“…For instance, Dette and Marchlewski (2010) considered a robust test for homoscedasticity in nonparametric regression. Under a partly linear regression model, Bianco et al (2006) proposed a test to study if the nonparametric component equals a fixed given function, while Boente et al (2013) considered the hypothesis that the nonparametric function is a linear function under a generalized partially linear model. On the other hand, Sun (2006), Dette et al (2011Dette et al ( , 2013 and Kuruwita et al (2014) considered the problem of comparing quantile functions.…”