  Intrinsic, in-plane anisotropy of electrical resistivity was studied on
mechanically detwinned single crystals of SrFe$_2$As$_2$ above and below the
temperature of the coupled structural/magnetic transition, $T_{\textrm{TO}}$.
Resistivity is smaller for electrical current flow along the orthorhombic $a_o$
direction (direction of antiferromagnetically alternating magnetic moments) and
is larger for transport along the $b_o$ direction (direction of ferromagnetic
chains), which is similar to CaFe$_2$As$_2$ and BaFe$_2$As$_2$ compounds. A
strongly first order structural transition in SrFe$_2$As$_2$ was confirmed by
high-energy x-ray measurements, with the transition temperature, and character
unaffected by moderate strain. For small strain levels, which are just
sufficient to detwin the sample, we find a negligible effect on the resistivity
above $T_{\textrm{TO}}$. With the increase of strain, the resistivity
anisotropy starts to develop above $T_{\textrm{TO}}$, clearly showing the
relation of anisotropy to an anomalously strong response to strain. Our study
suggests that electronic nematicity cannot be observed in the FeAs based
compounds in which the structural transition is strongly first order.
