Initial commit: PROMETHEUS v0.1.0 - Prompt optimizer

- Clean architecture (domain/application/infrastructure)
- DSPy-based evolution engine with scoring
- CLI via pyproject.toml entry point
- Unit + integration tests (~300 tests)
- Configs for glm-5.1 and glm-4.5-air models
- Z.AI endpoint integration

tests/unit/test_file_io.py

@@ -0,0 +1,99 @@
+"""Unit tests for YamlPersistence file I/O."""
+from __future__ import annotations
+
+from pathlib import Path
+
+import pytest
+import yaml
+
+from prometheus.infrastructure.file_io import YamlPersistence
+
+
+class TestYamlPersistenceReadConfig:
+    """Tests for read_config YAML loading."""
+
+    def test_roundtrip_write_and_read(self, tmp_path: Path) -> None:
+        persistence = YamlPersistence()
+        data = {
+            "seed_prompt": "You are helpful.",
+            "task_description": "Answer questions.",
+            "max_iterations": 30,
+            "verbose": True,
+        }
+        config_file = tmp_path / "config.yaml"
+        with open(config_file, "w") as f:
+            yaml.dump(data, f)
+
+        result = persistence.read_config(str(config_file))
+
+        assert result == data
+
+    def test_reads_nested_yaml(self, tmp_path: Path) -> None:
+        persistence = YamlPersistence()
+        data = {
+            "model": {"name": "gpt-4o", "temperature": 0.7},
+            "params": [1, 2, 3],
+        }
+        config_file = tmp_path / "nested.yaml"
+        with open(config_file, "w") as f:
+            yaml.dump(data, f)
+
+        result = persistence.read_config(str(config_file))
+
+        assert result["model"]["name"] == "gpt-4o"
+        assert result["params"] == [1, 2, 3]
+
+    def test_missing_file_raises_error(self, tmp_path: Path) -> None:
+        persistence = YamlPersistence()
+        missing = tmp_path / "nonexistent.yaml"
+
+        with pytest.raises(FileNotFoundError):
+            persistence.read_config(str(missing))
+
+    def test_malformed_yaml_raises_error(self, tmp_path: Path) -> None:
+        persistence = YamlPersistence()
+        bad_file = tmp_path / "bad.yaml"
+        bad_file.write_text(": [invalid: {yaml", encoding="utf-8")
+
+        with pytest.raises(yaml.YAMLError):
+            persistence.read_config(str(bad_file))
+
+
+class TestYamlPersistenceWriteResult:
+    """Tests for write_result YAML output."""
+
+    def test_roundtrip_write_result(self, tmp_path: Path) -> None:
+        persistence = YamlPersistence()
+        data = {
+            "optimized_prompt": "Improved prompt.",
+            "initial_score": 0.4,
+            "final_score": 0.85,
+        }
+        output_file = tmp_path / "result.yaml"
+        persistence.write_result(str(output_file), data)
+
+        with open(output_file) as f:
+            loaded = yaml.safe_load(f)
+
+        assert loaded == data
+
+    def test_write_result_creates_valid_yaml(self, tmp_path: Path) -> None:
+        persistence = YamlPersistence()
+        data = {"key": "value", "number": 42}
+        output_file = tmp_path / "out.yaml"
+        persistence.write_result(str(output_file), data)
+
+        content = output_file.read_text()
+        assert "key: value" in content
+        assert "number: 42" in content
+
+    def test_write_result_handles_unicode(self, tmp_path: Path) -> None:
+        persistence = YamlPersistence()
+        data = {"prompt": "Répondez en français. 中文测试"}
+        output_file = tmp_path / "unicode.yaml"
+        persistence.write_result(str(output_file), data)
+
+        with open(output_file, encoding="utf-8") as f:
+            loaded = yaml.safe_load(f)
+
+        assert loaded["prompt"] == "Répondez en français. 中文测试"