Effective PyCharm Transcripts
Chapter: Unit testing
Lecture: Measuring test quality with code coverage
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0:00
These air conditioned tests were great but let's just comment them out just for a moment so we can see a little bit more in action.
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If we've got a simple little program like this one file, 100 lines of code. We want to know how much of our tests actually interacts
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with how much of that program. We can probably reason about it, even though it's not 100% obvious, we can probably figure out that yeah,
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this these tests are exercising the code well enough. If you've got code that is not being run at all by the tests then the
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tests say absolutely nothing about the quality of that code other than maybe it can be parsed by Python. So maybe the syntax is mostly okay,
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so how do we know, you're in a real project We might have hundreds of tests and thousands of lines of Python.
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How do we know what part of code being tested by the test we've written so far, that's code coverage. So we can go up here and we can press
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another one of these buttons we've seen profiling debugging regular running, but now we have run with coverage the first time you run this,
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it might say coverage is not installed. Just click enable bundled coverage and you should be good to go,
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we click this and it takes a little bit longer because it's thinking a whole lot about what's happening and then whoa,
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there's a lot of information on the screen here and check this out. So we've got a like a graphical thing going on over here,
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like an Excel type report, Scroll down into the demos projects, a bunch of this is not covered because it's not really part of this project.
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Let's go to the one that is the tests. Well, guess what? The test ray? And when we ran the test, that doesn't mean anything. Let's check this out.
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So over here, in core we have 75% of the lines and program, we're not exercising that. So that's useful information already.
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If we put that to the side, look at this, this is way better over here. It gives you right within the project,
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a nice report showing you for each level that you go into it. Right? So here's our core definitely tested and now even better remember how we had
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GIT hub showing us on the side here, look at this. So for example, here this green code. This means it was hit by code coverage and this red
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part here means that it wasn't. So that is fantastic. I'm not sure if this comes through what color comes through in the video when it's exported,
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but light green, faint green and faint red here. If we want to improve the code coverage of this actual file here of our core
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Well, we need to make a couple of things happen. We need to make this case run,
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we've run the test but we've never run this and we've run this test but we've never run this. Let's go in,
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quote, right. Another testament to re enable this one. This will be about a non existent table.
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So when I run it, notice this red part should go away right again. Running again with coverage and here we go.
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Look that first part about the non existent table. Now, that's running fantastic. Let's go and finish it off by running that little
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bit there. That's going to be this last test. You can run with coverage. Perfect it, pass and check it out. All of that is good.
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There is something else going on here that still thinks it's not running. But when I look at this file,
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it looks like this is 100% code coverage, as far as I'm concerned.