ArgSuite: enter empty directory

Author: elazarg

mypy/options.py

@@ -131,7 +131,7 @@ def __init__(self) -> None:
         self.scripts_are_modules = False
 
         # Config file name
-        self.config_file = 'setup.cfg'  # type: Optional[str]
+        self.config_file = None  # type: Optional[str]
 
         # Write junit.xml to given file
         self.junit_xml = None  # type: Optional[str]

mypy/test/testargs.py

@@ -8,10 +8,17 @@
 from mypy.test.helpers import Suite, assert_equal
 from mypy.options import Options
 from mypy.main import process_options
+import tempfile
+import os
 
 
 class ArgSuite(Suite):
     def test_coherence(self) -> None:
-        options = Options()
-        _, parsed_options = process_options([], require_targets=False)
-        assert_equal(options, parsed_options)
+        old_cwd = os.getcwd()
+        with tempfile.TemporaryDirectory(prefix='mypy-test-') as tmpdir:
+            # Enter directory to avoid finding 'setup.cfg'
+            os.chdir(tmpdir)
+            options = Options()
+            _, parsed_options = process_options([], require_targets=False)
+            assert_equal(options, parsed_options)
+        os.chdir(old_cwd)