From a93f55569950b714a3d1235e59ad0a7d5b88f938 Mon Sep 17 00:00:00 2001
From: Takashi Kokubun <takashikkbn@gmail.com>
Date: Fri, 26 Apr 2019 18:18:09 +0900
Subject: [PATCH] tool/sync_default_gems.rb: Check prerequisites

---
 tool/sync_default_gems.rb | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tool/sync_default_gems.rb b/tool/sync_default_gems.rb
index e7917f7bec..2bef1c621c 100644
--- a/tool/sync_default_gems.rb
+++ b/tool/sync_default_gems.rb
@@ -208,6 +208,9 @@ def sync_default_gems(gem)
 end
 
 def sync_lib(repo)
+  unless File.directory?("../#{repo}")
+    abort "Expected '../#{repo}' (#{File.expand_path("../#{repo}")}) to be a directory, but it wasn't."
+  end
   `rm -rf lib/#{repo}.rb lib/#{repo}/* test/test_#{repo}.rb`
   `cp -rf ../#{repo}/lib/* lib`
   tests = if File.directory?("test/#{repo}")