From 6010bdd416503e6c47549369682574a0f9fe1ba0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=BE=99=E8=85=BE=E9=81=93?= <LongTengDao@LongTengDao.com>
Date: Mon, 4 Mar 2019 15:41:22 +0800
Subject: [PATCH] fix: the empty string importee should not always be treated
 as external module id (#2733)

* Update mergeOptions.ts

* Add test for using empty string as virtual module name
---
 src/utils/mergeOptions.ts                         |  2 +-
 .../empty-string-as-module-name/_config.js        | 15 +++++++++++++++
 .../samples/empty-string-as-module-name/main.js   |  2 ++
 .../empty-string-as-module-name/main.js#.js       |  1 +
 4 files changed, 19 insertions(+), 1 deletion(-)
 create mode 100644 test/function/samples/empty-string-as-module-name/_config.js
 create mode 100644 test/function/samples/empty-string-as-module-name/main.js
 create mode 100644 test/function/samples/empty-string-as-module-name/main.js#.js

diff --git a/src/utils/mergeOptions.ts b/src/utils/mergeOptions.ts
index f2f86f76e61..8f8c2629a98 100644
--- a/src/utils/mergeOptions.ts
+++ b/src/utils/mergeOptions.ts
@@ -168,7 +168,7 @@ function addUnknownOptionErrors(
 
 function getCommandOptions(rawCommandOptions: GenericConfigObject): GenericConfigObject {
 	const command = { ...rawCommandOptions };
-	command.external = (rawCommandOptions.external || '').split(',');
+	command.external = rawCommandOptions.external ? rawCommandOptions.external.split(',') : [];
 
 	if (rawCommandOptions.globals) {
 		command.globals = Object.create(null);
diff --git a/test/function/samples/empty-string-as-module-name/_config.js b/test/function/samples/empty-string-as-module-name/_config.js
new file mode 100644
index 00000000000..dfbc2595b37
--- /dev/null
+++ b/test/function/samples/empty-string-as-module-name/_config.js
@@ -0,0 +1,15 @@
+module.exports = {
+	description: 'allows using empty string as a valid module name',
+	options: {
+		external: () => false,
+		plugins: [
+			{
+				resolveId(importee, importer) {
+					if (importee === '') {
+						return importer + '#.js';
+					}
+				}
+			}
+		]
+	}
+};
diff --git a/test/function/samples/empty-string-as-module-name/main.js b/test/function/samples/empty-string-as-module-name/main.js
new file mode 100644
index 00000000000..29634821528
--- /dev/null
+++ b/test/function/samples/empty-string-as-module-name/main.js
@@ -0,0 +1,2 @@
+import { importee } from '';
+assert.strictEqual(importee, 'xxx');
diff --git a/test/function/samples/empty-string-as-module-name/main.js#.js b/test/function/samples/empty-string-as-module-name/main.js#.js
new file mode 100644
index 00000000000..221b08850db
--- /dev/null
+++ b/test/function/samples/empty-string-as-module-name/main.js#.js
@@ -0,0 +1 @@
+export var importee = 'xxx';