ADD unit tests, split and refactor source code

__test__/assets/untar.spec.js

@@ -0,0 +1,65 @@
+const { EventEmitter } = require('events');
+const zlib = require('zlib');
+const tar = require('tar');
+const untar = require('../../src/assets/untar');
+
+jest.mock('zlib');
+jest.mock('tar', () => ({
+  Extract: jest.fn()
+}));
+
+describe('untar()', () => {
+
+  let ungzEvents, untarEvents, pipe, onSuccess, onError;
+
+  beforeEach(() => {
+    ungzEvents = new EventEmitter();
+    untarEvents = new EventEmitter();
+
+    pipe = jest.fn();
+    onSuccess = jest.fn();
+    onError = jest.fn();
+
+    pipe.mockReturnValueOnce({ pipe });
+    tar.Extract.mockReturnValueOnce(untarEvents);
+    zlib.createGunzip.mockReturnValueOnce(ungzEvents);
+  });
+
+  it('should download resource and untar to given binPath', () => {
+
+    untar({ opts: { binPath: './bin', binName: 'command' }, req: { pipe }, onSuccess, onError });
+
+    expect(tar.Extract).toHaveBeenCalledWith({ path: './bin' });
+  });
+
+  it('should call onSuccess on untar end', () => {
+
+    untar({ opts: { binPath: './bin', binName: 'command' }, req: { pipe }, onSuccess, onError });
+
+    untarEvents.emit('end');
+
+    expect(onSuccess).toHaveBeenCalled();
+  });
+
+  it('should call onError with error on ungz error', () => {
+
+    const error = new Error();
+
+    untar({ opts: { binPath: './bin', binName: 'command' }, req: { pipe }, onSuccess, onError });
+
+    ungzEvents.emit('error', error);
+
+    expect(onError).toHaveBeenCalledWith(error);
+  });
+
+  it('should call onError with error on untar error', () => {
+
+    const error = new Error();
+
+    untar({ opts: { binPath: './bin', binName: 'command' }, req: { pipe }, onSuccess, onError });
+
+    untarEvents.emit('error', error);
+
+    expect(onError).toHaveBeenCalledWith(error);
+  });
+});