Standardise configuration mechanism (react-native-community#254)

Summary:
---------

This pull requests brings a new way of configuring the CLI and drops never properly standardised and documented "rnpm" configuration.

This is done in order to support new "auto-linking" feature and consolidate the configuration into a single place, that is easy to customise by developers.

### Highlights

Given the scope of this PR, it's hard to write down every tiny detail. I've tried to leave as many comments as possible throughout the code to make it easier for you to navigate and understand some of the code patterns.

Please see the highlighted changes below:

- We now use `cosmiconfig` to load user preferences. We do that by taking "react-native" out of "package.json" and reading "react-native.config.js". We still read "rnpm" for legacy purposes and print appropriate deprecation messages along the instructions on what to do in order to upgrade. Jest validation library makes this kind of things super easy.

- We validate the provided configuration by user using Jest validation library. This gives instant feedback whether the configuration is correct or not.

- We now read configuration in a single place (happens in main CLI file) and pass it down to commands. Previously, we used to call `findPlugins` multiple times w/o cache, causing expensive globs to be performed.

- Project configuration is lazy. We won't glob node_modules and/or look for native files unless you explicitly read for that package configuration.

- Better support for out-of-tree-platforms - no need to define "haste" yourself, we are able to infer it from other properties. The files are also better organised now, causing less of maintenance pain with "linkConfig" 

- We consider our automatically generated configuration a set of defaults. Users can override settings for the project and each of the dependencies. Useful, especially with auto-linking feature to disable certain packages from it or when you don't want to link particular platform automatically. This has been historically really hard to implement

- Global flags (e.g. "reactNativePath") can now be defined in configuration, instead of passing every time around. This fixes issues with "packager.sh" script (starting automatically Metro when running from Xcode) when run from RNTester.xcodeproj

### Next steps

Once this PR is merged, we can concurrently start working/merging other "auto-linking" PRs. In the meantime, I'll submit a PR to move regular "link" (soon to be considered a legacy) to use the new configuration format as well.

The new configuration has been designed in the way to still include previous configuration keys to support "link" and other community packages. 

For now, we print handy deprecation messages to help migrate the community from "rnpm" to "react-native" configuration. 

When "link" gets deprecated/removed forever in favour of "auto-linking", we should revisit the configuration and eventually, remove extraneous keys out of it. With "auto-linking", we don't need majority of it.

Test Plan:
----------

Run `react-native config` to output the configuration.

packages/cli/package.json

@@ -23,6 +23,8 @@
     "commander": "^2.19.0",
     "compression": "^1.7.1",
     "connect": "^3.6.5",
+    "cosmiconfig": "^5.1.0",
+    "deepmerge": "^3.2.0",
     "denodeify": "^1.2.1",
     "envinfo": "^7.1.0",
     "errorhandler": "^1.5.0",
@@ -32,6 +34,7 @@
     "glob": "^7.1.1",
     "graceful-fs": "^4.1.3",
     "inquirer": "^3.0.6",
+    "joi": "^14.3.1",
     "lodash": "^4.17.5",
     "metro": "^0.53.1",
     "metro-config": "^0.53.1",

packages/cli/src/cliEntry.js

@@ -10,22 +10,21 @@
 import chalk from 'chalk';
 import childProcess from 'child_process';
 import commander from 'commander';
-import minimist from 'minimist';
 import path from 'path';
+
 import type {CommandT, ContextT} from './tools/types.flow';
-import getLegacyConfig from './tools/getLegacyConfig';
+
 import {getCommands} from './commands';
 import init from './commands/init/init';
 import assertRequiredOptions from './tools/assertRequiredOptions';
 import logger from './tools/logger';
 import findPlugins from './tools/findPlugins';
 import {setProjectDir} from './tools/PackageManager';
 import pkgJson from '../package.json';
+import loadConfig from './tools/config';
 
 commander
   .option('--version', 'Print CLI version')
-  .option('--projectRoot [string]', 'Path to the root of the project')
-  .option('--reactNativePath [string]', 'Path to React Native')
   .option('--verbose', 'Increase logging verbosity');
 
 commander.on('command:*', () => {
@@ -117,15 +116,6 @@ const addCommand = (command: CommandT, ctx: ContextT) => {
       opt.default,
     ),
   );
-
-  /**
-   * We want every command (like "start", "link") to accept below options.
-   * To achieve that we append them to regular options of each command here.
-   * This way they'll be displayed in the commands --help menus.
-   */
-  cmd
-    .option('--projectRoot [string]', 'Path to the root of the project')
-    .option('--reactNativePath [string]', 'Path to React Native');
 };
 
 async function run() {
@@ -156,43 +146,11 @@ async function setupAndRun() {
     }
   }
 
-  /**
-   * At this point, commander arguments are not parsed yet because we need to
-   * add all the commands and their options. That's why we resort to using
-   * minimist for parsing some global options.
-   */
-  const options = minimist(process.argv.slice(2));
-
-  const root = options.projectRoot
-    ? path.resolve(options.projectRoot)
-    : process.cwd();
-
-  const reactNativePath = options.reactNativePath
-    ? path.resolve(options.reactNativePath)
-    : (() => {
-        try {
-          return path.dirname(
-            // $FlowIssue: Wrong `require.resolve` type definition
-            require.resolve('react-native/package.json', {
-              paths: [root],
-            }),
-          );
-        } catch (_ignored) {
-          throw new Error(
-            'Unable to find React Native files. Make sure "react-native" module is installed in your project dependencies.',
-          );
-        }
-      })();
-
-  const ctx = {
-    ...getLegacyConfig(root),
-    reactNativePath,
-    root,
-  };
+  const ctx = loadConfig();
 
   setProjectDir(ctx.root);
 
-  const commands = getCommands(ctx.root);
+  const commands = getCommands(ctx);
 
   commands.forEach(command => addCommand(command, ctx));
 

packages/cli/src/commands/config/config.js

@@ -0,0 +1,11 @@
+/**
+ * @flow
+ */
+import {type ContextT} from '../../tools/types.flow';
+export default {
+  name: 'config',
+  description: 'Print CLI configuration',
+  func: async (argv: string[], ctx: ContextT) => {
+    console.log(JSON.stringify(ctx, null, 2));
+  },
+};

packages/cli/src/commands/index.js

@@ -4,7 +4,6 @@
 
 import path from 'path';
 
-import findPlugins from '../tools/findPlugins';
 import logger from '../tools/logger';
 
 import type {
@@ -13,6 +12,8 @@ import type {
   LocalCommandT,
 } from '../tools/types.flow';
 
+import {type ContextT} from '../tools/types.flow';
+
 import server from './server/server';
 import runIOS from './runIOS/runIOS';
 import runAndroid from './runAndroid/runAndroid';
@@ -27,6 +28,7 @@ import upgrade from './upgrade/upgrade';
 import logAndroid from './logAndroid/logAndroid';
 import logIOS from './logIOS/logIOS';
 import info from './info/info';
+import config from './config/config';
 
 /**
  * List of built-in commands
@@ -47,6 +49,7 @@ const loadLocalCommands: Array<LocalCommandT> = [
   logAndroid,
   logIOS,
   info,
+  config,
 ];
 
 /**
@@ -55,10 +58,11 @@ const loadLocalCommands: Array<LocalCommandT> = [
  * This checks all CLI plugins for presence of 3rd party packages that define commands
  * and loads them
  */
-const loadProjectCommands = (root: string): Array<ProjectCommandT> => {
-  const plugins = findPlugins(root);
-
-  return plugins.commands.reduce((acc: Array<CommandT>, pathToCommands) => {
+const loadProjectCommands = ({
+  root,
+  commands,
+}: ContextT): Array<ProjectCommandT> => {
+  return commands.reduce((acc: Array<ProjectCommandT>, cmdPath: string) => {
     /**
      * `pathToCommand` is a path to a file where commands are defined, relative to `node_modules`
      * folder.
@@ -67,12 +71,12 @@ const loadProjectCommands = (root: string): Array<ProjectCommandT> => {
      * into consideration.
      */
     const name =
-      pathToCommands[0] === '@'
-        ? pathToCommands
+      cmdPath[0] === '@'
+        ? cmdPath
             .split(path.sep)
             .slice(0, 2)
             .join(path.sep)
-        : pathToCommands.split(path.sep)[0];
+        : cmdPath.split(path.sep)[0];
 
     const pkg = require(path.join(root, 'node_modules', name, 'package.json'));
 
@@ -81,7 +85,7 @@ const loadProjectCommands = (root: string): Array<ProjectCommandT> => {
       | Array<ProjectCommandT> = require(path.join(
       root,
       'node_modules',
-      pathToCommands,
+      cmdPath,
     ));
 
     if (Array.isArray(requiredCommands)) {
@@ -90,14 +94,14 @@ const loadProjectCommands = (root: string): Array<ProjectCommandT> => {
       );
     }
 
-    return acc.concat({...requiredCommands});
+    return acc.concat({...requiredCommands, pkg});
   }, []);
 };
 
 /**
  * Loads all the commands inside a given `root` folder
  */
-export function getCommands(root: string): Array<CommandT> {
+export function getCommands(ctx: ContextT): Array<CommandT> {
   return [
     ...loadLocalCommands,
     {
@@ -111,6 +115,6 @@ export function getCommands(root: string): Array<CommandT> {
         );
       },
     },
-    ...loadProjectCommands(root),
+    ...loadProjectCommands(ctx),
   ];
 }

packages/cli/src/commands/info/__tests__/info.test.js

@@ -8,7 +8,17 @@ jest.mock('../../../tools/logger', () => ({
   log: jest.fn(),
 }));
 
-const ctx = {reactNativePath: '', root: ''};
+const ctx = {
+  root: '',
+  reactNativePath: '',
+  dependencies: {},
+  platforms: {},
+  commands: [],
+  haste: {
+    platforms: [],
+    providesModuleNodeModules: [],
+  },
+};
 
 beforeEach(() => {
   jest.resetAllMocks();

packages/cli/src/commands/link/getDependencyConfig.js

@@ -28,6 +28,7 @@ export default function getDependencyConfig(
     Object.keys(availablePlatforms).forEach(platform => {
       platformConfigs[platform] = availablePlatforms[platform].dependencyConfig(
         folder,
+        // $FlowIssue: Flow can't match platform config with its appropriate config function
         config[platform] || {},
       );
     });

packages/cli/src/commands/link/getProjectConfig.js

@@ -24,6 +24,7 @@ export default function getProjectConfig(
     logger.debug(`Getting project config for ${getPlatformName(platform)}...`);
     platformConfigs[platform] = availablePlatforms[platform].projectConfig(
       ctx.root,
+      // $FlowIssue: Flow can't match platform config with its appropriate config function
       config[platform] || {},
     );
   });

packages/cli/src/commands/link/linkAll.js

@@ -33,19 +33,19 @@ function linkAll(
 
   const projectAssets = getAssets(context.root);
   const dependencies = getProjectDependencies(context.root);
-  const depenendenciesConfig = dependencies.map(dependnecy =>
-    getDependencyConfig(context, platforms, dependnecy),
+  const dependenciesConfig = dependencies.map(dependency =>
+    getDependencyConfig(context, platforms, dependency),
   );
 
   const assets = dedupeAssets(
-    depenendenciesConfig.reduce(
+    dependenciesConfig.reduce(
       (acc, dependency) => acc.concat(dependency.assets),
       projectAssets,
     ),
   );
 
   const tasks = flatten(
-    depenendenciesConfig.map(config => [
+    dependenciesConfig.map(config => [
       () => promisify(config.commands.prelink || commandStub),
       () => linkDependency(platforms, project, config),
       () => promisify(config.commands.postlink || commandStub),

packages/cli/src/commands/upgrade/__tests__/upgrade.test.js

@@ -55,6 +55,13 @@ const olderVersion = '0.56.0';
 const ctx = {
   root: '/project/root',
   reactNativePath: '',
+  commands: [],
+  platforms: {},
+  dependencies: {},
+  haste: {
+    providesModuleNodeModules: [],
+    platforms: [],
+  },
 };
 const opts = {
   legacy: false,