Raise FileNotFoundError when the env_file parameter on Config is not valid (#2422)

* raise error on missing env file

* format

---------

Co-authored-by: Marcelo Trylesinski <[email protected]>

Author: mathause

starlette/config.py

@@ -58,7 +58,9 @@ def __init__(
         self.environ = environ
         self.env_prefix = env_prefix
         self.file_values: typing.Dict[str, str] = {}
-        if env_file is not None and os.path.isfile(env_file):
+        if env_file is not None:
+            if not os.path.isfile(env_file):
+                raise FileNotFoundError(f"Config file '{env_file}' not found.")
             self.file_values = self._read_file(env_file)
 
     @typing.overload

tests/test_config.py

@@ -104,6 +104,13 @@ def cast_to_int(v) -> int:
         config.get("BOOL_AS_INT", cast=bool)
 
 
+def test_missing_env_file_raises(tmpdir):
+    path = os.path.join(tmpdir, ".env")
+
+    with pytest.raises(FileNotFoundError, match=f"Config file '{path}' not found."):
+        Config(path)
+
+
 def test_environ():
     environ = Environ()