fixture-foundry 0.2.0

Fixtures and helpers to create AWS infrastructure (via LocalStack) and containerized databases locally for fast, reproducible integration testing.

Fixture Foundry

Pytest fixtures and context managers for ephemeral integration testing infrastructure: LocalStack (AWS services), PostgreSQL containers, and Pulumi deployment automation.

Features

• Session-scoped fixtures: localstack, postgres, container_network
• Context managers: Standalone infrastructure orchestration for dev scripts
• Pulumi Automation: deploy() helper targets LocalStack automatically
• Database seeding: exec_sql_file() loads SQL schemas with transaction support
• URL translation: to_localstack_url() converts AWS Gateway URLs to LocalStack endpoints
• Auto-cleanup: Health checks, retries, and teardown on test completion

Installation

pip install fixture-foundry docker requests pytest psycopg2-binary
# Optional for Pulumi deployment:
pip install pulumi pulumi-aws

Requirements: Python 3.8–3.12, Docker

Quick Start

Setup pytest fixtures in conftest.py

import pytest
from fixture_foundry import localstack, postgres, container_network  # noqa: F401

def pytest_addoption(parser):
    g = parser.getgroup("localstack")
    g.addoption("--teardown", default="true")
    g.addoption("--localstack-port", type=int, default=0)  # 0 = random port
    g.addoption("--database-image", default="postgres:16")

Database with Schema Loading

from pathlib import Path
import psycopg2
from fixture_foundry import postgres, exec_sql_file

@pytest.fixture(scope="session")
def test_db(postgres):
    # Load schema from SQL file
    schema_file = Path(__file__).parent / "schema.sql"
    
    conn = psycopg2.connect(postgres["dsn"])
    conn.autocommit = True  # Required for multi-statement scripts
    exec_sql_file(conn, schema_file)
    conn.close()
    
    yield postgres

Pulumi Deployment to LocalStack

import json
from fixture_foundry import deploy, to_localstack_url

def my_pulumi_program():
    # Your Pulumi resources here
    pulumi.export("api_url", "https://example.execute-api.us-east-1.amazonaws.com")

@pytest.fixture(scope="module") 
def api_stack(test_db, localstack):
    with deploy("my-project", "test", my_pulumi_program, localstack=localstack) as outputs:
        yield outputs

@pytest.fixture(scope="module")
def api_endpoint(api_stack, localstack):
    # Convert AWS Gateway URL to LocalStack endpoint
    aws_url = api_stack["api_url"]
    yield to_localstack_url(aws_url, localstack["port"])

def test_api_call(api_endpoint):
    import requests
    response = requests.get(f"{api_endpoint}/health")
    assert response.status_code == 200

Context Managers (for dev scripts)

from pathlib import Path
import psycopg2
from fixture_foundry import postgres_context, localstack_context, deploy, exec_sql_file

# Standalone usage outside pytest
with postgres_context(database="mydb") as pg:
    # Seed database with schema
    conn = psycopg2.connect(pg["dsn"])
    conn.autocommit = True
    exec_sql_file(conn, Path("schema.sql"))
    conn.close()
    
    with localstack_context() as ls:
        with deploy("proj", "stack", program, localstack=ls) as outputs:
            # Infrastructure is now running - execute your dev workflow
            api_url = outputs['endpoint']
            print(f"API deployed at: {api_url}")
            
            # Start frontend dev server, run manual tests, etc.
            # subprocess.run(["npm", "run", "dev"], env={"VITE_API_URL": api_url})
            # Or keep running for interactive development...

API Reference

Fixtures (session-scoped)

Fixture	Yields	Description
container_network	str	Docker bridge network name (default: "ls-dev")
postgres	dict	PostgreSQL container with dsn, host_port, container_name, credentials
localstack	dict	LocalStack container with endpoint_url, port, region, services

Functions

Function	Purpose
deploy(project, stack, program, localstack=None, teardown=True)	Pulumi Automation API context manager
exec_sql_file(conn, path)	Execute SQL file (supports multi-statement, DO $$ blocks)
to_localstack_url(aws_url, edge_port=4566)	Convert AWS Gateway URL to LocalStack endpoint

Connection Patterns

• Container-to-container: Use postgres["container_name"]:5432 (Docker network)
• Host-to-container: Use localhost:{postgres["host_port"]} (port mapping)
• Lambda-to-DB: Requires shared Docker network (automatic with LocalStack)

Environment Variables

• AWS_REGION / AWS_DEFAULT_REGION: AWS region (default: us-east-1)
• DOCKER_TEST_NETWORK: Override network name (default: ls-dev)
• LAMBDA_DOCKER_NETWORK: Set by LocalStack for container connectivity

CLI Options

Add to your conftest.py via pytest_addoption():

• --teardown=true|false: Control resource cleanup
• --localstack-port=0: LocalStack port (0 = random)
• --database-image=postgres:16: PostgreSQL Docker image
• --localstack-image=localstack/localstack:latest: LocalStack image