Refactor mod_import to use importlib

Switch from the deprecated imp to importlib. Also add tests and
clean up logic flow. This should be quite a bit faster than the
old implementation as well.

evennia/utils/tests/test_utils.py

@@ -5,6 +5,8 @@ TODO: Not nearly all utilities are covered yet.
 
 """
 
+import os.path
+
 import mock
 from django.test import TestCase
 from datetime import datetime
@@ -203,3 +205,27 @@ class TestDateTimeFormat(TestCase):
         self.assertEqual(utils.datetime_format(dtobj), "19:54")
         dtobj = datetime(2019, 8, 28, 21, 32)
         self.assertEqual(utils.datetime_format(dtobj), "21:32:00")
+
+
+class TestImportFunctions(TestCase):
+    def _t_dir_file(self, filename):
+        testdir = os.path.dirname(os.path.abspath(__file__))
+        return os.path.join(testdir, filename)
+
+    def test_mod_import(self):
+        loaded_mod = utils.mod_import('evennia.utils.ansi')
+        self.assertIsNotNone(loaded_mod)
+
+    def test_mod_import_invalid(self):
+        loaded_mod = utils.mod_import('evennia.utils.invalid_module')
+        self.assertIsNone(loaded_mod)
+
+    def test_mod_import_from_path(self):
+        test_path = self._t_dir_file('test_eveditor.py')
+        loaded_mod = utils.mod_import_from_path(test_path)
+        self.assertIsNotNone(loaded_mod)
+
+    def test_mod_import_from_path_invalid(self):
+        test_path = self._t_dir_file('invalid_filename.py')
+        loaded_mod = utils.mod_import_from_path(test_path)
+        self.assertIsNone(loaded_mod)

evennia/utils/utils.py

@@ -9,7 +9,6 @@ be of use when designing your own game.
 import os
 import gc
 import sys
-import imp
 import types
 import math
 import re
@@ -17,6 +16,7 @@ import textwrap
 import random
 import inspect
 import traceback
+import importlib.machinery
 from twisted.internet.task import deferLater
 from twisted.internet.defer import returnValue  # noqa - used as import target
 from os.path import join as osjoin
@@ -1166,6 +1166,30 @@ def has_parent(basepath, obj):
         return False
 
 
+def mod_import_from_path(path):
+    """
+    Load a Python module at the specified path.
+
+    Args:
+        path (str): An absolute path to a Python module to load.
+
+    Returns:
+        (module or None): An imported module if the path was a valid
+        Python module. Returns `None` if the import failed.
+
+    """
+    if not os.path.isabs(path):
+        path = os.path.abspath(path)
+    dirpath, filename = path.rsplit(os.path.sep, 1)
+    modname = filename.rstrip('.py')
+
+    try:
+        return importlib.machinery.SourceFileLoader(modname, path).load_module()
+    except OSError:
+        logger.log_trace(f"Could not find module '{modname}' ({modname}.py) at path '{dirpath}'")
+        return None
+
+
 def mod_import(module):
     """
     A generic Python module loader.
@@ -1173,52 +1197,28 @@ def mod_import(module):
     Args:
         module (str, module): This can be either a Python path
             (dot-notation like `evennia.objects.models`), an absolute path
-            (e.g. `/home/eve/evennia/evennia/objects.models.py`) or an
+            (e.g. `/home/eve/evennia/evennia/objects/models.py`) or an
             already imported module object (e.g. `models`)
     Returns:
-        module (module or None): An imported module. If the input argument was
+        (module or None): An imported module. If the input argument was
         already a module, this is returned as-is, otherwise the path is
         parsed and imported. Returns `None` and logs error if import failed.
 
     """
-
     if not module:
         return None
 
     if isinstance(module, types.ModuleType):
         # if this is already a module, we are done
-        mod = module
-    else:
-        # first try to import as a python path
-        try:
-            mod = __import__(module, fromlist=["None"])
-        except ImportError as ex:
-            # check just where the ImportError happened (it could have been
-            # an erroneous import inside the module as well). This is the
-            # trivial way to do it ...
-            if not str(ex).startswith("No module named "):
-                raise
+        return module
 
-            # error in this module. Try absolute path import instead
+    if module.endswith('.py') and os.path.exists(module):
+        return mod_import_from_path(module)
 
-            if not os.path.isabs(module):
-                module = os.path.abspath(module)
-            path, filename = module.rsplit(os.path.sep, 1)
-            modname = re.sub(r"\.py$", "", filename)
-
-            try:
-                result = imp.find_module(modname, [path])
-            except ImportError:
-                logger.log_trace("Could not find module '%s' (%s.py) at path '%s'" % (modname, modname, path))
-                return None
-            try:
-                mod = imp.load_module(modname, *result)
-            except ImportError:
-                logger.log_trace("Could not find or import module %s at path '%s'" % (modname, path))
-                mod = None
-            # we have to close the file handle manually
-            result[0].close()
-    return mod
+    try:
+        return import_module(module)
+    except ImportError:
+        return None
 
 
 def all_from_module(module):