Migrations will raise an exception if there are multiple column definitions (same name).

1 files changed, 11 insertions, 0 deletions

diff --git a/activerecord/test/cases/migration/change_schema_test.rb b/activerecord/test/cases/migration/change_schema_test.rb
index f4d16cb093..7777508349 100644
--- a/activerecord/test/cases/migration/change_schema_test.rb
+++ b/activerecord/test/cases/migration/change_schema_test.rb
@@ -196,6 +196,17 @@ module ActiveRecord
         assert_equal "you can't redefine the primary key column 'testing_id'. To define a custom primary key, pass { id: false } to create_table.", error.message
       end
 
+      def test_create_table_raises_when_defining_existing_column
+        error = assert_raise(ArgumentError) do
+          connection.create_table :testings do |t|
+            t.column :testing_column, :string
+            t.column :testing_column, :integer
+          end
+        end
+
+        assert_equal "you can't define an already defined column 'testing_column'.", error.message
+      end
+
       def test_create_table_with_timestamps_should_create_datetime_columns
         connection.create_table table_name do |t|
           t.timestamps