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Instructor: In the last section

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we put together a test around our comments reducer.

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At the very end of the video, I made a small change

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to the test to make sure that the test failed

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and it looked like it did in fact fail the way I expected.

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So I'm now gonna go back over

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to my test file and restore it to its working state.

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Cool.

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Now if I go back to my list of tests, I wanna write

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remember we also wanted to make sure

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that if we call the reducer

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with an action that has an unknown type

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we should not see an error

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or nothing should really just go wrong.

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So this test will be pretty straightforward.

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I'm gonna add in another it statement

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inside my test file and I'll give it a description

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of something like, handles action with unknown

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type.

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So in this case,

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we can write an even more terse test than we did previously.

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All we really have to do is call our comments reducer.

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We can pass in an initial state if we want to

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but we definitely don't have to.

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And then we can pass in an action that does not

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even have to have a payload or a tight property.

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So passing in an empty object essentially counts as passing

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in an action with an unknown type because it has no type.

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If you wanna be a little bit more explicit,

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you could always pass in

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an actual type property with some random string here.

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It's totally up to you.

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Really, both of them are more

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or less the same way of testing this reducer.

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You can really take it either way.

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So then all we have to do here is probably

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take whatever gets returned from comments reducer.

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I'll again call it new state.

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And then I'll write an expectation to say

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that new state should simply be an empty array.

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So we're just gonna kinda make the case to say,

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Hey, you know what?

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Comments reducer did not throw an error

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and as usual as expected,

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it's just gonna return whatever state it was provided

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which should be an empty array.

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So I'll say expect new state to equal empty array,

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like so.

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And that's pretty much it.

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Honestly, these kind of unknown action type tests right here

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you can definitely do them.

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I personally don't find them the most useful thing

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in the world.

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I think it's a lot more useful to write tests

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around actual action types that you know are going to come

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across the reducer.

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All right, so we'll flip back over

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to our test suite really quick

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and just make sure this is passing as well.

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And it looks like we're good to go.

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Now this is one case where I won't make you try to

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make the test fail here

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cuz it's kind of hard to make this test fail.

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So if you wanna give it a try, go for it.

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Otherwise, let's continue in the next section

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and we'll start writing some tests around the next part

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of our application, which will be our

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SaveComment action creator.