From 0d38532a8aadb81e728f271a3cfe3dbdd273f174 Mon Sep 17 00:00:00 2001
From: Artem Butusov <butusova@amazon.com>
Date: Sat, 30 Mar 2019 12:58:55 -0400
Subject: [PATCH] Added dedupe option to prevent bundling the same package
 multiple times

---
 .gitignore                                    |  1 +
 README.md                                     |  5 ++++
 index.d.ts                                    |  6 ++++
 src/index.js                                  |  7 ++++-
 test/node_modules/react-consumer/index.js     |  3 ++
 .../react-consumer/node_modules/.gitkeep      |  0
 .../node_modules/react/index.js               |  1 +
 test/node_modules/react/index.js              |  1 +
 test/samples/react-app/main.js                |  4 +++
 test/test.js                                  | 30 +++++++++++++++++++
 10 files changed, 57 insertions(+), 1 deletion(-)
 create mode 100644 test/node_modules/react-consumer/index.js
 create mode 100644 test/node_modules/react-consumer/node_modules/.gitkeep
 create mode 100644 test/node_modules/react-consumer/node_modules/react/index.js
 create mode 100644 test/node_modules/react/index.js
 create mode 100644 test/samples/react-app/main.js

diff --git a/.gitignore b/.gitignore
index 08625d3..7bb0182 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@ node_modules
 dist
 .gobble*
 !test/node_modules
+!test/node_modules/react-consumer/node_modules
diff --git a/README.md b/README.md
index 75878b0..b419aa5 100644
--- a/README.md
+++ b/README.md
@@ -65,6 +65,11 @@ export default {
       // ES2015 modules
       modulesOnly: true, // Default: false
 
+      // Force resolving for these modules to root's node_modules that helps
+      // to prevent bundling the same package multiple times if package is
+      // imported from dependencies.
+      dedupe: [ 'react', 'react-dom' ], // Default: []
+
       // Any additional options that should be passed through
       // to node-resolve
       customResolveOptions: {
diff --git a/index.d.ts b/index.d.ts
index b1d3faa..adc18bd 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -60,6 +60,12 @@ interface RollupNodeResolveOptions {
 	 * @default false
 	 */
 	modulesOnly?: boolean;
+	/**
+	 * Force resolving for these modules to root's node_modules that helps
+	 * to prevent bundling the same package multiple times if package is
+	 * imported from dependencies.
+	 */
+	dedupe?: string[];
 	/**
 	 * Any additional options that should be passed through
 	 * to node-resolve
diff --git a/src/index.js b/src/index.js
index 6dc093e..6e5a4a2 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,4 +1,4 @@
-import {dirname, extname, normalize, resolve, sep} from 'path';
+import {dirname, extname, normalize, resolve, sep, join} from 'path';
 import builtins from 'builtin-modules';
 import resolveId from 'resolve';
 import isModule from 'is-module';
@@ -40,6 +40,7 @@ function cachedIsFile (file, cb) {
 const resolveIdAsync = (file, opts) => new Promise((fulfil, reject) => resolveId(file, opts, (err, contents) => err ? reject(err) : fulfil(contents)));
 
 export default function nodeResolve ( options = {} ) {
+	const dedupe = options.dedupe || [];
 	const useModule = options.module !== false;
 	const useMain = options.main !== false;
 	const useJsnext = options.jsnext === true;
@@ -82,6 +83,10 @@ export default function nodeResolve ( options = {} ) {
 
 			const basedir = importer ? dirname( importer ) : process.cwd();
 
+			if (dedupe.indexOf(importee) !== -1) {
+				importee = join(process.cwd(), 'node_modules', importee);
+			}
+
 			// https://github.com/defunctzombie/package-browser-field-spec
 			if (options.browser && browserMapCache[importer]) {
 				const resolvedImportee = resolve( basedir, importee );
diff --git a/test/node_modules/react-consumer/index.js b/test/node_modules/react-consumer/index.js
new file mode 100644
index 0000000..bfc70f0
--- /dev/null
+++ b/test/node_modules/react-consumer/index.js
@@ -0,0 +1,3 @@
+import React from 'react'
+
+export default 'react-consumer:' + React
diff --git a/test/node_modules/react-consumer/node_modules/.gitkeep b/test/node_modules/react-consumer/node_modules/.gitkeep
new file mode 100644
index 0000000..e69de29
diff --git a/test/node_modules/react-consumer/node_modules/react/index.js b/test/node_modules/react-consumer/node_modules/react/index.js
new file mode 100644
index 0000000..8bfd7ab
--- /dev/null
+++ b/test/node_modules/react-consumer/node_modules/react/index.js
@@ -0,0 +1 @@
+export default 'react:child'
\ No newline at end of file
diff --git a/test/node_modules/react/index.js b/test/node_modules/react/index.js
new file mode 100644
index 0000000..6fd06a9
--- /dev/null
+++ b/test/node_modules/react/index.js
@@ -0,0 +1 @@
+export default 'react:root'
diff --git a/test/samples/react-app/main.js b/test/samples/react-app/main.js
new file mode 100644
index 0000000..1b39a2a
--- /dev/null
+++ b/test/samples/react-app/main.js
@@ -0,0 +1,4 @@
+import React from 'react'
+import ReactConsumer from 'react-consumer'
+
+export { React, ReactConsumer }
diff --git a/test/test.js b/test/test.js
index 75baa96..09b4cda 100644
--- a/test/test.js
+++ b/test/test.js
@@ -761,4 +761,34 @@ describe( 'rollup-plugin-node-resolve', function () {
 		});
 	});
 
+	it( 'single module version is bundle if dedupe is set', () => {
+		return rollup.rollup({
+			input: 'samples/react-app/main.js',
+			plugins: [
+				nodeResolve({
+					dedupe: [ 'react' ]
+				})
+			]
+		}).then( executeBundle ).then( module => {
+			assert.deepEqual(module.exports, { 
+				React: 'react:root',
+				ReactConsumer: 'react-consumer:react:root'
+			});
+		});
+	});
+
+	it( 'multiple module versions are bundled if dedupe is not set', () => {
+		return rollup.rollup({
+			input: 'samples/react-app/main.js',
+			plugins: [
+				nodeResolve()
+			]
+		}).then( executeBundle ).then( module => {
+			assert.deepEqual(module.exports, { 
+				React: 'react:root',
+				ReactConsumer: 'react-consumer:react:child'
+			});
+		});
+	});
+
 });