Fix test failures: pytest collection warning and validator bug

This commit fixes two test issues discovered in CI:

1. Pytest Collection Warning (test_base_ingestor.py):
   - Renamed TestIngestor to MockIngestor
   - Pytest was incorrectly treating the helper class as a test class
   - The class starts with "Test" but is a concrete implementation for testing
   - Updated all references in fixtures and assertions

2. Validator Test Failures (test_qlib_binary_writer.py):
   - Fixed bug in QlibBinaryValidator._validate_instruments()
   - Instruments file format is tab-separated: SYMBOL\tstart_date\tend_date
   - Validator was not splitting by tab, causing symbol lookups to fail
   - Now properly extracts just the symbol field (first column)
   - This fixes both test_validator_features and test_validator_full

Test Results:
- All 123 unit tests now pass (previously 2 failures, 1 warning)
- test_base_ingestor.py: 11/11 passed
- test_qlib_binary_writer.py: 20/20 passed (including previously failing tests)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: claude

src/transform/qlib_binary_validator.py

@@ -133,7 +133,15 @@ def _validate_instruments(self, data_type: str) -> Dict[str, Any]:
                 return result
 
             with open(instruments_file) as f:
-                symbols = [line.strip() for line in f if line.strip()]
+                # Instruments file format: SYMBOL\tstart_date\tend_date
+                # Extract just the symbol (first field)
+                symbols = []
+                for line in f:
+                    line = line.strip()
+                    if line:
+                        # Split by tab and take first field (symbol)
+                        symbol = line.split('\t')[0]
+                        symbols.append(symbol)
 
             if len(symbols) == 0:
                 result['errors'] = result.get('errors', [])

tests/unit/test_base_ingestor.py

@@ -13,7 +13,7 @@
 from src.ingest.base_ingestor import BaseIngestor, IngestionError
 
 
-class TestIngestor(BaseIngestor):
+class MockIngestor(BaseIngestor):
     """Concrete implementation for testing"""
 
     def ingest_date(self, date, data, symbols=None):
@@ -36,7 +36,7 @@ def test_config():
 @pytest.fixture
 def test_ingestor(tmp_path, test_config):
     """Create test ingestor instance"""
-    return TestIngestor(
+    return MockIngestor(
         data_type='stocks_daily',
         output_root=tmp_path / 'parquet',
         config=test_config
@@ -182,7 +182,7 @@ def test_memory_monitor_integration(test_ingestor):
 def test_repr(test_ingestor):
     """Test string representation"""
     repr_str = repr(test_ingestor)
-    assert 'TestIngestor' in repr_str
+    assert 'MockIngestor' in repr_str
     assert 'stocks_daily' in repr_str