Sorry I should have been more clear.

We should remove the `assert.equal(map.mappings, util.emptyMap.mappings); ` asertion because it is equivalent to using `==`. The reason the assertion is passing is because it is coercing the empty arrays to a string that happens to be equal. At the end of the day, it isn't a useful assertion, and the `length` assertion above it is more than satisfactory.