code: function Expectation (spec, options) {
    this.id = ++id;
    // Static fields:
    this.specification = spec;
    spec.expectations.push(this);
    this.stopOnFailure = spec.stopOnFailure;
    this.verbose = spec.verbose;
    // Optional fields:
    this.thunk = undefined;
    this.code = undefined;
    this.weight = 1;
    Object.assign(this, options || {});
    spec.description.log_("Expectation: " + this.actual);
    this.index = ++this.specification.index;
    this.specification.expectationAttempted += this.weight;
    // Internal (dynamic) fields:
    this.raisedException = false;
    this.exception = null;
    this.pass = false;
    this.runEndHook = false;
  }
docs: *********** Expectation *************