@applicaster/zapp-react-native-utils/appUtils/imageCache/__tests__/Image.test.js

Applicaster Zapp React Native utilities package

import { Image } from "../Image";

import nock from "nock";
import fs from "fs";
import path from "path";

const testImagePath = path.resolve(__dirname, "./image.jpg");
const testImage = fs.readFileSync(testImagePath).toString();
const base64TestImage = Buffer.from(testImage).toString("base64");
const prefixedWithBase64 = `data:image/png;base64,${base64TestImage}`;
const imageUrl = "http://lorempixel/400/200";
const errorUrl = "http://error/fail";

describe("Image", () => {
  beforeEach(() => {
    nock("http://lorempixel").persist().get("/400/200").reply(200, testImage);

    nock("http://error")
      .persist()
      .get("/fail")
      .reply(404, new Error("image doesn't exist"));
  });

  it("loads the image, and provides it when it is downloaded", (done) => {
    const handler = (_image) => {
      expect(_image).toEqual(image);
      expect(image.ready).toBe(true);
      expect(image.url).toEqual(imageUrl);
      expect(image.get()).toEqual(prefixedWithBase64);
      expect(image.getUri()).toEqual({ uri: prefixedWithBase64 });
      done();
    };

    const errorHandler = (error) => {
      expect(error).toBeUndefined();
      done();
    };

    const image = new Image(imageUrl)
      .on("ready", handler)
      .on("error", errorHandler);

    expect(image.ready).toBe(false);
    expect(image.url).toEqual(imageUrl);
    expect(image.get()).toBe(null);
    expect(image.getUri()).toBe(null);
  });

  it("invokes the error handler if something wrong happened", (done) => {
    const errorHandler = (error) => {
      expect(error).toMatchSnapshot();
      done();
    };

    new Image(errorUrl).on("error", errorHandler);
  });
});