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<v ->Hi, guys and welcome back.</v>

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Next up we're going to be testing classes.

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So, we're gonna first of all

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create a new Python file

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that's gonna be our printer.

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And here we're going to create a printer class

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that has a simple, in it, method

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with the pages per second

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and the capacity of the print.

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And we're gonna have a simple class here

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that just allows to mock a print.

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So we've created this simple printer class

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and what it does is it takes two values,

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how many pages this printer prints in one second

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and how many pages it has capacity for.

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How much ink it's got left, if you will.

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Then there is a print method

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that prints a certain number of pages

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unless the pages are above the current capacity

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in which case, it raises a printer error.

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After that, the capacity decreases

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by the number of pages printed

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and it returns a nice message there

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that tells you how many pages were printed.

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We've autograted a custom printer error class

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that is what is raised here.

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Now, let's go ahead

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and create a new file called test_printer.py.

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And here is where we're gonna be writing our tests

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for this printer.

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Now, there is a couple of things that we need to look at

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when testing a class.

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The first thing is that we need to create a class object

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so we need to think about

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whether we wanna create that on every test

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or we wanna create it once

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for the entire test case.

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We're going to look at how to do that

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and also on writing tests for this printer

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in the next video, so I'll see you there.