Created ImageDownloader test

test/mocks/WindowMock.ts

@@ -0,0 +1,18 @@
+import { Mock } from 'ts-mockery';
+
+const createLinkMock = () => ({
+  setAttribute: jest.fn(),
+  click: jest.fn(),
+  style: {},
+});
+
+export const appendChild = jest.fn();
+
+export const removeChild = jest.fn();
+
+export const windowMock = Mock.of<Window>({
+  document: {
+    createElement: jest.fn(createLinkMock),
+    body: { appendChild, removeChild },
+  },
+});