How to use the keycode.codes.down function in keycode

await waitForDom(() => {
                    const input = select('NATIVE_INPUT_NUMBER');

                    simulate.keyDown(input, {keyCode: KeyCodes.down});

                    assertCommit(input, onChange, value - step);
                });
            });

await waitForDom(() => {
                    const input = select('NATIVE_INPUT_NUMBER');

                    simulate.keyDown(input, {keyCode: KeyCodes.down});

                    expect(onChange).not.to.have.been.called;
                    expect(input).to.have.value(String(value));
                });
            });

public pressDownKey(opts?: Modifiers) {
        simulate.keyDown(this.nativeInput, {keyCode: KeyCodes.down, ...opts});
    }

private handleInputKeyDown: React.KeyboardEventHandler = e => {
        switch (e.keyCode) {
            case KeyCodes.up:
                this.stepValue(Direction.Increase, e.shiftKey ? 10 : 1);
                e.preventDefault();
                break;
            case KeyCodes.down:
                this.stepValue(Direction.Decrease, e.shiftKey ? 10 : 1);
                e.preventDefault();
                break;
            case KeyCodes.enter:
                this.commit(this.state.value);
                e.preventDefault();
                break;
            case KeyCodes.esc:
                this.revert();
                e.preventDefault();
                break;
        }
    }