Raise ArgumentError if limit and lock are used for Oracle12 visitor

it would generates `SELECT ... FETCH FIRST n ROWS ONLY FOR UPDATE`
which causes Oracle 12c database returns this error :

ORA-02014: cannot select FOR UPDATE from view with DISTINCT, GROUP BY, etc.

1 files changed, 4 insertions, 3 deletions

diff --git a/test/visitors/test_oracle12.rb b/test/visitors/test_oracle12.rb
index df0f01b30b..3263007ddb 100644
--- a/test/visitors/test_oracle12.rb
+++ b/test/visitors/test_oracle12.rb
@@ -29,12 +29,13 @@ module Arel
       end
 
       describe 'locking' do
-        it 'removes limit when locking' do
+        it 'generates ArgumentError if limit and lock are used' do
           stmt = Nodes::SelectStatement.new
           stmt.limit = Nodes::Limit.new(10)
           stmt.lock = Nodes::Lock.new(Arel.sql('FOR UPDATE'))
-          sql = compile(stmt)
-          sql.must_be_like "SELECT FOR UPDATE"
+          assert_raises ArgumentError do
+            sql = compile(stmt)
+          end
         end
 
         it 'defaults to FOR UPDATE when locking' do