Fix flaky test_latest_gc_info_need_major_by

The test could flake because a major GC could be triggered due to allocation
for caches or other things, which would cause the test to fail.

1 files changed, 7 insertions, 6 deletions

diff --git a/test/ruby/test_gc.rb b/test/ruby/test_gc.rb
index b0794c0845..7ae05e206f 100644
--- a/test/ruby/test_gc.rb
+++ b/test/ruby/test_gc.rb
@@ -356,13 +356,14 @@ class TestGc < Test::Unit::TestCase
     3.times { GC.start }
     assert_nil GC.latest_gc_info(:need_major_by)
 
-    # allocate objects until need_major_by is set or major GC happens
-    objects = []
-    while GC.latest_gc_info(:need_major_by).nil?
-      objects.append(100.times.map { '*' })
-    end
-
     EnvUtil.without_gc do
+      # allocate objects until need_major_by is set or major GC happens
+      objects = []
+      while GC.latest_gc_info(:need_major_by).nil?
+        objects.append(100.times.map { '*' })
+        GC.start(full_mark: false)
+      end
+
       # We need to ensure that no GC gets ran before the call to GC.start since
       # it would trigger a major GC. Assertions could allocate objects and
       # trigger a GC so we don't run assertions until we perform the major GC.