title: How to make a Chai custom assertion fail?
body: <p>This minimal example custom chai assertion should fail. It does not. What is missing to make it fail?</p>
  
  <pre><code>const chai = require('chai');
  
  chai.Assertion.addMethod('test1', function() {
      this.assert(
          false,
          "Failed",
          "Failed",
          "foo",
          "bar"
      );
  });
  
  chai.expect({}).to.be.test1;
  </code></pre>