feat: return False when we do not discover any environment variables (#388)

* Fix docstring for load_dotenv

The docstring for load_dotenv was missing a word, rendering it confusing.
This commits modifies it for clarity.

* Return False when we do not discover any environment variables

This modifies Dotenv.set_as_environment_variables to return False
if we have not discovered any environment variables via either
`dotenv_path` or `stream`.

The return value gets passed through to `load_dotenv`, so this can be
used to determine if `dotenv.load_dotenv` was able to set anything.

Closes #321

Co-authored-by: Saurabh Kumar <theskumar@users.noreply.github.com>

Author: larsks

src/dotenv/main.py

@@ -87,6 +87,9 @@ def set_as_environment_variables(self) -> bool:
         """
         Load the current dotenv as system environment variable.
         """
+        if not self.dict():
+            return False
+
         for k, v in self.dict().items():
             if k in os.environ and not self.override:
                 continue
@@ -324,6 +327,8 @@ def load_dotenv(
         override: Whether to override the system environment variables with the variables
             from the `.env` file.
         encoding: Encoding to be used to read the file.
+    Returns:
+        Bool: True if atleast one environment variable is set elese False
 
     If both `dotenv_path` and `stream` are `None`, `find_dotenv()` is used to find the
     .env file.

tests/test_main.py

@@ -259,8 +259,9 @@ def test_load_dotenv_no_file_verbose():
     logger = logging.getLogger("dotenv.main")
 
     with mock.patch.object(logger, "info") as mock_info:
-        dotenv.load_dotenv('.does_not_exist', verbose=True)
+        result = dotenv.load_dotenv('.does_not_exist', verbose=True)
 
+    assert result is False
     mock_info.assert_called_once_with("Python-dotenv could not find configuration file %s.", ".does_not_exist")