Goodness of fit tests indicate whether or not it is reasonable to assume that a random sample comes from a specific distribution.
"They are a form of hypothesis testing where the null and alternative hypotheses are:
H0: Sample data come from the stated distribution
HA: Sample data do not come from the stated distribution
These tests are sometimes called omnibus tests.
Ricci, V. (2005). Fitting distributions with R.
Retrieved from: http://cran.r-project.org/doc/contrib/Ricci-distributions-en.pdf