Unidirectional current and bi-directional voltage device
It sounds like you're talking about an "ideal current source", which is more of a theoretical construct, rarely found in physical circuits. Most current sources used in practice can't tolerate a reversal in voltage; they're designed to either supply power to the circuit or absorb power from the circuit, but not both.

But an ideal source must do both, functioning as either a power source or a power sink, depending on the polarity of the voltage. If the current arrow points to the positive terminal, then it's supplying power to the circuit. If the arrow points to the negative terminal, then it's absorbing power from the circuit.