Add predicate for when on GitLab.com and not JiHu

For things which are highly specific to GitLab.com, we may want to
exclude JiHu. This adds a `com_except_jh?` method to check for when the
instance is GitLab.com but not JiHu.

ee/lib/gitlab/com.rb

@@ -10,7 +10,7 @@ module Com
     def self.gitlab_com_group_member?(user)
       return false unless user.is_a?(::User)
 
-      Gitlab.com? && gitlab_com_user_ids.include?(user.id)
+      Gitlab.com_except_jh? && gitlab_com_user_ids.include?(user.id)
     end
 
     # rubocop: disable CodeReuse/ActiveRecord
@@ -18,7 +18,6 @@ def self.gitlab_com_user_ids
       l1_cache_backend.fetch(ALLOWED_USER_IDS_KEY, expires_in: EXPIRY_TIME_L1_CACHE) do
         l2_cache_backend.fetch(ALLOWED_USER_IDS_KEY, expires_in: EXPIRY_TIME_L2_CACHE) do
           group = Group.find_by(path: GITLAB_COM_GROUP, parent_id: nil)
-
           if group
             group.members.pluck_user_ids.to_set
           else

ee/spec/lib/gitlab/com_spec.rb

@@ -13,6 +13,7 @@
 
     before do
       allow(Gitlab).to receive(:com?).and_return(true)
+      allow(Gitlab).to receive(:jh?).and_return(false)
     end
 
     context 'when user is a gitlab team member' do
@@ -27,6 +28,22 @@
 
         it_behaves_like 'allowed user IDs are cached'
       end
+
+      context 'when not on Gitlab.com' do
+        before do
+          allow(Gitlab).to receive(:com?).and_return(false)
+        end
+
+        it { is_expected.to be false }
+      end
+
+      context 'when on JiHu' do
+        before do
+          allow(Gitlab).to receive(:jh?).and_return(true)
+        end
+
+        it { is_expected.to be false }
+      end
     end
 
     context 'when user is not a gitlab team member' do

lib/gitlab.rb

@@ -60,6 +60,10 @@ def self.com?
     simulate_com? || Gitlab.config.gitlab.url == Gitlab::Saas.com_url || gl_subdomain?
   end
 
+  def self.com_except_jh?
+    com? && !jh?
+  end
+
   def self.com
     yield if com?
   end

spec/lib/gitlab_spec.rb

@@ -132,6 +132,28 @@
     end
   end
 
+  describe '.com_except_jh?' do
+    subject { described_class.com_except_jh? }
+
+    before do
+      allow(described_class).to receive(:com?).and_return(com?)
+      allow(described_class).to receive(:jh?).and_return(jh?)
+    end
+
+    using RSpec::Parameterized::TableSyntax
+
+    where(:com?, :jh?, :expected) do
+      true  | true  | false
+      true  | false | true
+      false | true  | false
+      false | false | false
+    end
+
+    with_them do
+      it { is_expected.to eq(expected) }
+    end
+  end
+
   describe '.com' do
     subject { described_class.com { true } }