About sign of convergence Ermakov's
Ermakov's test of a strictly positive series with monotonically decreasing terms is considered. Since in the mathematical literature describes, as a rule, only the most important special case of the so-called Ermakov's test (continuous form), the proof of Ermakov's test is given in general, including the form of limit. The discrete analog of Ermakov's test found by the French mathematician Fabri is considered. Its incompleteness is pointed out and its proof partially different from that of Fabry is prompted.