import {
    closeTestingConnections,
    createTestingConnections,
    reloadTestingDatabases,
} from "../../utils/test-utils"
import { DataSource } from "../../../src/data-source/DataSource"
import { expect } from "chai"

describe("github issues > #6699 MaxListenersExceededWarning occurs on Postgres", () => {
    let connections: DataSource[]
    before(
        async () =>
            (connections = await createTestingConnections({
                entities: [],
                enabledDrivers: ["postgres"],
            })),
    )
    beforeEach(() => reloadTestingDatabases(connections))
    after(() => closeTestingConnections(connections))

    it("queries in a transaction do not cause an EventEmitter memory leak", () =>
        Promise.all(
            connections.map(async (connection) => {
                await connection.transaction(async (manager) => {
                    const queryPromises = [...Array(10)].map(() =>
                        manager.query("SELECT pg_sleep(0.0001)"),
                    )

                    const pgConnection = await manager.queryRunner!.connect()

                    expect(pgConnection.listenerCount("error")).to.equal(1)

                    // Wait for all of the queries to finish and drain the backlog
                    await Promise.all(queryPromises)
                })
            }),
        ))
})