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Now that we've identified every test case, the second step is to start unit testing.

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Your first task was to set up a method annotated with before public void setup.

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And we're going to give this method of before annotation, remember that when you edited a method with

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before, then it's going to run before each test and each test is going to depend on us setting the

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cart equal to a new object of the cart class.

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Now we can start unit testing, we'll follow the order from requirements dot text, the first test case

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tells us to check if the store contains an item after it's been added.

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So I'll create a unit test named item added test.

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And here I need to research the story contains an item that was added and checking if a store contains

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an item, depends on us adding the item first.

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So we'll do that inside the before method carport add.

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Will add a new item.

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Pepsi won ninety nine.

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And we'll add another item to the shopping cart cart that add new item, Krush, also 199.

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All right, but the store doesn't have an ad method.

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So we need to go to Kadirgamar public void add.

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And the before method implies that ad should receive an object of the item class.

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And here, I guess I'll just have to add a new copy of the item object inside the array list.

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OK.

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And now how do we make sure the aid method is working as it should inside the item added unit test?

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We need to check if the cart contains the item object that was added.

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So we're going to use a true.

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To check if the cart contains the crushed object.

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This test asserts the cart contains a certain item, and now inside Staudt Java, we need to write code

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to make the test fail, something to create a public boolean method called contains.

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And here, the unit test implies that our method needs to receive an item object.

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Again, it's kind of nice that we're writing our code based on how we set up our tests.

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And here the only thing we can do is return a boolean that checks if this items.

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That contains the item parameter.

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All right, our test should fail.

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Which is fine, because that's the first step to writing a unit test and it says that it was expecting

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true, but our unit test returns false.

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So this is where you ask yourself, OK, why is the test failing?

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If you put a breakpoint here.

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You can see that the cart already contains two objects courtesy of our before method.

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The objects are equal in terms of state, their fields are equal, but remember that contains uses the

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default equals method to compare item objects.

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So it compares the reference of each item against the item parameter.

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The reference that we're passing in isn't equal to any of the references inside the array list.

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So ultimately, Java determines that the aerialist doesn't contain the object being passed in.

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But if we create our own equals method from just the item class then contains is going to use that one

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instead.

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So inside the item class, we're going to customize the equals method.

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The equals method needs to return a boolean.

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And receives an object, what's the type of that object we don't know.

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It can be any object.

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First, we're going to check if the object that we're comparing against is No.

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Because if it happens to be null, then there's no way it equals the item object that's calling this

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method, let's assume the object is it now then we need to check if it isn't of type item if the object

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isn't an instance of the item class.

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Then return false.

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OK, so at this point, the object, is it no, it is an instance of item, so we can typecast it to

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type item.

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And finally, we got to check if the objects fields are equal to the current object that's calling this

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method.

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We're going to compare the name and price from the object that's calling this method to the one that's

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being passed in as a parameter.

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All right, let's run the test now.

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And it passes.

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Here you can visualize it, the contains method is using your equals method to compare your object against

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each item in the aerialists.

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This points to the current item that's called the equals.

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And here is the parameter.

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The parameter is not known.

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It is an instance of item.

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But the fields aren't equal, so equals returns, falls for the first element.

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And if you keep going, the second time equals gets called.

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This parameter is not known.

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It is an instance of item.

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And the fields are equal, so equals returns, true.

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And because equal is return, true contains determines that the Israelis does contain that object and

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it returns true as well and our unit test passes.

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All right, since the unit test passes, we can rest assured that our code doesn't have any bugs.

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But can I be refactored?

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The answer is no.

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The code is as elegant as it's going to be.

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The second test case tells us the card should skip a duplicate item, so I'll create a unit test named

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SIP's Duplicate.

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And here I'll make an assertion using a certain false assert, false expects the value to be false.

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And we're expecting the odd method to return false if we add a duplicate item.

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So back in Córdova.

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We have to write code to make the test fail, so I'm going to return true.

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Our test should fail, which is fine.

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It says that it was expecting faults, but our unit test returns true, so back in Car Java, we got

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to write code to make the test pass.

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We'll say if items that contains the item being passed in.

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Return false.

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Otherwise, we'll return true and add that item to the aerialists.

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OK, rerun the test and it passes so we can rest assured that our code doesn't have any bugs, but can

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it be a refactored?

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The answer is no.

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The code is as elegant as it's going to be.