Jasmine: Testing complex types for equality
Jasmine comes with two matchers that test for equality. The first is toBe:
Copyexpect(first).toBe(second)
toBe passes when first === second. Unfortunately this is useless for non-primitive values because Javascript is a horrible language.
However, Jasmine comes with another matcher toEqual:
Copyexpect(first).toEqual(second)
This matcher behaves as a human would expect for types like the following:
- Arrays
- Objects
- Nested array/object constructs
- Regular expressions
-
Dateobjects NaN- Exceptions
Custom equality matchers
You can also teach toEqual additional notions of equality. E.g. the following code will teach toEqual to test two jQuery collections for equality:
CopybeforeEach -> jasmine.addCustomEqualityTester (first, second) -> if first instanceof jQuery && second instanceof jQuery first.is(second)
Using Jasmine's equality logic in your own matchers
You can use Jasmine's built-in equality logic (plus the logic added by custom equality matchers) like this:
CopybeforeEach -> jasmine.addMatchers toEqual123Array: (util, customEqualityTesters) -> compare: (actual) pass: util.equals(actual, [1, 2, 3], customEqualityTesters)
Note how the compare method is passed two arguments util and customEqualityTesters, which are both needed to access Jasmine's equality logic.
By refactoring problematic code and creating automated tests, makandra can vastly improve the maintainability of your Rails application.
