Test Utility function that creates a mock file with specified name, size and MIMETYPE

MockFile.js

/**
 * Creates a file containing the requested parameters.
 *
 * @param {string} name The name of the file, including the extension.
 * @param {number} size The file's size in bytes.
 * @param {string} mimeType The file's MIMETYPE, @see {@link https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types}
 */
export const createMockFile = (name?: string, size?: number, mimeType?: string): File => {
  const fileName = name || 'mock.txt';
  const fileSize = size || 1024;
  const fileMimeType = mimeType || 'plain/txt';

  let fileBits = '';
  for (let i = 0; i < fileSize; i += 1) {
    fileBits += 'a';
  }

  return new File([fileBits], fileName, { type: fileMimeType });
};

describe("Mock file for file upload testing", function () {
    it("should have default values", function() {
    const file = createMockFile();
    expect(file.name).toBe('mock.txt');
    expect(file.size).toBe(1024);
    expect(file.type).toBe('plain/txt');
    });

    it("should have specified values", function () {
    const fileName = 'pic.jpg';
    const fileSize = 1024 * 1024 * 2;
    const fileType = 'image/jpeg';
    const file = createMockFile(fileName, fileSize, fileType);

    expect(file.name).toBe(fileName);
    expect(file.size).toBe(fileSize);
    expect(file.type).toBe(fileType);
    });
});