🚀 Testing with AVA

We'll now add tests with AVAOpen external link to our previous esbuild example. See this repositoryOpen external link for a complete example.

​Dependencies

# Install ava as a dev dependency
$ npm install -D ava

Enable ES modules mode, and add a new test script in package.json:

package.json
{
  ...,
  "type": "module",
  "scripts": {
    ...
    "test": "npm run build && ava --verbose test/*.spec.js"
  },
  ...
}

​Isolated Tests

Create the following file containing our tests:

test/index.spec.js
import test from "ava";
import { Miniflare } from "miniflare";

test.beforeEach((t) => {
  // Create a new Miniflare environment for each test
  const mf = new Miniflare({
    // Autoload configuration from `.env`, `package.json` and `wrangler.toml`
    envPath: true,
    packagePath: true,
    wranglerConfigPath: true,
    // We don't want to rebuild our worker for each test, we're already doing
    // it once before we run all tests in package.json, so disable it here.
    // This will override the option in wrangler.toml.
    buildCommand: undefined,
  });
  t.context = { mf };
});

test("increments path count for new paths", async (t) => {
  // Get the Miniflare instance
  const { mf } = t.context;
  // Dispatch a fetch event to our worker
  const res = await mf.dispatchFetch("http://localhost:8787/a");
  // Check the count is "1" as this is the first time we've been to this path
  t.is(await res.text(), "1");
});

You can run the tests with:

$ npm test

​Manipulating KV

Let's try set an initial count in KV before we make our request to make sure our worker works with existing counts. Add the following code to test/index.spec.js:

test/index.spec.js
test("increments path count for existing paths", async (t) => {
  // Get the Miniflare instance
  const { mf } = t.context;
  // Get the counter KV namespace
  const ns = await mf.getKVNamespace("COUNTER_NAMESPACE");
  // Set an initial count of 5
  await ns.put("/a", "5");
  // Dispatch a fetch event to our worker
  const res = await mf.dispatchFetch("http://localhost:8787/a");
  // Check returned count is now "6"
  t.is(await res.text(), "6");
  // Check KV count is now "6" too
  t.is(await ns.get("/a"), "6");
});

​More Examples

For more examples of testing workers with AVA, Miniflare uses AVA for its own testingOpen external link.