Fortunately, deploying applications in containers is becoming more commonplace. It's likely that your CI pipeline already has first-class support for running them. However, managing containers programmatically from your application isn't as straightforward. For this reason I've created testcontainers, which I hope simplifies this process.

Code here: https://github.com/cristianrgreco/testcontainers-node.

Imagine you have a requirement to create a cache; you decide on the following interface:

  interface Cache {
    get(key: string): Promise<string>;
    set(key: string, value: string): Promise<void>;
  }

  const redis = require("async-redis");
  const { GenericContainer } = require("testcontainers");

  describe("RedisCache", () => {
    let container;
    let cache;

    beforeAll(async () => {
      container = await new GenericContainer("redis:4.0")
        .withExposedPorts(6379)
        .start();

      const redisClient = redis.createClient(container.getMappedPort(6379));
      cache = new RedisCache(redisClient);
    });

    afterAll(async () => {
      await container.stop();
    });

    it("should cache a value", async () => {
      await cache.set("key", "value");
      expect(await cache.get("key")).toBe("value");
    });
  });

Running tests against the system and all of it's integrations is now as easy as an "npm test".