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`coverage.py`'s reports are great but sometimes you want something more visual or a page you can share with other people. Let's see how to generate HTML reports from `coverage.py`.
Notes
coverage html will generate the HTML report. By default, it'll live in the htmlcov/ directory.
To serve HTML files (and CSS, JS, etc) directly from Python, we used the http.server module through python -m http.server.
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So coverage.py is pretty awesome, huh?
0:00
Well let's look at one last feature of
this little library to see
0:02
a way that it's even more amazing.
0:05
Coverage's reports are pretty great.
0:07
But sometimes I like a visual reference to
where I'm covered and where I'm not.
0:10
So actually, instead of generating a
report just in the terminal, you know,
0:14
just this coverage report that we've been
doing, we can actually do coverage html.
0:18
And if I refresh over here, just so you
can see what's here.
0:27
We now have this html cov, folder.
0:35
So, because of one of the limitations of
workspaces with how it pays
0:39
attention to Python and non-Python, stuff
like that,
0:43
we have to do something a little bit
different here.
0:46
So, what we're actually gonna do, we're
gonna do Python -m http.server and
0:48
this serves up a very basic HTTP server.
0:53
And then we're gonna go to our preview.
0:57
And we have 8,000 here so we want 8,000
here.
1:00
And then we're gonna go into htmlcov.
1:01
Look at this, this is a nice, pretty view.
1:04
We can see that my dice thing has 50
statements.
1:09
Not any of them are missing.
1:12
We're at 82%.
1:13
Overall we're at 89%.
1:14
But here's what's really cool, here's
what's awesome.
1:16
I can click here where it says dice.
1:18
And now I'm looking at my dice file, and I
can see the lines that are not covered,
1:22
because they're red and highlighted, which
I'm sure you guessed that.
1:26
And the lines that are covered because
they're red.
1:29
Now if I had told coverage.py to skip
certain lines.
1:32
Then they'd be, they would appear in
yellow.
1:36
I'll leave that for you to find inside the
docs
1:38
which of course I will link to in the
teacher's notes.
1:41
So you can see that we have a few
different things that aren't tested.
1:43
So for one thing is we don't have this
dunder add method being tested or
1:48
this r add for reverse add, or contains or
get,
1:51
we have a lot of things that aren't really
tested.
1:55
So, let's write a test that does this.
1:57
So go back over here, to our test.py.
2:01
And down here at the bottom of our roll
tests,
2:03
lets add a new test and we'll say def
test_adding.
2:11
And we're gonna say self.assertEqual,
2:18
self.hand1 plus self.hand3.
2:23
And that should be equal to the sum of
2:28
self.hand1.results plus the sum of
self.hand3.results.
2:32
All right, kind of a long test but yeah,
it works.
2:41
So then we're gonna come down here and
we're gotta kill this.
2:48
And then we have to run our tests again.
2:51
So coverage run tests.py.
2:53
And then we have to generate the HTML
again, coverage html.
2:59
And then we have to serve our stuff again,
'kay?
3:03
But then we can come and we can refresh
this and
3:07
we see that add and radd are now tested.
3:12
Now, we only meant to test add, why did
radd get tested?
3:15
Well it has a lot to do with these
internals here.
3:18
When we call this int(self) plus other, it
comes up here to end.
3:21
Calls this, that's fine, that's how we get
the int self but
3:25
when it gets to this plus other, it
doesn't know what it's doing.
3:28
It doesn't know how to add a number to a
roll.
3:30
So it calls a reverse add which says, hey,
3:34
see if you can figure out how to add
yourself to me.
3:36
When it gets to reverse add, it goes oh, I
turned myself in to an end.
3:38
So, we go, we run through that.
3:43
We're not going to go in to all these
internals of how Python's magic
3:45
methods work.
3:48
That's for a later course.
3:48
But you can kind of see the movement of
stuff.
3:50
But having these HTML reports is amazingly
handy for
3:54
figuring out what you need to cover.
3:57
Those HTML reports are mind blowing the
first time you show them to someone.
4:00
I've seen so many jaws drop.
4:03
I'll just assume that yours did too, okay?
4:05
Well with that, we're done with another
course.
4:07
If you haven't written tests before either
in Python or
4:09
in another language, I hope you'll start
to.
4:12
It was a part of development that I
shunned for a long time.
4:14
And I was way worse off for it.
4:17
Testing makes your code safer, smarter,
and much more reliable.
4:18
Happy testing.
4:22
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