Output capacitance of H-Bridge IC (DRV8432DKD) for snubber design
You can measure it in circuit by measuring the ringing frequency across the motor with and without a known value added capacitor. 

Since \$f_{ring} = \frac{1}{2\pi \sqrt {L C}} \$, if you measure the ringing with and with out \$C_{add}\$  as fring1 and fring0 respectively, then 

C = \$\frac {C_{add}}{x^2 -1}\$ where x = \$ \frac {f_{ring0}}{f_{ring1}}\$ 

This method is described in this NXP application note AN11160 Designing RC Snubbers.