Fix Rollup build regression

src/index.js

@@ -113,10 +113,15 @@ export default function commonjs ( options = {} ) {
 	}
 	function setIsCjsPromise ( id, promise ) {
 		const isCjsPromise = isCjsPromises[id];
-		if (isCjsPromise)
-			isCjsPromise.resolve(promise);
-		else
+		if (isCjsPromise) {
+			if (isCjsPromise.resolve) {
+				isCjsPromise.resolve(promise);
+				isCjsPromise.resolve = undefined;
+			}
+		}
+		else {
 			isCjsPromises[id] = { promise: promise, resolve: undefined };
+		}
 	}
 
 	return {
@@ -178,7 +183,7 @@ export default function commonjs ( options = {} ) {
 				const actualId = id.slice( PREFIX.length );
 				const name = getName( actualId );
 
-				return getIsCjsPromise( actualId )
+				return ( ( extensions.indexOf( extname( id ) ) === -1 ) ? Promise.resolve(false) : getIsCjsPromise( actualId ) )
 					.then( isCjs => {
 						if ( isCjs )
 							return `import { __moduleExports } from ${JSON.stringify( actualId )}; export default __moduleExports;`;

test/test.js

@@ -238,6 +238,32 @@ describe( 'rollup-plugin-commonjs', () => {
 			assert.equal( module.exports, 'foobar', generated.code );
 		});
 
+		it( 'handles successive builds', async () => {
+			const plugin = commonjs()
+			let bundle = await rollup({
+				input: 'samples/corejs/literal-with-default.js',
+				plugins: [ plugin ]
+			});
+			await bundle.generate({
+				format: 'cjs'
+			});
+
+			bundle = await rollup({
+				input: 'samples/corejs/literal-with-default.js',
+				plugins: [ plugin ]
+			});
+			const generated = await bundle.generate({
+				format: 'cjs'
+			});
+
+			const module = { exports: {} };
+
+			const fn = new Function ( 'module', 'exports', generated.code );
+			fn( module, module.exports );
+
+			assert.equal( module.exports, 'foobar', generated.code );
+		});
+
 		it( 'allows named exports to be added explicitly via config', async () => {
 			const bundle = await rollup({
 				input: 'samples/custom-named-exports/main.js',