Recently, I was looking for a quick and easy solution to charge and measure the capacity of the Lithium batteries I have on hand.
Some are 18650 format, some are JST 2.54, some JST 1.27, etc... 
 I got 2 simple modules, one for charging based on IP2312 from Injoinic, and one module for discharge which has several name like HW-586.

https://www.aliexpress.com/item/33032500223.html
https://www.amazon.com/Wondiwe-HW-586-Battery-Capacity-Testing/dp/B08MPKC8FM

The discharging part need some external resistors to drain the current. I use 2 * 7.5 ohm with a switch to put them in parallel in case. So, one resistor is around 500mA, 2 resistors in // is 1A. The module need to select the final stop voltage (by default 2.5v on Lithium) and then display the voltage, current and capacity until the end.

The charging part, using the IP2312, can change the charging current by changing one resistor. Also, a bridge can be done to charge to 4.35v nut by default it is 4.2v.

I use one mini USB plug to connect to a charger. In discharge mode, the 2 poles switch power the discharge module. In charging mode, it powers the charging module. 

Add multiple connectors and including a 18650 support.

I made a mistake at first to use a single pole switch with common ground. Big mistake. The discharge module measure the current through a shunt in the negative link of the battery. By connecting battery-charger module-discharger module by one ground, it was bypassing the shunt.  Spent some time to understand thus until I found the schematic of the HW-586...

Simple and convenient tools. Hope it can help,

Laurent