The ornamental design for a diagnostic testspecimencollector, as shown and described.
FIG. 1 is a front perspective view of a diagnostic test specimen collector showing my new design;
FIG. 2 is a rear perspective view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a left-side elevational view thereof;
FIG. 6 is a right-side elevational view thereof;
FIG. 7 is a top plan view thereof; and,
FIG. 8 is a bottom plan view thereof.
The broken lines immediately adjacent the shaded areas represent the bounds of the claimed design, while all other broken lines are directed to unclaimed portions; the broken lines form no part of the claimed design.