FIX: allow staff members to send PMs when enable_private_messages is disabled

lib/guardian.rb

@@ -279,9 +279,7 @@ class Guardian
     # Have to be a basic level at least
     @user.has_trust_level?(SiteSetting.min_trust_to_send_messages) &&
     # PMs are enabled
-    (SiteSetting.enable_private_messages ||
-      @user.username == SiteSetting.site_contact_username ||
-      @user == Discourse.system_user) &&
+    (is_staff? || SiteSetting.enable_private_messages) &&
     # Can't send PMs to suspended users
     (is_staff? || target.is_a?(Group) || !target.suspended?) &&
     # Blocked users can only send PM to staff

spec/components/guardian_spec.rb

@@ -168,14 +168,13 @@ describe Guardian do
     context "enable_private_messages is false" do
       before { SiteSetting.enable_private_messages = false }
 
-      it "returns false if user is not the contact user" do
-        expect(Guardian.new(user).can_send_private_message?(another_user)).to be_falsey
+      it "returns false if user is not staff member" do
+        expect(Guardian.new(trust_level_4).can_send_private_message?(another_user)).to be_falsey
       end
 
-      it "returns true for the contact user and system user" do
-        SiteSetting.site_contact_username = user.username
-        expect(Guardian.new(user).can_send_private_message?(another_user)).to be_truthy
-        expect(Guardian.new(Discourse.system_user).can_send_private_message?(another_user)).to be_truthy
+      it "returns true for staff member" do
+        expect(Guardian.new(moderator).can_send_private_message?(another_user)).to be_truthy
+        expect(Guardian.new(admin).can_send_private_message?(another_user)).to be_truthy
       end
     end