[WIP] Improving error handling messages for Custom Functions (#1330)

Added separate error handling for ModuleNotFoundError and
FileNotFoundError
	modified:   evadb/utils/generic_utils.py

evadb/utils/generic_utils.py

@@ -75,15 +75,26 @@ def load_function_class_from_file(filepath, classname=None):
         The class instance.
 
     Raises:
-        RuntimeError: If the class name is not found or there is more than one class in the file.
+        ImportError: If the module cannot be loaded.
+        FileNotFoundError: If the file cannot be found.
+        RuntimeError: Any othe type of runtime error.
     """
     try:
         abs_path = Path(filepath).resolve()
         spec = importlib.util.spec_from_file_location(abs_path.stem, abs_path)
         module = importlib.util.module_from_spec(spec)
         spec.loader.exec_module(module)
+    except ImportError as e:
+        # ImportError in the case when we are able to find the file but not able to load the module
+        err_msg = f"ImportError : Couldn't load function from {filepath} : {str(e)}. Not able to load the code provided in the file {abs_path}. Please ensure that the file contains the implementation code for the function."
+        raise ImportError(err_msg)
+    except FileNotFoundError as e:
+        # FileNotFoundError in the case when we are not able to find the file at all at the path.
+        err_msg = f"FileNotFoundError : Couldn't load function from {filepath} : {str(e)}. This might be because the function implementation file does not exist. Please ensure the file exists at {abs_path}"
+        raise FileNotFoundError(err_msg)
     except Exception as e:
-        err_msg = f"Couldn't load function from {filepath} : {str(e)}. This might be due to a missing Python package, or because the function implementation file does not exist, or it is not a valid Python file."
+        # Default exception, we don't know what exactly went wrong so we just output the error message
+        err_msg = f"Couldn't load function from {filepath} : {str(e)}."
         raise RuntimeError(err_msg)
 
     # Try to load the specified class by name
@@ -97,7 +108,7 @@ def load_function_class_from_file(filepath, classname=None):
         if obj.__module__ == module.__name__
     ]
     if len(classes) != 1:
-        raise RuntimeError(
+        raise ImportError(
             f"{filepath} contains {len(classes)} classes, please specify the correct class to load by naming the function with the same name in the CREATE query."
         )
     return classes[0]

test/integration_tests/short/test_generic_utils.py

@@ -14,6 +14,7 @@
 # limitations under the License.
 
 import unittest
+from pathlib import Path
 from test.markers import windows_skip_marker
 
 from evadb.configuration.constants import EvaDB_DATASET_DIR
@@ -50,17 +51,27 @@ def test_should_return_correct_class_for_path_without_classname(self):
         assert vl.__qualname__ == DecordReader.__qualname__
 
     def test_should_raise_on_missing_file(self):
-        with self.assertRaises(RuntimeError):
+        # Asserting on the error message, but that's brittle
+        with self.assertRaises(FileNotFoundError):
             load_function_class_from_file("evadb/readers/opencv_reader_abdfdsfds.py")
 
+    def test_should_raise_on_empty_file(self):
+        # Asserting on the error message, but that's brittle
+        Path("/tmp/empty_file.py").touch()
+        with self.assertRaises(ImportError):
+            load_function_class_from_file("/tmp/empty_file.py")
+
+        # Cleanup
+        Path("/tmp/empty_file.py").unlink()
+
     def test_should_raise_if_class_does_not_exists(self):
-        with self.assertRaises(RuntimeError):
+        with self.assertRaises(ImportError):
             # evadb/utils/s3_utils.py has no class in it
             # if this test fails due to change in s3_utils.py, change the file to something else
             load_function_class_from_file("evadb/utils/s3_utils.py")
 
     def test_should_raise_if_multiple_classes_exist_and_no_class_mentioned(self):
-        with self.assertRaises(RuntimeError):
+        with self.assertRaises(ImportError):
             # evadb/utils/generic_utils.py has multiple classes in it
             # if this test fails due to change in generic_utils.py, change the file to something else
             load_function_class_from_file("evadb/utils/generic_utils.py")