title: How to unit test a void method
body: <p>I am trying to reach more code coverage. I have an "informational" method that just triggers notification, and response is not required. How do I unit test it?</p>
  
  <pre><code>public error(message?: any, ...optionalParams: any[]) {
      if (this.isErrorEnabled()) {
        console.error(`${this.name}: ${message}`, ...optionalParams);
      }
    }
  </code></pre>