code: func Exactlyf(t TestingT, expected interface{}, actual interface{}, msg string, args ...interface{}) bool {
  	if h, ok := t.(tHelper); ok {
  		h.Helper()
  	}
  	return Exactly(t, expected, actual, append([]interface{}{msg}, args...)...)
  }
docs: // Exactlyf asserts that two objects are equal in value and type.
  //
  //    assert.Exactlyf(t, int32(123, "error message %s", "formatted"), int64(123))