Kirchhoff's laws with current source in a circuit
\$i\$ is the current in the loop in clockwise direction. Then,
$$-V_{I_1} + iR_1 + V_1 = 0\tag{KVL}$$
$$i = I_1\tag{KCL}$$

where, \$V_{I_1}\$ is the voltage across current source. Then from KCL and KVL,

$$V_{I_1} = V_1+I_1R_1$$