Fail on export all dup optionally

src/Bundle.js

@@ -26,6 +26,8 @@ export default class Bundle {
 			});
 		}
 
+		this.failOnExportAllDup = Boolean( options.failOnExportAllDup );
+
 		this.plugins = ensureArray( options.plugins );
 
 		this.plugins.forEach( plugin => {
@@ -211,6 +213,9 @@ export default class Bundle {
 				this.moduleById.set( id, module );
 
 				return this.fetchAllDependencies( module ).then( () => {
+					if ( !this.failOnExportAllDup ) {
+						return module;
+					}
 					module.exportsAll = blank();
 					keys( module.exports ).forEach( name => {
 						module.exportsAll[name] = module.id;

src/rollup.js

@@ -31,7 +31,8 @@ const ALLOWED_KEYS = [
 	'sourceMapFile',
 	'targets',
 	'treeshake',
-	'useStrict'
+	'useStrict',
+	'failOnExportAllDup'
 ];
 
 export function rollup ( options ) {

test/function/double-named-export-from/_config.js

@@ -7,6 +7,9 @@ function normalize( file ) {
 
 module.exports = {
 	description: 'throws on duplicate export * from',
+	options: {
+		failOnExportAllDup: true
+	},
 	error: err => {
 		assert.equal( err.message, `A module cannot have multiple exports with the same name ('foo')` +
 			` from ${normalize( 'foo.js' )} and ${normalize( 'deep.js' )}` );

test/test.js

@@ -76,7 +76,7 @@ describe( 'rollup', function () {
 			return rollup.rollup({ entry: 'x', plUgins: [] }).then( function () {
 				throw new Error( 'Missing expected error' );
 			}, function ( err ) {
-				assert.equal( err.message, 'Unexpected key \'plUgins\' found, expected one of: acorn, banner, cache, dest, entry, exports, external, footer, format, globals, indent, intro, moduleId, moduleName, noConflict, onwarn, outro, plugins, preferConst, sourceMap, sourceMapFile, targets, treeshake, useStrict' );
+				assert.equal( err.message, 'Unexpected key \'plUgins\' found, expected one of: acorn, banner, cache, dest, entry, exports, external, footer, format, globals, indent, intro, moduleId, moduleName, noConflict, onwarn, outro, plugins, preferConst, sourceMap, sourceMapFile, targets, treeshake, useStrict, failOnExportAllDup' );
 			});
 		});
 	});