Prevent falsy nodes from being counted as children

[nishitaniyuki]

Like #151

I have a problem like below.

test('component should have no children', t => {
    const component = shallow(
        <div>
            {undefined}
            {undefined}
        </div>
    );
    t.same(component.children().length, 0) // This should be success, but fail since length is 1.
});

I expect null, undefined and false should not be counted as a child node.
What do you think??

[lelandrichardson]

a simpler solution here might be to just check and see if child is false, null, or undefined before pushing it into the result? The recursive nature of children will be taken care of in React.Children.forEach in this case.

[nishitaniyuki]

Exactly.
Can I rewrite & send new PR?(I'm new to github...)

[lelandrichardson]

@nishitaniyuki yep! Update your code and then push the changes to github. this PR should update automatically.

When you update your code, it's best for a change like this if you can make all of your changes into a single atomic commit. Let me know if you need any extra help with this.

[lelandrichardson]

FYI, you can change the code and then use git commit --amend to combine the changes into the latest commit so that it stays as a single commit.

[nishitaniyuki]

I've combined the changes, thank you!
Please check it.

[lelandrichardson]

Thanks for working on this. I believe we omit these nodes from being passed into methods such as .findWher(), so omitting them here feels more consistent.

[ljharb]

We omit null nodes, but not usually all falsy nodes - what about the empty string and NaN?

[lelandrichardson]

@ljharb i'm not too worried about NaN, but we should have defined behavior for all things that React considers non-renderable: false, null, and undefined.

We explicitly don't traverse false and null. It looks like we might (incorrectly) handle undefined though:

https://github.com/airbnb/enzyme/blob/master/src/ShallowTraversal.js#L32

[nishitaniyuki]

i'm not too worried about NaN, but we should have defined behavior for all things that React considers non-renderable: false, null, and undefined.

I agree.

We explicitly don't traverse false and null. It looks like we might (incorrectly) handle undefined though: https://github.com/airbnb/enzyme/blob/master/src/ShallowTraversal.js#L32

I expect this also should skip undefined.

[lelandrichardson]

@nishitaniyuki great, thanks!