From d478d92299d4025067e17beb4f5ec565f0b3033e Mon Sep 17 00:00:00 2001
From: Ruairidh MacLeod <ruairidh@rkm.dev>
Date: Fri, 24 Dec 2021 01:35:27 +0000
Subject: [PATCH 1/2] add failing test for missing config file

---
 tests/integration/test_main.py    | 18 ++++++++++++++++++
 tests/unit/test_options_config.py |  6 ++++++
 2 files changed, 24 insertions(+)

diff --git a/tests/integration/test_main.py b/tests/integration/test_main.py
index b351e9d..90877d3 100644
--- a/tests/integration/test_main.py
+++ b/tests/integration/test_main.py
@@ -386,3 +386,21 @@ def test_early_keyboard_interrupt_does_not_crash(capsys):
     out, err = capsys.readouterr()
     assert out == "... stopped\n"
     assert err == ""
+
+
+def test_config_file_not_found(tmpdir, capsys):
+    """Ensure that an explicitly specified config file which is not found is an
+    error"""
+
+    expected = """\
+There was a critical error during execution of Flake8:
+The specified config file does not exist
+"""
+
+    with tmpdir.as_cwd():
+        tmpdir.join("t.py").write("print('hello hello world')\n")
+        assert cli.main(["--config", "missing.cfg", "t.py"]) == 1
+
+    out, err = capsys.readouterr()
+    assert out == expected
+    assert err == ""
diff --git a/tests/unit/test_options_config.py b/tests/unit/test_options_config.py
index b288de0..c5d1476 100644
--- a/tests/unit/test_options_config.py
+++ b/tests/unit/test_options_config.py
@@ -2,6 +2,7 @@ import configparser
 
 import pytest
 
+from flake8 import exceptions
 from flake8.main.options import register_default_options
 from flake8.options import config
 from flake8.options.manager import OptionManager
@@ -164,3 +165,8 @@ def test_parse_config_ignores_unknowns(tmp_path, opt_manager, caplog):
             'Option "wat" is not registered. Ignoring.',
         )
     ]
+
+
+def test_load_config_missing_file_raises_exception(capsys):
+    with pytest.raises(exceptions.ExecutionError):
+        config.load_config("foo.cfg", [])

From d948169292388116c45febad470162ba5652dd60 Mon Sep 17 00:00:00 2001
From: Ruairidh MacLeod <ruairidh@rkm.dev>
Date: Fri, 24 Dec 2021 01:36:41 +0000
Subject: [PATCH 2/2] add check for a missing specified config file

---
 src/flake8/options/config.py   | 6 +++++-
 tests/integration/test_main.py | 2 +-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/flake8/options/config.py b/src/flake8/options/config.py
index d7519df..7cba936 100644
--- a/src/flake8/options/config.py
+++ b/src/flake8/options/config.py
@@ -8,6 +8,7 @@ from typing import List
 from typing import Optional
 from typing import Tuple
 
+from flake8 import exceptions
 from flake8.options.manager import OptionManager
 
 LOG = logging.getLogger(__name__)
@@ -60,7 +61,10 @@ def load_config(
 
     cfg = configparser.RawConfigParser()
     if config is not None:
-        cfg.read(config)
+        if not cfg.read(config):
+            raise exceptions.ExecutionError(
+                f"The specified config file does not exist: {config}"
+            )
         cfg_dir = os.path.dirname(config)
     else:
         cfg_dir = pwd
diff --git a/tests/integration/test_main.py b/tests/integration/test_main.py
index 90877d3..fe254b7 100644
--- a/tests/integration/test_main.py
+++ b/tests/integration/test_main.py
@@ -394,7 +394,7 @@ def test_config_file_not_found(tmpdir, capsys):
 
     expected = """\
 There was a critical error during execution of Flake8:
-The specified config file does not exist
+The specified config file does not exist: missing.cfg
 """
 
     with tmpdir.as_cwd():