Move desktop-related code to "desktop" subfolder (#872)

Summary:
Pull Request resolved: https://github.com/facebook/flipper/pull/872
Move all the JS code related to desktop app to "desktop" subfolder.

The structure of "desktop" folder:
- `src` - JS code of Flipper desktop app executing in Electron Renderer (Chrome) process. This folder also contains all the Flipper plugins in subfolder "src/plugins".
- `static` - JS code of Flipper desktop app bootstrapping executing in Electron Main (Node.js) process
- `pkg` - Flipper packaging lib and CLI tool
- `doctor` - Flipper diagnostics lib and CLI tool
- `scripts` - Build scripts for Flipper desktop app
- `headless` - Headless version of Flipper app
- `headless-tests` - Integration tests running agains Flipper headless version

Reviewed By: passy

Differential Revision: D20249304

fbshipit-source-id: 9a51c63b51b92b758a02fc8ebf7d3d116770efe9

desktop/static/transforms/__tests__/flipper-requires.node.js

@@ -0,0 +1,72 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import {parse} from '@babel/parser';
+import {transformFromAstSync} from '@babel/core';
+import generate from '@babel/generator';
+
+import flipperRequires from '../flipper-requires';
+
+const babelOptions = {
+  ast: true,
+  plugins: [flipperRequires],
+  filename: 'index.js',
+};
+
+test('transform react requires to global object', () => {
+  const src = 'require("react")';
+  const ast = parse(src);
+  const transformed = transformFromAstSync(ast, src, babelOptions).ast;
+  const {code} = generate(transformed);
+  expect(code).toBe('global.React;');
+});
+
+test('transform react-dom requires to global object', () => {
+  const src = 'require("react-dom")';
+  const ast = parse(src);
+  const transformed = transformFromAstSync(ast, src, babelOptions).ast;
+  const {code} = generate(transformed);
+  expect(code).toBe('global.ReactDOM;');
+});
+
+test('transform flipper requires to global object', () => {
+  const src = 'require("flipper")';
+  const ast = parse(src);
+  const transformed = transformFromAstSync(ast, src, babelOptions).ast;
+  const {code} = generate(transformed);
+  expect(code).toBe('global.Flipper;');
+});
+
+test('transform React identifier to global.React', () => {
+  const src = 'React;';
+  const ast = parse(src);
+  const transformed = transformFromAstSync(ast, src, babelOptions).ast;
+  const {code} = generate(transformed);
+  expect(code).toBe('global.React;');
+});
+
+test.skip('throw error when requiring outside the plugin', () => {
+  const src = 'require("../test.js")';
+  const ast = parse(src);
+  expect(() => {
+    transformFromAstSync(ast, src, babelOptions);
+  }).toThrow();
+});
+
+test('allow requiring from parent folder as long as we stay in plugin folder', () => {
+  const src = 'require("../test.js")';
+  const ast = parse(src);
+  const transformed = transformFromAstSync(ast, src, {
+    ...babelOptions,
+    root: '/path/to/plugin',
+    filename: '/path/to/plugin/subfolder/index.js',
+  }).ast;
+  const {code} = generate(transformed);
+  expect(code).toBe('require("../test.js");');
+});