in x-test.js [802:808]
static kickoffTestPlan(context, stepId) {
const count = XTestRoot.count(context, stepId);
const level = XTestRoot.level(context, stepId);
const tap = XTestTap.plan(count, level);
XTestRoot.output(context, stepId, tap);
context.state.steps[stepId].status = 'done';
}