Today I tested a number of SMD LEDs for the plant watering sensor project. I soldered all 13 LEDs I shortlisted onto a small board and connected it to an Arduino Zero Pro. So I could try the different flashing styles I planed to use more or less automatically. That way I could focus on the LED flashing itself, without being distracted by switching cables.
This is the board I made. Very simple but functional. I used red and blue male header to mark the anode and cathode of the LEDs. There is a sticker on the bottom with the LED numbers on it.
I mounted everything on a very small breadboard and did all connections to the Arduino.