Now that we have a basic knowledge of Chai, we can continue with our coding. The code we already have in place is clearly not correct, so we need to add another test that forces us to make the code right.

Currently, we are implementing the rule about errors for nonpositive numbers, so we should finish it before continuing. Which test could we add to make our implementation fail? We can try testing the validator with valid numbers. Let's see the result:

describe('A Validator', function() {
  it('will return no errors for valid numbers', function() {
  }); it('will return error.nonpositive for not strictly positive numbers', function() { expect(validator(0))['error.nonpositive']); ...

Get Learning Behavior-driven Development with JavaScript now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.