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Write tests with Testcontainers

Create src/customer-repository.test.js with the test:

const { Client } = require("pg");
const { PostgreSqlContainer } = require("@testcontainers/postgresql");
const {
  createCustomerTable,
  createCustomer,
  getCustomers,
} = require("./customer-repository");

describe("Customer Repository", () => {
  jest.setTimeout(60000);

  let postgresContainer;
  let postgresClient;

  beforeAll(async () => {
    postgresContainer = await new PostgreSqlContainer().start();
    postgresClient = new Client({
      connectionString: postgresContainer.getConnectionUri(),
    });
    await postgresClient.connect();
    await createCustomerTable(postgresClient);
  });

  afterAll(async () => {
    await postgresClient.end();
    await postgresContainer.stop();
  });

  it("should create and return multiple customers", async () => {
    const customer1 = { id: 1, name: "John Doe" };
    const customer2 = { id: 2, name: "Jane Doe" };

    await createCustomer(postgresClient, customer1);
    await createCustomer(postgresClient, customer2);

    const customers = await getCustomers(postgresClient);
    expect(customers).toEqual([customer1, customer2]);
  });
});

Here's what the test does:

  • The beforeAll block starts a real PostgreSQL container using PostgreSqlContainer. It then creates a pg client connected to the container and sets up the customers table.
  • The afterAll block closes the client connection and stops the container.
  • The test inserts two customers, fetches all customers, and asserts the results match.

The test timeout is set to 60 seconds to allow time for the container to start on the first run (when the Docker image needs to be pulled).

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