func TestMain(m *testing.M) {
	testdbs.InitDBS()
	// main block that runs tests
	code := m.Run()
	err := testdbs.Clean()
	if err != nil {
		os.Exit(1)
	}
	os.Exit(code)
}

And then in your tests you can iterate over the DBs

func TestMyFunction(t *testing.T) {
    for _, db := range testdbs.DBs() {
        t.Run(dbt.DbType(), func(t *testing.T) {
            db := dbt.Conn()
            // db is *gorm.DB
		})
	}
}

if you need to isolate DBs, e.g. run multiple tests on the same db/table you can use ConnDbName("custom") to crete a new database wit the passed name.

note: connections will be reused cross tests for every db name

func TestMyFunction(t *testing.T) {
    for _, db := range testdbs.DBs() {
        t.Run(dbt.DbType(), func(t *testing.T) {
            db := dbt.ConnDbName("custom")
            // db is *gorm.DB
		})
	}
}

running tests

As a default calling go test will only start an embedded sqlite on a temp directory, to run the tests with all the supported DBs you need to call go test -alldbs