cypress-mock-graphql.js

import { graphql } from "graphql";
import { makeMockedSchema } from "../../../src/graphQLMock";

const resolve = result => ({
	json: () => Promise.resolve(result),
	text: () => Promise.resolve(JSON.stringify(result)),
	ok: true,
});

const fetchMockFor = schema => (_, { body }) => {
	const { query, variables } = JSON.parse(body);

	return graphql(schema, query, {}, {}, variables).then(resolve);
};

let fetchMock = null;

Cypress.Commands.add("mockGraphQLApi", { prevSubject: false }, (mocks = {}) => {
	fetchMock = fetchMockFor(makeMockedSchema({ mocks }));

	cy.on("window:before:load", win => {
		const originalFetch = win.fetch;

		function fetch(url, ...rest) {
			if (
				fetchMock &&
				url === `https://${Cypress.env("API_SERVICE_DOMAIN")}/query`
			) {
				return fetchMock(url, ...rest);
			} else {
				return originalFetch(url, ...rest);
			}
		}

		cy.stub(win, "fetch")
			.as("jasperApiMock")
			.callsFake(fetch);
	});
});

Cypress.Commands.add(
	"updateMockGraphQLApi",
	{ prevSubject: false },
	(mocks = {}) => {
		if (!fetchMock) {
			throw new Error(
				"updateMockGraphQLApi: Attempted to update the mock function before it has been defined. Ensure you call 'mockGraphQLApi' first",
			);
		}
		fetchMock = fetchMockFor(makeMockedSchema({ mocks }));
	},
);