Support PostgreSQL specific column types when using `change_table`.

Closes #9480.

We use `TableDefinition` for `#create_table` and `Table` for `#change_table`.
The PostgreSQL sepcifc types were only defined on `TableDefinition` so I
also added them to `Table`.

1 files changed, 15 insertions, 0 deletions

diff --git a/activerecord/test/cases/adapters/postgresql/json_test.rb b/activerecord/test/cases/adapters/postgresql/json_test.rb
index d64037eec0..6fc08ae4f0 100644
--- a/activerecord/test/cases/adapters/postgresql/json_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/json_test.rb
@@ -31,6 +31,21 @@ class PostgresqlJSONTest < ActiveRecord::TestCase
     assert_equal :json, @column.type
   end
 
+  def test_change_table_supports_json
+    @connection.transaction do
+      @connection.change_table('json_data_type') do |t|
+        t.json 'users', default: '{}'
+      end
+      JsonDataType.reset_column_information
+      column = JsonDataType.columns.find { |c| c.name == 'users' }
+      assert_equal :json, column.type
+
+      raise ActiveRecord::Rollback # reset the schema change
+    end
+  ensure
+    JsonDataType.reset_column_information
+  end
+
   def test_type_cast_json
     assert @column