  In this paper we consider a random variable $Y$ contamined by an independent
additive noise $Z$. We assume that $Z$ has known distribution. Our purpose is
to test the distribution of the unobserved random variable $Y$. We propose a
data driven statistic based on a development of the density of $Y+Z$, which is
valid in the discrete case and in the continuous case. The test is illustrated
in both cases.
