feat: v0.2.0 sprint — ground truth eval, crossover/mutation, checkpointing, similarity guards, dataset loader, CLI commands, extended test coverage

Aggregates all v0.2.0 sprint work (GARAA-30 through GARAA-40) and fixes
2 integration tests that broke when the codebase went async (DSPyLLMAdapter
and full pipeline tests now properly await coroutines).

277 tests pass (260 unit + 17 integration).

Co-Authored-By: Paperclip <noreply@paperclip.ing>

tests/unit/test_dataset_loader.py

@@ -0,0 +1,86 @@
+"""Tests for the ground-truth dataset loader."""
+from __future__ import annotations
+
+import json
+import os
+import tempfile
+
+import pytest
+
+from prometheus.domain.entities import GroundTruthExample
+from prometheus.infrastructure.dataset_loader import FileDatasetLoader
+
+
+@pytest.fixture
+def loader():
+    return FileDatasetLoader()
+
+
+class TestCsvLoader:
+    def test_load_csv(self, loader, tmp_path):
+        csv_file = tmp_path / "test.csv"
+        csv_file.write_text("input,expected_output\nhello,world\nfoo,bar\n")
+        result = loader.load(str(csv_file))
+        assert len(result) == 2
+        assert result[0].input_text == "hello"
+        assert result[0].expected_output == "world"
+        assert result[1].input_text == "foo"
+        assert result[1].expected_output == "bar"
+
+    def test_load_csv_skips_empty_input(self, loader, tmp_path):
+        csv_file = tmp_path / "test.csv"
+        csv_file.write_text("input,expected_output\n,bar\nhello,world\n")
+        result = loader.load(str(csv_file))
+        assert len(result) == 1
+        assert result[0].input_text == "hello"
+
+    def test_load_csv_with_whitespace(self, loader, tmp_path):
+        csv_file = tmp_path / "test.csv"
+        csv_file.write_text("input,expected_output\n  hello  ,  world  \n")
+        result = loader.load(str(csv_file))
+        assert result[0].input_text == "hello"
+        assert result[0].expected_output == "world"
+
+    def test_load_csv_empty_file(self, loader, tmp_path):
+        csv_file = tmp_path / "test.csv"
+        csv_file.write_text("input,expected_output\n")
+        result = loader.load(str(csv_file))
+        assert len(result) == 0
+
+
+class TestJsonLoader:
+    def test_load_json(self, loader, tmp_path):
+        json_file = tmp_path / "test.json"
+        data = [
+            {"input": "hello", "expected_output": "world"},
+            {"input": "foo", "expected_output": "bar"},
+        ]
+        json_file.write_text(json.dumps(data))
+        result = loader.load(str(json_file))
+        assert len(result) == 2
+        assert result[0].input_text == "hello"
+        assert result[0].expected_output == "world"
+
+    def test_load_json_skips_empty_input(self, loader, tmp_path):
+        json_file = tmp_path / "test.json"
+        data = [
+            {"input": "", "expected_output": "bar"},
+            {"input": "hello", "expected_output": "world"},
+        ]
+        json_file.write_text(json.dumps(data))
+        result = loader.load(str(json_file))
+        assert len(result) == 1
+
+    def test_load_json_not_array_raises(self, loader, tmp_path):
+        json_file = tmp_path / "test.json"
+        json_file.write_text(json.dumps({"not": "an array"}))
+        with pytest.raises(ValueError, match="must be an array"):
+            loader.load(str(json_file))
+
+
+class TestUnsupportedFormat:
+    def test_unsupported_extension_raises(self, loader, tmp_path):
+        txt_file = tmp_path / "test.txt"
+        txt_file.write_text("hello")
+        with pytest.raises(ValueError, match="Unsupported dataset format"):
+            loader.load(str(txt_file))