Consider a function $f(z)=z^{2}+z+1$ where $z \in \mathbb{C}$ is a complex variable. A simple closed contour $\gamma$ in $z$-plane encloses the point $z=1+0 j$.
The value of integral $\oint_{\gamma} \dfrac{f(z)}{z-1} d z=$ $\_\_\_\_\_\_$.
- $6 \pi j$
- $3 \pi j$
- $12 \pi j$
- $\pi j$
