Assertions library for node.js? [closed]

Question

Assertions provided by node.js assert for unit-testing are very limited. Even before I've written the first test I was already creating a few of assertions as it was clear I will keep re-using them.

Could you recommend some good library of assertions to test for common javascript situations (object structures, objects classes, etc., etc.)?

Ideally it should integrate well with nodeunit (or, better, extend it's assertions) - my assertions do not, I have to pass them test as an extra variable...

The only one I've seen is Chai. What could you say about it?

Answer 1

It's also somewhat a matter of preference — whether you prefer to test with the assert syntax or BDD-style assertions (smth.must.equal(...)).

For the assert style, Chai's assert may work well. It has more built-in matchers that Node's own assert module.

If you find the BDD-style more readable and fluent, all three do that:

• Chai.js.
• Must.js by yours truly.
• Should.js.

They differ primarily by the simplicity or complexity of their API when it comes to various matchers. Their essential equality assertions, though, are interchangable — foo.must.equal(42) or foo.should.equal(42).

There's one thing you need to be aware when picking Chai.js and Should.js that I argue is a fundamental design mistake — their practice of asserting on property access as opposed to calling the matcher as a function. I've written a critique of asserting on property access and how it may cause false positives in tests.