Allow maps to be passed to the empty expectation

[graywolf336]

Description

This allows Map to be used in the toBeEmpty expectation.

Closes #462

Checklist

• I am an awesome developer and proud of my code
• I added / updated / removed relevant unit or integration tests to prove my change works
• I ran all tests using npm test to make sure everything else still works
• I ran npm run review to ensure the code adheres to the repository standards

Additional Information

I would love to get some feedback on the code inside the empty-matcher file, I do not like the nested if statements but I couldn't come up with a better way at the time.

As crazy as this sounds, Map keys can be anything, including another object. How should the stringify function handle them? I put a placeholder there to show the size/length of it, but I know that can be improved so it is less confusing.

Also, some reason the npm test command is failing on my Windows machine (I'm away from my usual development environment which is Linux) at the step npm link && install-self.

[jamesadarich]

This looks brilliant thanks very much, I'll test this in a bit when I get to my computer but looks good from what I can see. Thanks for the contribution, look forward to your suggestions etc in future :)

[jamesadarich]

I'll have a look into your Windows issue as well. Does which node and windows version were you using?

Having a ponder about a refactor for EmptyMatcher as well :)

[jamesadarich]

I've had a thought about a refactor here. Perhaps it makes sense to move the logic to more specific classes that all implement a similar interface instead of abstracted to a common function.

E.g. ArrayMatcher, MapMatcher implement the toBeEmpty function from interface IEmptyMatcher.

Should simplify the individual functions. What are your thoughts @graywolf336?

[graywolf336]

Sounds like a fantastic idea 👍 would be allow the empty match to be extended with ease, which I like that.

[pathurs]

Hey @jamesadarich,

Did you want to accept this PR and create a separate issue for separate matchers?

[jamesadarich]

Yep @pathurs this sounds like a great plan 👍 I'll create one now, once CI has finished we can get it merged

[jamesadarich]

thanks @graywolf336 we'll get this published soon 👍