Initial implementation of generic Excel-to-DB import tool

Supports .xls and .xlsx, Oracle and PostgreSQL via SQLAlchemy.
Includes CLI (run/inspect/generate-config), YAML config, auto schema
detection, and append/replace/upsert modes.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_importer.py

@@ -0,0 +1,80 @@
+from pathlib import Path
+import pandas as pd
+import pytest
+from sqlalchemy import create_engine, text
+
+from excel_import.config import ImportConfig, SheetConfig, ColumnMapping
+from excel_import.importer import Importer
+
+
+@pytest.fixture
+def xlsx_file(tmp_path: Path) -> Path:
+    path = tmp_path / "data.xlsx"
+    df = pd.DataFrame({
+        "id": [1, 2, 3],
+        "name": ["Alice", "Bob", "Carol"],
+        "amount": [100.0, 200.5, 300.0],
+    })
+    df.to_excel(path, index=False)
+    return path
+
+
+@pytest.fixture
+def sqlite_config(xlsx_file):
+    return ImportConfig(
+        dsn="sqlite:///:memory:",
+        sheets=[
+            SheetConfig(
+                sheet=0,
+                target_table="persons",
+                mode="append",
+            )
+        ],
+    )
+
+
+def test_import_append(xlsx_file, sqlite_config):
+    importer = Importer(sqlite_config)
+    results = importer.run(xlsx_file)
+    assert results["persons"] == 3
+
+    with importer.engine.connect() as conn:
+        rows = conn.execute(text("SELECT COUNT(*) FROM persons")).scalar()
+    assert rows == 3
+
+
+def test_import_replace(xlsx_file, tmp_path):
+    cfg = ImportConfig(
+        dsn="sqlite:///:memory:",
+        sheets=[SheetConfig(sheet=0, target_table="persons", mode="replace")],
+    )
+    importer = Importer(cfg)
+    importer.run(xlsx_file)
+    results = importer.run(xlsx_file)  # second run should truncate+insert
+    assert results["persons"] == 3
+
+    with importer.engine.connect() as conn:
+        rows = conn.execute(text("SELECT COUNT(*) FROM persons")).scalar()
+    assert rows == 3
+
+
+def test_import_creates_table(xlsx_file, sqlite_config):
+    importer = Importer(sqlite_config)
+    importer.run(xlsx_file)
+
+    from sqlalchemy import inspect
+    insp = inspect(importer.engine)
+    assert "persons" in insp.get_table_names()
+
+
+def test_import_empty_sheet(tmp_path):
+    path = tmp_path / "empty.xlsx"
+    pd.DataFrame({"a": [], "b": []}).to_excel(path, index=False)
+
+    cfg = ImportConfig(
+        dsn="sqlite:///:memory:",
+        sheets=[SheetConfig(sheet=0, target_table="empty_table", mode="append")],
+    )
+    importer = Importer(cfg)
+    results = importer.run(path)
+    assert results["empty_table"] == 0