getExecutionCounts test code

Script-getExecutionCounts.js

// Basic getExecutionCounts test.                                                                                                      

var g = newGlobal('new-compartment');
var dbg = Debugger(g);
var s;
dbg.onNewScript = function (script) { s = script; };
var f = g.Function("i",
                   "line0 = Error().lineNumber;\n" +
                   "var s = 0;\n" +                   // line0 + 1                                                                     
	           "for (var a = 0; a < i; a++)\n" +  // line0 + 2                                                                     
                   "    s += a;\n" +                  // line0 + 3                                                                     
                   "return s;\n");

var N = 99;
f(N);

var counts = s.getExecutionCounts();
print(uneval(counts));
assertEq(Array.isArray(counts), true);

// Compile the total number of times each line is hit.  Some instructions are                                                          
// underreported or aren't reported at all; this technique of using the maximum                                                        
// number of hits per line copes fairly nicely with the noise.                                                                         
var hitsByLine = [];
for (var i = 0; i < counts.length; i++) {
    if (i in counts) {
        var lineno = s.getOffsetLine(i);
        var data = counts[i];
        var sum = data[0] + data[1] + data[2];
        if (lineno in hitsByLine)
            hitsByLine[lineno] = Math.max(hitsByLine[lineno], sum);
        else
            hitsByLine[lineno] = sum;
    }
}

assertEq(hitsByLine[g.line0 + 1], 1);
assertEq(hitsByLine[g.line0 + 3], N);