undo non-string ID change (#692)

src/Bundle.js

@@ -198,9 +198,6 @@ export default class Bundle {
 		return mapSequence( module.sources, source => {
 			return this.resolveId( source, module.id )
 				.then( resolvedId => {
-					module.resolvedIds[ source ] = resolvedId;
-
-					if ( !resolvedId || typeof resolvedId === 'string' ) {
 					let externalName;
 					if ( resolvedId ) {
 						// If the `resolvedId` is supposed to be external, make it so.
@@ -209,7 +206,6 @@ export default class Bundle {
 						// This could be an external, relative dependency, based on the current module's parent dir.
 						externalName = resolve( module.id, '..', source );
 					}
-
 					const forcedExternal = externalName && this.isExternal( externalName );
 
 					if ( !resolvedId || forcedExternal ) {
@@ -226,8 +222,6 @@ export default class Bundle {
 								normalizedExternal = resolvedId;
 							}
 						}
-
-							// overwrite existing
 						module.resolvedIds[ source ] = normalizedExternal;
 
 						if ( !this.moduleById.has( normalizedExternal ) ) {
@@ -235,16 +229,16 @@ export default class Bundle {
 							this.externalModules.push( module );
 							this.moduleById.set( normalizedExternal, module );
 						}
-
-							return null;
-						}
 					}
 
+					else {
 						if ( resolvedId === module.id ) {
 							throw new Error( `A module cannot import itself (${resolvedId})` );
 						}
 
+						module.resolvedIds[ source ] = resolvedId;
 						return this.fetchModule( resolvedId, module.id );
+					}
 				});
 		});
 	}

src/Module.js

@@ -191,16 +191,12 @@ export default class Module {
 	}
 
 	basename () {
-		if ( typeof this.id === 'string' ) {
 		const base = basename( this.id );
 		const ext = extname( this.id );
 
 		return makeLegalIdentifier( ext ? base.slice( 0, -ext.length ) : base );
 	}
 
-		return 'module';
-	}
-
 	bindAliases () {
 		keys( this.declarations ).forEach( name => {
 			if ( name === '*' ) return;

test/function/custom-resolver-non-string/_config.js

@@ -1,15 +0,0 @@
-const FOO = {};
-
-module.exports = {
-	description: 'allows resolveId to return a non-string',
-	options: {
-		plugins: [{
-			resolveId: importee => {
-				if ( importee === 'foo' ) return FOO;
-			},
-			load: id => {
-				if ( id === FOO ) return 'export default 42';
-			}
-		}]
-	}
-};

test/function/custom-resolver-non-string/main.js

@@ -1,2 +0,0 @@
-import foo from 'foo';
-assert.equal( foo, 42 );