[rubygems/rubygems] Use a local temporary directory

To make tests more deterministic, since `Dir.tmpdir` sometimes will
return the current directory dependending on the writability of other
paths, and in that case since the current directory is changed by our
tests, tests can fail.

Force a local tmp folder instead, which will always be writable.

https://github.com/rubygems/rubygems/commit/3e522bac65

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/rubygems/test_case.rb b/lib/rubygems/test_case.rb
index 651e89dd0b..6e9c50d9a5 100644
--- a/lib/rubygems/test_case.rb
+++ b/lib/rubygems/test_case.rb
@@ -300,6 +300,7 @@ class Gem::TestCase < Minitest::Test
     ENV['GEM_VENDOR'] = nil
     ENV['GEMRC'] = nil
     ENV['SOURCE_DATE_EPOCH'] = nil
+    ENV["TMPDIR"] = File.expand_path("tmp")
 
     @current_dir = Dir.pwd
     @fetcher     = nil