src/third_party/mozjs-45/js/src/jit-test/tests/debug/breakpoint-10.js

var g = newGlobal();
var dbg = new Debugger(g);

var fscript = null;
dbg.onNewScript = function(script) {
    dbg.onNewScript = undefined;
    fscript = script.getChildScripts()[0];
}

g.eval("function f(x) { arguments[0] = 3; return x }");
assertEq(fscript !== null, true);

fscript.setBreakpoint(0, {hit:function(frame) {
    assertEq(frame.eval('x').return, 1);
    assertEq(frame.arguments[0], 1);
    return {return:42};
}});

assertEq(g.f(1), 42);