_connect_import_without_pandas_matplotlib_numpy(self):
+        """Test that importing PrometheusConnect doesn't load pandas, matplotlib, or numpy."""
+        # Remove any previously loaded prometheus_api_client modules
+        modules_to_remove = [
+            key for key in sys.modules.keys()
+            if key.startswith('prometheus_api_client')
+        ]
+        for module in modules_to_remove:
+            del sys.modules[module]
+        
+        # Also remove numpy, pandas, matplotlib if they were loaded
+        for heavy_module in ['numpy', 'pandas', 'matplotlib']:
+            modules_to_remove = [
+                key for key in sys.modules.keys()
+                if key == heavy_module or key.startswith(heavy_module + '.')
+            ]
+            for module in modules_to_remove:
+                del sys.modules[module]
+        
+        # Import PrometheusConnect
+        from prometheus_api_client import PrometheusConnect
+        
+        # Check that pandas, matplotlib, and numpy are not loaded
+        loaded_modules = sys.modules.keys()
+        pandas_loaded = any('pandas' in m for m in loaded_modules)
+        matplotlib_loaded = any('matplotlib' in m for m in loaded_modules)
+        numpy_loaded = any('numpy' in m for m in loaded_modules)
+        
+        self.assertFalse(pandas_loaded, "pandas should not be loaded when importing PrometheusConnect")
+        self.assertFalse(matplotlib_loaded, "matplotlib should not be loaded when importing PrometheusConnect")
+        self.assertFalse(numpy_loaded, "numpy should not be loaded when importing PrometheusConnect")
+        
+    def test_prometheus_connect_instantiation_without_numpy(self):
+        """Test that PrometheusConnect can be instantiated without loading numpy."""
+        # Remove any previously loaded prometheus_api_client modules
+        modules_to_remove = [
+            key for key in sys.modules.keys()
+            if key.startswith('prometheus_api_client')
+        ]
+        for module in modules_to_remove:
+            del sys.modules[module]
+        
+        # Also remove numpy if it was loaded
+        modules_to_remove = [
+            key for key in sys.modules.keys()
+            if key == 'numpy' or key.startswith('numpy.')
+        ]
+        for module in modules_to_remove:
+            del sys.modules[module]
+        
+        # Import and instantiate PrometheusConnect
+        from prometheus_api_client import PrometheusConnect
+        pc = PrometheusConnect(url='http://test.local:9090')
+        
+        # Check that numpy is still not loaded after instantiation
+        loaded_modules = sys.modules.keys()
+        numpy_loaded = any('numpy' in m for m in loaded_modules)
+        
+        self.assertFalse(numpy_loaded, "numpy should not be loaded when instantiating PrometheusConnect")
+        self.assertIsNotNone(pc, "PrometheusConnect should be instantiated successfully")
+
+    def test_metric_import_loads_pandas(self):
+        """Test that importing Metric does load pandas (expected behavior)."""
+        # Remove any previously loaded prometheus_api_client modules
+        modules_to_remove = [
+            key for key in sys.modules.keys()
+            if key.startswith('prometheus_api_client')
+        ]
+        for module in modules_to_remove:
+            del sys.modules[module]
+        
+        # Also remove pandas if it was loaded
+        modules_to_remove = [
+            key for key in sys.modules.keys()
+            if key == 'pandas' or key.startswith('pandas.')
+        ]
+        for module in modules_to_remove:
+            del sys.modules[module]
+        
+        # Import Metric
+        from prometheus_api_client import Metric
+        
+        # Check that pandas is loaded (this is expected for Metric)
+        loaded_modules = sys.modules.keys()
+        pandas_loaded = any('pandas' in m for m in loaded_modules)
+        
+        self.assertTrue(pandas_loaded, "pandas should be loaded when importing Metric")
+
+
+if __name__ == '__main__':
+    unittest.main()