my-foundry-project/
├── src/myproject/
│   ├── __init__.py
│   ├── pipeline.py          # @transform functions
│   └── utils.py             # Shared logic
├── tests/
│   ├── conftest.py           # Fixtures with sample DataFrames
│   ├── test_pipeline.py      # Transform unit tests
│   └── sample_data/          # CSV/Parquet test fixtures
├── .env                      # FOUNDRY_HOSTNAME, FOUNDRY_TOKEN
├── requirements.txt          # foundry-platform-sdk, pytest, pyspark
└── pyproject.toml

set -euo pipefail
pip install foundry-platform-sdk pyspark pytest pandas
python -c "import foundry; import pyspark; print('Dependencies ready')"

# tests/conftest.py
import pytest
from pyspark.sql import SparkSession

@pytest.fixture(scope="session")
def spark():
    return SparkSession.builder.master("local[2]").appName("test").getOrCreate()

@pytest.fixture
def sample_orders(spark):
    data = [
        ("ORD-001", "alice@company.com", "2026-03-01", 99.99),
        ("ORD-002", "bob@test.com", "2026-03-02", 49.99),      # test email
        (None, "carol@company.com", "2026-03-03", 149.99),       # null ID
    ]
    return spark.createDataFrame(data, ["order_id", "email", "order_date_str", "total"])

# tests/test_pipeline.py
from myproject.pipeline import clean_orders

def test_clean_orders_removes_nulls_and_test_emails(sample_orders):
    result = clean_orders(sample_orders)
    assert result.count() == 1  # Only alice remains
    assert result.columns == ["order_id", "email", "order_date", "total_cents"]
    row = result.first()
    assert row.total_cents == 9999  # 99.99 * 100

# tests/test_api.py
import pytest
from unittest.mock import MagicMock, patch

def test_list_ontology_objects():
    mock_client = MagicMock()
    mock_client.ontologies.OntologyObject.list.return_value.data = [
        MagicMock(properties={"fullName": "Alice", "department": "Engineering"}),
    ]

    result = mock_client.ontologies.OntologyObject.list(
        ontology="test", object_type="Employee", page_size=10
    )
    assert len(result.data) == 1
    assert result.data[0].properties["fullName"] == "Alice"

set -euo pipefail
pytest tests/ -v --tb=short
# Expected: all tests pass against local Spark + mocked API

# scripts/smoke_test.py — runs against real Foundry (needs credentials)
import os, foundry, sys

client = foundry.FoundryClient(
    auth=foundry.UserTokenAuth(
        hostname=os.environ["FOUNDRY_HOSTNAME"],
        token=os.environ["FOUNDRY_TOKEN"],
    ),
    hostname=os.environ["FOUNDRY_HOSTNAME"],
)

try:
    ontologies = list(client.ontologies.Ontology.list())
    print(f"Smoke test passed: {len(ontologies)} ontologies accessible")
except foundry.ApiError as e:
    print(f"Smoke test failed: {e.status_code} {e.message}", file=sys.stderr)
    sys.exit(1)

pip install pytest-watch
ptw tests/ -- -v --tb=short
# Re-runs tests on every file save