add contains assert

[brunoqueiros]

A new assert to check if a string contains certain string.

t.contains(value, expected, [message]);

[sindresorhus]

Hmm, not sure about this. Now that we have power-assert support it doesn't really make sense to add a bunch more assertion methods as you can just use t.true(). In this case it would be t.true(foo.includes('bar'));, although [].includes is currently not working, but will be fixed.

[brunoqueiros]

I think that is easier to have more assertions because the test file will be cleaner and more easy to maintaining. I think there should have both, that way the user can choose what use.

[sindresorhus]

t.contains(foo, 'bar');
// vs
t.ok(foo.includes('bar'));

// @twada @uiureo

[shinnn]

Contrary to the PR author's opinion, t.contains won't simplify the test file, I think.

There are a lot of JavaScript objects that have indexOf method (array, string, Node's buffer, ...), but this t.contains function doesn't check its argument type. So whenever we use t.contains we should also check the object type.

[brunoqueiros]

It's not even necessary, your arguments are right. I'll close the PR.

[twada]

I agree with @sindresorhus and @shinnn.

I've developed power-assert to prevent tests from bloating assertion methods. Less is more.

I know it's a bit opinionated. But AVA is opinionated too ;)