diff --git a/tests/basic/test_main.py b/tests/basic/test_main.py
index ea56645a1..aa994b8b0 100644
--- a/tests/basic/test_main.py
+++ b/tests/basic/test_main.py
@@ -6,6 +6,7 @@ from io import StringIO
 from pathlib import Path
 from unittest import TestCase
 from unittest.mock import MagicMock, patch
+import pytest
 
 import git
 from prompt_toolkit.input import DummyInput
@@ -405,8 +406,15 @@ class TestMain(TestCase):
             self.assertRegex(relevant_output, r"AIDER_DARK_MODE:\s+on")
             self.assertRegex(relevant_output, r"dark_mode:\s+True")
 
-    @pytest.mark.parametrize(desc):
-    def test_yaml_config_file_loading(self):
+    @pytest.mark.parametrize(
+        "scenario",
+        [
+            "yml_only",     # Test with only .yml files
+            "yaml_only",    # Test with only .yaml files
+            "both_formats", # Test with both .yml and .yaml files
+        ],
+    )
+    def test_yaml_config_file_loading(self, scenario):
         with GitTemporaryDirectory() as git_dir:
             git_dir = Path(git_dir)
 
@@ -420,7 +428,7 @@ class TestMain(TestCase):
             cwd.mkdir()
             os.chdir(cwd)
 
-            # Create .aider.conf.yml files in different locations
+            # Create config files in different locations based on scenario
             home_config_yml = fake_home / ".aider.conf.yml"
             home_config_yaml = fake_home / ".aider.conf.yaml"
             git_config_yml = git_dir / ".aider.conf.yml"
@@ -429,10 +437,26 @@ class TestMain(TestCase):
             cwd_config_yaml = cwd / ".aider.conf.yaml"
             named_config = git_dir / "named.aider.conf.yml"
 
-            cwd_config_yml.write_text("model: gpt-4-32k\nmap-tokens: 4096\n")
-            git_config_yml.write_text("model: gpt-4\nmap-tokens: 2048\n")
-            home_config_yml.write_text("model: gpt-3.5-turbo\nmap-tokens: 1024\n")
-            named_config.write_text("model: gpt-4-1106-preview\nmap-tokens: 8192\n")
+            # Create files based on the scenario
+            if scenario == "yml_only":
+                cwd_config_yml.write_text("model: gpt-4-32k\nmap-tokens: 4096\n")
+                git_config_yml.write_text("model: gpt-4\nmap-tokens: 2048\n")
+                home_config_yml.write_text("model: gpt-3.5-turbo\nmap-tokens: 1024\n")
+                named_config.write_text("model: gpt-4-1106-preview\nmap-tokens: 8192\n")
+            elif scenario == "yaml_only":
+                cwd_config_yaml.write_text("model: gpt-4-32k\nmap-tokens: 4096\n")
+                git_config_yaml.write_text("model: gpt-4\nmap-tokens: 2048\n")
+                home_config_yaml.write_text("model: gpt-3.5-turbo\nmap-tokens: 1024\n")
+                named_config.write_text("model: gpt-4-1106-preview\nmap-tokens: 8192\n")
+            else:  # both_formats
+                # Create both formats, with .yaml taking precedence in each directory
+                cwd_config_yml.write_text("model: gpt-4-32k-yml\nmap-tokens: 4096\n")
+                cwd_config_yaml.write_text("model: gpt-4-32k\nmap-tokens: 4096\n")
+                git_config_yml.write_text("model: gpt-4-yml\nmap-tokens: 2048\n")
+                git_config_yaml.write_text("model: gpt-4\nmap-tokens: 2048\n")
+                home_config_yml.write_text("model: gpt-3.5-turbo-yml\nmap-tokens: 1024\n")
+                home_config_yaml.write_text("model: gpt-3.5-turbo\nmap-tokens: 1024\n")
+                named_config.write_text("model: gpt-4-1106-preview\nmap-tokens: 8192\n")
 
             with (
                 patch("pathlib.Path.home", return_value=fake_home),
@@ -451,20 +475,33 @@ class TestMain(TestCase):
                 # Test loading from current working directory
                 main(["--yes", "--exit"], input=DummyInput(), output=DummyOutput())
                 _, kwargs = MockCoder.call_args
-                print("kwargs:", kwargs)  # Add this line for debugging
                 self.assertIn("main_model", kwargs, "main_model key not found in kwargs")
                 self.assertEqual(kwargs["main_model"].name, "gpt-4-32k")
                 self.assertEqual(kwargs["map_tokens"], 4096)
 
-                # Test loading from git root
-                cwd_config_yml.unlink()
+                # Test loading from git root by removing cwd config files
+                if scenario == "yml_only":
+                    cwd_config_yml.unlink()
+                elif scenario == "yaml_only":
+                    cwd_config_yaml.unlink()
+                else:  # both_formats
+                    cwd_config_yml.unlink()
+                    cwd_config_yaml.unlink()
+                
                 main(["--yes", "--exit"], input=DummyInput(), output=DummyOutput())
                 _, kwargs = MockCoder.call_args
                 self.assertEqual(kwargs["main_model"].name, "gpt-4")
                 self.assertEqual(kwargs["map_tokens"], 2048)
 
-                # Test loading from home directory
-                git_config_yml.unlink()
+                # Test loading from home directory by removing git root config files
+                if scenario == "yml_only":
+                    git_config_yml.unlink()
+                elif scenario == "yaml_only":
+                    git_config_yaml.unlink()
+                else:  # both_formats
+                    git_config_yml.unlink()
+                    git_config_yaml.unlink()
+                
                 main(["--yes", "--exit"], input=DummyInput(), output=DummyOutput())
                 _, kwargs = MockCoder.call_args
                 self.assertEqual(kwargs["main_model"].name, "gpt-3.5-turbo")