test_process.rb: assert minimum maxgroups

* test/ruby/test_process.rb (TestProcess#test_maxgroups):
  maxgroups should be one at least.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62519 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/ruby/test_process.rb

@@ -1522,6 +1522,7 @@ class TestProcess < Test::Unit::TestCase
   rescue NotImplementedError
   else
     assert_kind_of(Integer, max)
+    assert_predicate(max, :positive?)
     skip "not limited to NGROUPS_MAX" if /darwin/ =~ RUBY_PLATFORM
     gs = Process.groups
     assert_operator(gs.size, :<=, max)