Add toBeHexadecimal Method

[mvpowers]

Feature Request

Description: Add a method to check whether a string is a valid hexadecimal.

Possible solution:
expect('#e3e3e3').toBeHexadecimal();
expect('#fff').toBeHexadecimal();

This could be helpful for some front-end tests. I'll be happy to submit a PR if this sounds like a good idea.

[mattphillips]

Hey @mvpowers I like the sound of this matcher, feel free to send a PR 😄

[denizdogan]

@mvpowers @mattphillips Not that I oppose the idea, but shouldn't this be implemented as a simple toMatch? The following seems simple enough (not tested):

const hexadecimal = /^#[a-f0-9]/i
expect('#e3e3e3').toMatch(hexadecimal)
expect('#fff').toMatch(hexadecimal)

[mattphillips]

@denizdogan I think this matcher is a useful one to save people having to write out the regex and reads nicer than toMatch

[denizdogan]

It's too late for this comment I guess, but hexadecimal notation can look different in different languages. CSS is the only one I know of that uses # as the prefix, JS itself uses 0x, HTML uses &#x, etc. It's not obvious in the name toBeHexadecimal that it's the CSS variant that's being tested against. EDIT: It's also not obvious that the value is expected to be 3 or 6 characters in length.

[mattphillips]

@denizdogan I'm happy to extend out it's behaviour to support other languages if you want to send a PR?

[denizdogan]

@mattphillips I'm not really interested in sending a P.R. for this particular method (I would have just used the regex version I suggested earlier) but I'm just pointing out that "being hexadecimal" is a broad term and if the method is supposed to check that the value is a valid hexadecimal CSS value of length 3 or 6, it would be good if that was reflected somewhere in the documentation too.