Return None if return_path=True and .env not found; improve test

src/environs/__init__.py

@@ -454,16 +454,15 @@ def read_env(
         verbose: _BoolType = False,
         override: _BoolType = False,
         return_path: _BoolType = False,
-    ) -> typing.Union[_BoolType, _StrType]:
+    ) -> typing.Union[_BoolType, typing.Optional[_StrType]]:
         """Read a .env file into os.environ.
 
         If .env is not found in the directory from which this method is called,
         the default behavior is to recurse up the directory tree until a .env
         file is found. If you do not wish to recurse up the tree, you may pass
         False as a second positional argument.
         """
-
-        env_path = ""
+        env_path = None
         is_env_loaded = False
         if path is None:
             # By default, start search from the same directory this function is called

tests/test_environs.py

@@ -426,17 +426,14 @@ def test_read_env_return_path_if_env_not_found(self, env, tmp_path):
         # Move .env file to temp location
         env_path = HERE / ".env"
         temp_env = tmp_path / ".env"
-        env_path.rename(temp_env)
-
         try:
+            env_path.rename(temp_env)
             path = env.read_env(return_path=True)
+            assert path is None
         finally:
             # Restore .env file
             if temp_env.exists():
                 temp_env.rename(env_path)
-            assert path == ""
-
-        assert path == ""
 
 
 def always_fail(value):