feat(config): add warning for multiple configuration files and update documentation

commitizen/config/__init__.py

@@ -3,7 +3,7 @@
 from pathlib import Path
 from typing import TYPE_CHECKING
 
-from commitizen import defaults, git
+from commitizen import defaults, git, out
 from commitizen.config.factory import create_config
 from commitizen.exceptions import ConfigFileIsEmpty, ConfigFileNotFound
 
@@ -35,7 +35,20 @@ def _resolve_config_paths(filepath: str | None = None) -> Generator[Path, None,
 
 
 def read_cfg(filepath: str | None = None) -> BaseConfig:
-    for filename in _resolve_config_paths(filepath):
+    config_candidates = list(_resolve_config_paths(filepath))
+
+    # Check for multiple config files and warn the user
+    config_candidates_exclude_pyproject = [
+        path for path in config_candidates if path.name != "pyproject.toml"
+    ]
+    if len(config_candidates_exclude_pyproject) > 1:
+        filenames = [path.name for path in config_candidates_exclude_pyproject]
+        out.warn(
+            f"Multiple config files detected: {', '.join(filenames)}. "
+            f"Using config file: '{filenames[0]}'."
+        )
+
+    for filename in config_candidates:
         with open(filename, "rb") as f:
             data: bytes = f.read()
 

docs/config/configuration_file.md

@@ -31,6 +31,9 @@ The first valid configuration file found will be used. If no configuration file
 !!! tip
     For Python projects, it's recommended to add your Commitizen configuration to `pyproject.toml` to keep all project configuration in one place.
 
+!!! warning "Multiple Configuration Files"
+    If Commitizen detects more than one configuration file in your project directory (excluding `pyproject.toml`), it will display a warning message and identify which file is being used. To avoid confusion, ensure you have only one Commitizen configuration file in your project.
+
 ## Supported Formats
 
 Commitizen supports three configuration file formats:

tests/test_conf.py

@@ -239,6 +239,90 @@ def test_load_empty_pyproject_toml_from_config_argument(_, tmpdir):
             with pytest.raises(ConfigFileIsEmpty):
                 config.read_cfg(filepath="./not_in_root/pyproject.toml")
 
+    def test_warn_multiple_config_files(_, tmpdir, capsys):
+        """Test that a warning is issued when multiple config files exist."""
+        with tmpdir.as_cwd():
+            # Create multiple config files
+            tmpdir.join(".cz.toml").write(PYPROJECT)
+            tmpdir.join(".cz.json").write(JSON_STR)
+
+            # Read config
+            cfg = config.read_cfg()
+
+            # Check that the warning was issued
+            captured = capsys.readouterr()
+            assert "Multiple config files detected" in captured.err
+            assert ".cz.toml" in captured.err
+            assert ".cz.json" in captured.err
+            assert "Using" in captured.err
+
+            # Verify the correct config is loaded (first in priority order)
+            assert cfg.settings == _settings
+
+    def test_warn_multiple_config_files_with_pyproject(_, tmpdir, capsys):
+        """Test warning excludes pyproject.toml from the warning message."""
+        with tmpdir.as_cwd():
+            # Create multiple config files including pyproject.toml
+            tmpdir.join("pyproject.toml").write(PYPROJECT)
+            tmpdir.join(".cz.json").write(JSON_STR)
+
+            # Read config - should use pyproject.toml (first in priority)
+            cfg = config.read_cfg()
+
+            # No warning should be issued as only one non-pyproject config exists
+            captured = capsys.readouterr()
+            assert "Multiple config files detected" not in captured.err
+
+            # Verify the correct config is loaded
+            assert cfg.settings == _settings
+
+    def test_warn_multiple_config_files_uses_correct_one(_, tmpdir, capsys):
+        """Test that the correct config file is used when multiple exist."""
+        with tmpdir.as_cwd():
+            # Create .cz.json with different settings
+            json_different = """
+            {
+                "commitizen": {
+                    "name": "cz_conventional_commits",
+                    "version": "2.0.0"
+                }
+            }
+            """
+            tmpdir.join(".cz.json").write(json_different)
+            tmpdir.join(".cz.toml").write(PYPROJECT)
+
+            # Read config - should use pyproject.toml (first in defaults.CONFIG_FILES)
+            # But since pyproject.toml doesn't exist, .cz.toml is second in priority
+            cfg = config.read_cfg()
+
+            # Check that warning mentions both files
+            captured = capsys.readouterr()
+            assert "Multiple config files detected" in captured.err
+            assert ".cz.toml" in captured.err
+            assert ".cz.json" in captured.err
+
+            # Verify .cz.toml was used (second in priority after pyproject.toml)
+            assert cfg.settings["name"] == "cz_jira"  # from PYPROJECT
+            assert cfg.settings["version"] == "1.0.0"
+
+    def test_no_warn_with_explicit_config_path(_, tmpdir, capsys):
+        """Test that no warning is issued when user explicitly specifies config."""
+        with tmpdir.as_cwd():
+            # Create multiple config files
+            tmpdir.join(".cz.toml").write(PYPROJECT)
+            tmpdir.join(".cz.json").write(JSON_STR)
+
+            # Read config with explicit path
+            cfg = config.read_cfg(filepath=".cz.json")
+
+            # No warning should be issued
+            captured = capsys.readouterr()
+            assert "Multiple config files detected" not in captured.err
+
+            # Verify the explicitly specified config is loaded (compare to expected JSON config)
+            json_cfg_expected = JsonConfig(data=JSON_STR, path=Path(".cz.json"))
+            assert cfg.settings == json_cfg_expected.settings
+
 
 @pytest.mark.parametrize(
     "config_file, exception_string",