AssertionError

[boneskull]

In mochajs/mocha#1635, we are considering adding support for suite continuation if a hook throws an AssertionError.

Because expect.js doesn't actually throw an AssertionError upon failure, this feature will simply not work with expect.js.

Would like to start a discussion about expect.js throwing AssertionErrors, much like Chai or should. I imagine:

• in a server context, use require('assert').AssertionError

• in a client context, the assertion library must define a global AssertionError. Example:

  var AssertionError = function(message, actual, expected) {
    this.message = message;
    this.actual = actual;
    this.expected = expected;
    this.showDiff = true;
  };
  // or whatever you need to do for old browser support
  AssertionError.prototype = Object.create(Error.prototype);
  AssertionError.prototype.name = 'AssertionError';
  AssertionError.prototype.constructor = AssertionError;

Would this break backwards compatibility? Any user checks of err instanceof Error should still work.