pg-tx/src/index.test.ts

Transaction wrapper for node-postgres

import { Pool, PoolClient } from 'pg'
import { mock, instance, when, anything, verify } from 'ts-mockito'
import tx from '.'

function testWithClient<TClient extends Pool | PoolClient>(
	makeClient: () => Promise<TClient>,
	destroyClient: (pg: TClient) => Promise<void>
) {
	let pg: TClient

	beforeEach(async () => {
		pg = await makeClient()
		await pg.query(`CREATE TABLE things (
			id SERIAL PRIMARY KEY,
			thing TEXT NOT NULL
		)`)

		// https://dba.stackexchange.com/a/293929/200560
		await pg.query(`
			CREATE TABLE test_defer(
				x int CONSTRAINT test_me UNIQUE DEFERRABLE INITIALLY DEFERRED
			);
		`)
	})

	afterEach(async () => {
		await pg.query(`DROP TABLE things`)
		await pg.query(`DROP TABLE test_defer`)
		await destroyClient(pg)
	})

	it(`commits changes when there's no error`, async () => {
		await tx(pg, async (db) => {
			db.query(`INSERT INTO things (thing) VALUES ('committed')`)
		})

		const {
			rows: [committed]
		} = await pg.query(`SELECT id, thing FROM things WHERE thing = 'committed'`)
		expect(committed).toBeDefined()
		expect(committed.thing).toEqual('committed')
	})

	it(`doesn't commit changes with forcedRollback`, async () => {
		await tx(
			pg,
			async (db) => {
				await db.query(`INSERT INTO things (thing) VALUES ('committed')`)
			},
			true
		)

		const { rowCount } = await pg.query(
			`SELECT id, thing FROM things WHERE thing = 'committed'`
		)
		expect(rowCount).toBe(0)
	})

	it(`doesn't commit changes when there's a Node exception`, async () => {
		await expect(
			tx(pg, async (db) => {
				await db.query(`INSERT INTO things (thing) VALUES ('node_error')`)
				throw new Error(`node error`)
			})
		).rejects.toThrowError(`node error`)

		const { rowCount } = await pg.query(
			`SELECT id, thing FROM things WHERE thing = 'node_error'`
		)
		expect(rowCount).toBe(0)
	})

	it(`doesn't commit changes when there's a query error`, async () => {
		await expect(
			tx(pg, async (db) => {
				await db.query(`INSERT INTO things(thing) VALUES ('query_error')`)
				await db.query(`this query has an error`)
			})
		).rejects.toThrowErrorMatchingInlineSnapshot(
			`"syntax error at or near \\"this\\""`
		)

		const { rowCount } = await pg.query(
			`SELECT id, thing FROM things WHERE thing = 'query_error'`
		)
		expect(rowCount).toBe(0)
	})

	it(`doesn't commit changes on next tick after query error`, async () => {
		let laterPromise
		const txPromise = tx(pg, async (db) => {
			laterPromise = (async () => {
				try {
					await txPromise
				} catch (e) {
					// ignore error, we just needed to wait until it completed
				}
				await new Promise((resolve) => {
					setImmediate(resolve)
				})
				await db.query(`INSERT INTO things(thing) VALUES ('query_error_tick')`)
			})()
			await Promise.all([db.query(`this query has an error`), laterPromise])
		})

		await expect(txPromise).rejects.toThrowErrorMatchingInlineSnapshot(
			`"syntax error at or near \\"this\\""`
		)

		await expect(laterPromise).rejects.toThrowErrorMatchingInlineSnapshot(
			`"Transaction client already released, see more: https://tinyurl.com/py2upfcw"`
		)

		const { rowCount } = await pg.query(
			`SELECT id, thing FROM things WHERE thing = 'query_error_tick'`
		)
		expect(rowCount).toBe(0)
	})

	it(`handles nested transactions`, async () => {
		await tx(pg, async (rootDb) => {
			await tx(rootDb, async (comittedDb) => {
				await comittedDb.query(
					`INSERT INTO things (thing) VALUES ('committed')`
				)
			})
			await expect(
				tx(rootDb, async (rolledbackDb) => {
					await rolledbackDb.query(
						`INSERT INTO things (thing) VALUES ('rolledback')`
					)
					throw new Error(`rollback this block`)
				})
			).rejects.toThrowError(`rollback this block`)
		})
		const { rowCount: comittedCount } = await pg.query(
			`SELECT id, thing FROM things WHERE thing = 'committed'`
		)
		expect(comittedCount).toBe(1)
		const { rowCount: rolledbackCount } = await pg.query(
			`SELECT id, thing FROM things WHERE thing = 'rolledback'`
		)
		expect(rolledbackCount).toBe(0)
	})

	it(`handles errors thrown on commit gracefully`, async () => {
		await expect(tx(pg, async (db) => {
			await expect(db.query(`INSERT INTO test_defer VALUES(1)`)).resolves.toEqual(expect.anything())
			await expect(db.query(`INSERT INTO test_defer VALUES(1)`)).resolves.toEqual(expect.anything())
		})).rejects.toThrowError(`duplicate key value violates unique constraint \"test_me\"`)
	})
}

describe(`tx`, () => {
	describe('with Pool client', () => {
		testWithClient<Pool>(
			async () => {
				const { POSTGRES_URL } = process.env

				if (!POSTGRES_URL) {
					throw new Error('Must specify POSTGRES_URL')
				}

				return new Pool({ connectionString: POSTGRES_URL })
			},
			async (pg) => {
				await pg.end()
			}
		)
	})

	describe('with PoolClient client', () => {
		let pool: Pool
		testWithClient<PoolClient>(
			async () => {
				const { POSTGRES_URL } = process.env

				if (!POSTGRES_URL) {
					throw new Error('Must specify POSTGRES_URL')
				}

				pool = new Pool({ connectionString: POSTGRES_URL })
				return await pool.connect()
			},
			async (pg) => {
				await pg.release()
				await pool.end()
			}
		)
	})

	it(`handles error thrown on commit gracefully`, async () => {
		const clientMock = mock<PoolClient>()
		const exampleQuery = `SELECT 1`

		when( clientMock.query( `SELECT txid_current() AS "txid"`))
			.thenResolve({ rows: [{ txid: '1' }] } as any)
			.thenResolve({ rows: [{ txid: '2' }] } as any)
		when(clientMock.query(`COMMIT`)).thenReject(new Error(`db error`))
		when(clientMock.query(`ROLLBACK`)).thenResolve()

		const client = instance(clientMock)

		await expect(
			tx(client, async (db) => {
				await db.query(exampleQuery)
			})
		).rejects.toThrowError(`db error`)

		verify(clientMock.query(exampleQuery, anything(), anything())).called()
		verify(clientMock.query(`COMMIT`)).called()
		verify(clientMock.query(`ROLLBACK`)).never()
	})
})