Not able to mock fetch API properly in unit tests with jest, specifically .formData()

[jmdalmasso]

I'm trying to figure out how to write unit test for actions. I have an action that use .formData() off of the Request object. This API is not available in the node js fetch implementation used by jest. What is the recommended approach to mock this or use the web api instead? I've tried importing whatwg-fetch in a jest setup file to no avail.

export async function action({ request, context }: ActionFunctionArgs) {
  const { session, cart } = context;

  const [formData, customerAccessToken] = await Promise.all([
    request.formData(),
    session.get("customerAccessToken"),
  ]);
  // res of implementation
  }

The unit test:

describe("cart - action", () => {
  it("should throw an error if no action is provided", async () => {
    const response = await action({
      request: new Request("http://app.com/path"),
      params: {},
      context: {}
    });

    await expect(response).rejects.toThrow("No action provided");
  });
});

Error:

  cart - action
    ✕ should throw an error if no action is provided (2 ms)

  ● cart - action › should throw an error if no action is provided

    TypeError: _Request.formData: Could not parse content as FormData.

I really wish there a little bit more docs on unit testing and not only on component testing. What are most people doing for unit tests in Remix apps? I see many conversations around E2E testing and almost nothing around unit testing. Thanks!

[jmdalmasso]

Nevermind, I realized I wasn't passing the data to my Request....