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If you write your tests first, then you'll be forced to write code that is easy to test.

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So the first step of test driven development is to identify a meaningful test cases from the requirements

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when the story adds a movie to its collection.

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We need to check if the story contains the movie that was just added.

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Testified.

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The store contains the movie after its added.

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If that test succeeds, then we know that our code works.

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The second thing we need to check for is if a movie gets removed after we sell it.

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Test if the movie gets removed.

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After being sold.

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And now in the event that someone tries to buy a movie that was already rented, we need to make sure

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the application throws an illegal state exception test for an illegal STD exception for selling a rented

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movie.

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The other two test cases should be fairly intuitive if someone rents a movie, we need to check if that

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movie becomes rented, test if the movie becomes rented.

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Otherwise, if someone returns a movie, we need to write a test that ensures the movie is available

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again.

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Test if the movie is available again.

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If all of the tests we write pass, we can rest assured that our code doesn't have any bugs.

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Now, you might be wondering why did I code the constructor getters and setters without unit testing

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them first?

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That's because they're always doing the same thing and testing them is meaningless.

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They don't offer meaningful logic.

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OK, that's all for part one, we've identified every meaningful test case and now we can start unit

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testing.