1. A computer program product for classification based concurrent test instrumentation of an instrumented program to be tested, the computer program product comprising: a computer readable storage medium having computer usable program code embodied therewith, the computer usable program code comprising a computer usable program code to: determine classifications of a plurality of test instruments in an instrumented program, wherein the plurality of test instruments at least includes a first test instrument and a second test instrument in a first classification of the classifications and the plurality of test instruments includes at least a third test instrument and a fourth test instrument in a second classification of the classifications; instantiate the first test instrument in the instrumented program; increment a counter for the first classification after the instantiation of the first test instrument and decrement the counter for the first classification when the first test instrument is no longer active; prevent concurrent instantiation, in the instrumented program, of the second test instrument with the first test instrument based, at least in part, on the first and second test instruments being in the first classification, wherein the program code to prevent concurrent instantiation, in the instrumented program, of the second test instrument with the first test instrument comprises program code to, determine that the instrumented program is attempting to instantiate the second test instrument; determine that the first test instrument is currently instantiated for the instrumented program, wherein program code to determine that the first test instrument is currently instantiated for the program comprises program code to determine that the counter for the first classification is greater than zero; prevent access to code of the second test instrument in response to a determination that the first test instrument is currently instantiated; concurrently instantiate, in the instrumented program, the third and fourth test instruments based, at least in part, on the third and fourth test instruments being in the second classification; create a copy of the instrumented program with an indication that prevents instantiation of the first test instrument in the copy and that allows instantiation of the second test instrument; and instantiate the second test instrument in the copy.