From f68c10198f2a91373a8dfb90cf38aec4978428ff Mon Sep 17 00:00:00 2001
From: Igor Redchuk <redchuk@gmail.com>
Date: Tue, 18 Apr 2017 12:52:34 +0200
Subject: [PATCH] Fix bug when cannot set a config value to empty string
 (#3018)

* Fixes regression introduced in PR #2440
* Related to #2434
---
 __tests__/commands/config.js | 10 ++++++++--
 src/cli/commands/config.js   |  3 +--
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/__tests__/commands/config.js b/__tests__/commands/config.js
index 54c5db38f1..c11f043e1d 100644
--- a/__tests__/commands/config.js
+++ b/__tests__/commands/config.js
@@ -32,12 +32,18 @@ test('cache-folder flag has higher priorities than .yarnrc file', (): Promise<vo
     });
 });
 
-test('set true when option value is empty', (): Promise<void> => {
-  return runConfig(['set', 'strict-ssl', ''], {}, '', (config) => {
+test('set true when option value is undefined', (): Promise<void> => {
+  return runConfig(['set', 'strict-ssl'], {}, '', (config) => {
     expect(config.registries.yarn.homeConfig['strict-ssl']).toBe(true);
   });
 });
 
+test('set empty string to an option', (): Promise<void> => {
+  return runConfig(['set', 'version-tag-prefix', ''], {}, '', (config) => {
+    expect(config.registries.yarn.homeConfig['version-tag-prefix']).toBe('');
+  });
+});
+
 test('set value "false" to an option', (): Promise<void> => {
   return runConfig(['set', 'strict-ssl', 'false'], {}, '', (config) => {
     expect(config.registries.yarn.homeConfig['strict-ssl']).toBe(false);
diff --git a/src/cli/commands/config.js b/src/cli/commands/config.js
index f2b5c64ed9..450c6fb8fb 100644
--- a/src/cli/commands/config.js
+++ b/src/cli/commands/config.js
@@ -19,8 +19,7 @@ export const {run, setFlags} = buildSubCommands('config', {
     if (args.length === 0 || args.length > 2) {
       return false;
     }
-    const key = args[0];
-    const val = args[1] || true;
+    const [key, val = true] = args;
     const yarnConfig = config.registries.yarn;
     await yarnConfig.saveHomeConfig({[key]: val});
     reporter.success(reporter.lang('configSet', key, val));