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How to mock an unexported function in javascript jest?

I have a module in my vuejs project that i want to test

import { getBaseUrl } from "@/application/api/baseUrl";

export default (
  uri: string,
  requestBody: Record<string, string | number>
): void => {
  let form = document.createElement("form");

  form.method = "POST";
  form.action = `${getBaseUrl()}/${uri}`;

  form = convertToFormData(form, requestBody);
  submitForm(form);
};

function convertToFormData(
  form: HTMLFormElement,
  requestBody: Record<string, string | number>
) {
  for (const [key, value] of Object.entries(requestBody)) {
    const element = document.createElement("input");
    element.name = key;
    element.value = value.toString();
    form.appendChild(element);
  }
  return form;
}

function submitForm(form: HTMLFormElement) {
  document.body.appendChild(form);
  form.submit();
}

I want to test this behavior but I don't want it to actually redirect, so i want to mock submitForm with a simple jest.fn() so that i can check it's behaviour.

I tried to implement rewire using babel for ts but i can't get it to work with the new vue-cli 5.*. These babel packages also seem to be abandoned. Is there another way to test this beheviour?

my test at this point:

import postRedirect from "@/application/util/postRedirect";

const submitFormMock = jest.fn();
jest.mock("@/application/util/postRedirect", () => ({
  ...jest.requireActual('@/application/util/postRedirect'),
  submitForm: submitFormMock,
}));


describe("PostRedirect", () => {
  it("", () => {
    postRedirect("test", { foo: "bar", baz: "foo" });

    expect(submitFormMock).toBeCalled();
    const formDataObject = {} as Record<string, unknown>;

    for (const [key, value] of new FormData(
      submitFormMock.mock.calls[0][0]
    ).entries()) {
      formDataObject[key] = value;
    }

    expect(formDataObject.foo).toBe("bar");
    expect(formDataObject.baz).toBe("foo");
  });
});

I try to mock submitForm but this isn't the way to go, perhaps anyone else knows how to mock this correctly.

update: I'm currently also trying to just export the submitForm anyway even if it's not ment to be exported, but I can't get that to work either. since I have to mock only one named export and not the default export

about 4 years ago · Juan Pablo Isaza
1 Respuestas
Responde la pregunta

0

With a little inspiration of @jonrsharpe i created a new test with the idee that i should not test private methods.

I still find it a little dirty but this is a way of testing that when I call my function that does a redirect using a POST call, that it actually does a submit and that it does have the right attributes in the form that was created.

I'm open for other opinions and ways of testing this, or of ways to redirect the user with a post to another application.

import postRedirect from "@/application/util/postRedirect";

describe("PostRedirect", () => {
  it("", () => {
    const mockSubmit = jest.fn();
    window.HTMLFormElement.prototype.submit = mockSubmit
    postRedirect("test", { foo: "bar", baz: "foo" });
    expect(mockSubmit).toBeCalled();

    // @ts-ignore
    const values = Array.from(new FormData(document.getElementsByTagName("form")[0] as HTMLFormElement));
    
    expect(values[0][0]).toBe("foo");
    expect(values[0][1]).toBe("bar");
    expect(values[1][0]).toBe("baz");
    expect(values[1][1]).toBe("foo");
  });
});
about 4 years ago · Juan Pablo Isaza Denunciar
Responde la pregunta
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