code: function(spec) {
        this.currentSpec = spec
        try { this.evalBody(spec.body) }
        catch (e) { fail(e) }
        spec.runDeferredAssertions()
        destub()
        this.stats.specsFinished++
        this.stats.assertions += spec.assertions.length
      }
docs: Run a spec.
  
  @param  {Spec} spec
  @api public