CheckOptions

CheckOptions is passed as the second argument to proof.check().

interface CheckOptions {
  generate: Record<string, number>;
  setup?: (db: SqlProofClient) => Promise<void>;
  property: (db: SqlProofClient) => Promise<boolean>;
  runs?: number;
  seed?: number;
  timeout?: number;
}

Fields

generate (required)

Per-table row counts. Keys are table names; values are the number of rows to generate per run. Only tables listed here will have data generated.

generate: { customers: 20, orders: 100, line_items: 500 }

property (required)

A function that receives a SqlProofClient and returns Promise<boolean>. Return true if the property holds, false if violated. Throwing also counts as a violation.

property: async (db) => {
  const result = await db.query('SELECT total FROM orders WHERE total < 0');
  return result.rows.length === 0;
}

setup (optional)

Runs after data insertion but before the property check. Use for mutations or additional setup.

setup: async (db) => {
  await db.query(`UPDATE orders SET status = 'confirmed' WHERE total > 100`);
}

runs (optional)

Number of random datasets to generate and test. Default: 100.

seed (optional)

Integer seed for deterministic data generation. Use the seed from a failure report to reproduce it:

await proof.check('order totals are non-negative', {
  generate: { customers: 10, orders: 50 },
  property: async (db) => { /* ... */ },
  seed: 1708891234,
});

timeout (optional)

Per-run timeout in milliseconds. Default: 5000.

SqlProofClient

The db object passed to property and setup:

interface SqlProofClient {
  query(sql: string, params?: unknown[]): Promise<{ rows: Record<string, unknown>[] }>;
  getGeneratedData(): Dataset;
}

• query() — runs SQL against the isolated test schema for the current run
• getGeneratedData() — returns the full inserted dataset (useful for debugging)