Prevent warnings if a generator tries to run

[DEPRECATED] This Gemfile does not include an explicit global source. Not using an explicit global source may result in a different lockfile being generated depending on the gems you have installed locally before bundler is run. Instead, define a global source in your Gemfile like this: source "https://rubygems.org".

test/generators/suspenders/install/web_generator_test.rb

@@ -52,6 +52,10 @@ class WebGeneratorTest < Rails::Generators::TestCase
 
         def prepare_destination
           touch "Gemfile"
+
+          File.open("test/dummy/Gemfile", "w") do |f|
+            f.write('source "https://rubygems.org"')
+          end
         end
 
         def restore_destination