should.approximately support

[axelpale]

I propose ShouldJS's approximately(value, delta, [description]) assertion should be a part of the core API of Chai. One could use .within(above, below) to do the job but writing the both limits easily causes code similar to:

var epsilon = 0.01;
...
var val = 10;
(9.99).should.be.within(val - epsilon, val + epsilon);

versus drier:

var epsilon = 0.01;
...
`(9.99).should.be.approximately(10, epsilon);`

Furthermore because Chai claims to have Should interface, having all ShouldJS's methods is expected. Therefore to have a separate Chai plugin does not feel practical.

[axelpale]

To underline the inconvenience, in my case (PhantomJS + Mocha + Chai + chai-jquery) going back to original ShouldJS instead of Chai is not an option because the benefits from chai-jquery.

[keithamus]

Hey @axelpale thanks for the issue!

We have .closeTo which I think it what you're after, to quote the docs:

.closeTo(expected, delta)

• @param{ Number }expected
• @param{ Number }delta
• @param{ String }message_optional_
  Asserts that the target is equal expected, to within a +/- delta range.

expect(1.5).to.be.closeTo(1, 0.5);

If you'd like, I'll happily accept a PR which aliases approximately to closeTo. Heres the code for .closeTo, and above that is an example of how we create multiple aliases for a method. Simply refactor the closeTo code to use the alias syntax, and add some new tests for the alias, and I'll merge 😄

[berkerpeksag]

The alias is added in 7fe23e9. This can be closed now.

[keithamus]

👍

[axelpale]

Oh, nice! Thank you guys.