if author_time > one_month_ago:
                last_month_commenters[author_name] += 1
            if author_time > three_months_ago:
                three_months_commenters[author_name] += 1
            if author_time > six_months_ago:
                six_months_commenters[author_name] += 1
            if author_time > one_year_ago:
                one_year_commenters[author_name] += 1

	if err := DB.Migrator().AutoMigrate(&HNPost{}, &EngadgetPost{}); err != nil {
		t.Fatalf("failed to auto migrate, got error: %v", err)
	}

	for _, name := range []string{"author_id", "author_name", "author_email"} {
		if !DB.Migrator().HasColumn(&EngadgetPost{}, name) {
			t.Errorf("should has prefixed column %v", name)
		}
	}

	stmt := gorm.Statement{DB: DB}