Add support for count

Author: kou

lib/activerecord_adbc_adapter/result.rb

@@ -92,6 +92,15 @@ def indexed_rows
       @indexed_rows ||= to_a
     end
 
+    def cast_values(type_overrides = {})
+      # TODO: type_overrides support
+      if fields.size == 1
+        rows.map(&:first)
+      else
+        rows
+      end
+    end
+
     def to_arrow
       @table
     end

test/test_model.rb

@@ -23,6 +23,10 @@ def test_all
                  User.select(:id).all)
   end
 
+  def test_count
+    assert_equal(3, User.count)
+  end
+
   sub_test_case(".ingest") do
     def id_array
       Arrow::Int64Array.new([4, 5, 6])