test: add unit tests for config loader module

tests/test_loader.py

@@ -0,0 +1,125 @@
+import pytest
+from pathlib import Path
+from unittest.mock import patch, MagicMock
+from config.loader import (
+    get_system_config_path,
+    _parse_toml,
+    _get_project_config,
+    _merge_dicts,
+    load_config,
+)
+from utils.errors import ConfigError
+def test_load_config_from_system_config(tmp_path):
+    system_toml = tmp_path / "config.toml"
+    system_toml.write_bytes(b'[llm]\nmodel = "gpt-4"\n')
+
+    with patch("config.loader.get_system_config_path", return_value=system_toml):
+        with patch("config.loader._get_project_config", return_value=None):
+            with patch("config.loader.Config") as MockConfig:
+                MockConfig.return_value = MagicMock()
+                load_config(tmp_path)
+                call_kwargs = MockConfig.call_args[1]
+                assert call_kwargs.get("llm", {}).get("model") == "gpt-4"
+def test_load_config_skips_missing_system_config(tmp_path):
+    missing_path = tmp_path / "nonexistent.toml"
+
+    with patch("config.loader.get_system_config_path", return_value=missing_path):
+        with patch("config.loader._get_project_config", return_value=None):
+            with patch("config.loader.Config") as MockConfig:
+                MockConfig.return_value = MagicMock()
+                load_config(tmp_path)
+                MockConfig.assert_called_once()
+def test_load_config_from_project_config(tmp_path):
+    agent_dir = tmp_path / ".ai-agent"
+    agent_dir.mkdir()
+    project_toml = agent_dir / "config.toml"
+    project_toml.write_bytes(b'[llm]\nmodel = "gpt-3.5"\n')
+
+    missing_system = tmp_path / "nonexistent.toml"
+
+    with patch("config.loader.get_system_config_path", return_value=missing_system):
+        with patch("config.loader.Config") as MockConfig:
+            MockConfig.return_value = MagicMock()
+            load_config(tmp_path)
+            call_kwargs = MockConfig.call_args[1]
+            assert call_kwargs.get("llm", {}).get("model") == "gpt-3.5"
+def test_project_config_overrides_system_config(tmp_path):
+    system_toml = tmp_path / "system.toml"
+    system_toml.write_bytes(b'[llm]\nmodel = "gpt-4"\n')
+
+    agent_dir = tmp_path / ".ai-agent"
+    agent_dir.mkdir()
+    project_toml = agent_dir / "config.toml"
+    project_toml.write_bytes(b'[llm]\nmodel = "gpt-3.5"\n')
+
+    with patch("config.loader.get_system_config_path", return_value=system_toml):
+        with patch("config.loader.Config") as MockConfig:
+            MockConfig.return_value = MagicMock()
+            load_config(tmp_path)
+            call_kwargs = MockConfig.call_args[1]
+            assert call_kwargs.get("llm", {}).get("model") == "gpt-3.5"
+def test_parse_toml_raises_config_error_on_invalid_toml(tmp_path):
+    bad_toml = tmp_path / "bad.toml"
+    bad_toml.write_bytes(b"invalid = [unclosed")
+    with pytest.raises(ConfigError):
+        _parse_toml(bad_toml)
+def test_parse_toml_raises_config_error_on_missing_file(tmp_path):
+    missing = tmp_path / "missing.toml"
+    with pytest.raises(ConfigError):
+        _parse_toml(missing)
+def test_parse_toml_success(tmp_path):
+    good_toml = tmp_path / "good.toml"
+    good_toml.write_bytes(b'[section]\nkey = "value"\n')
+    result = _parse_toml(good_toml)
+    assert result == {"section": {"key": "value"}}
+def test_load_config_skips_invalid_system_config(tmp_path, caplog):
+    bad_system = tmp_path / "bad.toml"
+    bad_system.write_bytes(b"invalid = [unclosed")
+
+    with patch("config.loader.get_system_config_path", return_value=bad_system):
+        with patch("config.loader._get_project_config", return_value=None):
+            with patch("config.loader.Config") as MockConfig:
+                MockConfig.return_value = MagicMock()
+                load_config(tmp_path)
+                MockConfig.assert_called_once()
+def test_get_project_config_returns_none_when_no_agent_dir(tmp_path):
+    result = _get_project_config(tmp_path)
+    assert result is None
+def test_get_project_config_returns_none_when_no_config_file(tmp_path):
+    agent_dir = tmp_path / ".ai-agent"
+    agent_dir.mkdir()
+    result = _get_project_config(tmp_path)
+    assert result is None
+def test_get_project_config_returns_path_when_exists(tmp_path):
+    agent_dir = tmp_path / ".ai-agent"
+    agent_dir.mkdir()
+    config_file = agent_dir / "config.toml"
+    config_file.write_bytes(b"")
+    result = _get_project_config(tmp_path)
+    assert result == config_file
+def test_merge_dicts_override_simple_value():
+    base = {"key": "base_value"}
+    override = {"key": "new_value"}
+    result = _merge_dicts(base, override)
+    assert result["key"] == "new_value"
+def test_merge_dicts_deep_merge():
+    base = {"llm": {"model": "gpt-4", "temperature": 0.7}}
+    override = {"llm": {"model": "gpt-3.5"}}
+    result = _merge_dicts(base, override)
+    assert result["llm"]["model"] == "gpt-3.5"
+    assert result["llm"]["temperature"] == 0.7
+def test_merge_dicts_does_not_modify_base():
+    base = {"key": "original"}
+    override = {"key": "changed"}
+    _merge_dicts(base, override)
+    assert base["key"] == "original"
+def test_environment_variable_override(tmp_path, monkeypatch):
+    monkeypatch.setenv("AI_AGENT_MODEL", "gpt-env")
+    missing_system = tmp_path / "nonexistent.toml"
+
+    with patch("config.loader.get_system_config_path", return_value=missing_system):
+        with patch("config.loader._get_project_config", return_value=None):
+            with patch("config.loader.Config") as MockConfig:
+                MockConfig.return_value = MagicMock()
+                load_config(tmp_path)
+                MockConfig.assert_called_once()