Chai: how to test for undefined with ‘should’ syntax

This is one of the disadvantages of the should syntax. It works by adding the should property to all objects, but if a return value or variable value is undefined, there isn’t a object to hold the property.

The documentation gives some workarounds, for example:

var should = require('chai').should();
db.get(1234, function (err, doc) {
  should.not.exist(err);
  should.exist(doc);
  doc.should.be.an('object');
});