Add a minifier path option to the ModuleGraph path

Reviewed By: mjesun

Differential Revision: D6998189

fbshipit-source-id: 4876de98b9970088161d78e1b462688307ef477f

packages/metro/src/ModuleGraph/worker/__tests__/optimize-module-test.js

@@ -22,12 +22,15 @@ const {SourceMapConsumer} = require('source-map');
 
 const {objectContaining} = jasmine;
 
+const METRO_MINIFIER = 'metro-minify-uglify';
+
 describe('optimizing JS modules', () => {
   const filename = 'arbitrary/file.js';
   const sourceExts = new Set(['js', 'json']);
   const asyncRequireModulePath = 'asyncRequire';
   const optimizationOptions = {
     dev: false,
+    minifierPath: METRO_MINIFIER,
     platform: 'android',
     postMinifyProcess: x => x,
   };
@@ -144,6 +147,7 @@ describe('optimizing JS modules', () => {
       optimizeModule(new Buffer(JSON.stringify(data), 'utf8'), {
         dev: true,
         platform: '',
+        minifierPath: METRO_MINIFIER,
         postMinifyProcess: ({code, map}) => ({code, map}),
       }),
     ).toEqual(data);

packages/metro/src/ModuleGraph/worker/optimize-module.js

@@ -13,9 +13,9 @@
 const constantFolding = require('../../JSTransformer/worker/constant-folding')
   .plugin;
 const generate = require('./generate');
+const getMinifier = require('../../lib/getMinifier');
 const inline = require('../../JSTransformer/worker/inline').plugin;
 const invariant = require('fbjs/lib/invariant');
-const minify = require('metro-minify-uglify');
 const optimizeDependencies = require('./optimizeDependencies');
 const sourceMap = require('source-map');
 
@@ -25,10 +25,12 @@ import type {TransformedSourceFile, TransformResult} from '../types.flow';
 import type {BabelSourceMap} from '@babel/core';
 import type {MetroSourceMap} from 'metro-source-map';
 import type {PostMinifyProcess} from '../../Bundler/index.js';
+import type {TransformResult as BabelTransformResult} from '@babel/core';
 
 export type OptimizationOptions = {|
   dev: boolean,
   isPolyfill?: boolean,
+  minifierPath: string,
   platform: string,
   postMinifyProcess: PostMinifyProcess,
 |};
@@ -93,6 +95,7 @@ function optimize(
   const inputMap = transformed.map;
   const gen = generate(optimized.ast, file, '', true);
 
+  const minify = getMinifier(options.minifierPath);
   const min = minify.withSourceMap(
     gen.code,
     inputMap && gen.map && mergeSourceMaps(file, inputMap, gen.map),
@@ -106,7 +109,12 @@ function optimize(
   };
 }
 
-function optimizeCode(code, map, filename, inliningOptions) {
+function optimizeCode(
+  code,
+  map,
+  filename,
+  inliningOptions,
+): BabelTransformResult {
   return transformSync(code, {
     plugins: [
       [constantFolding],

packages/metro/src/lib/getMinifier.js

@@ -0,0 +1,32 @@
+/**
+ * Copyright (c) 2018-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ * @format
+ */
+
+'use strict';
+
+import type {MetroMinifier} from 'metro-minify-uglify';
+
+function getMinifier(minifierPath: string): MetroMinifier {
+  // Note: minifierPath should be an absolute path OR a module name here!
+  // The options allow relative paths but they HAVE to be normalized at
+  // any entry point that accepts them...
+  try {
+    // $FlowFixMe TODO t0 cannot do require with literal
+    return require(minifierPath);
+  } catch (e) {
+    throw new Error(
+      'A problem occurred while trying to fetch the minifier. Path: "' +
+        minifierPath +
+        '", error message: ' +
+        e.message,
+    );
+  }
+}
+
+module.exports = getMinifier;