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The `unittest` library has many different assertions but some are more commonly used than others. Let's look at how to check for membership, what class a variable is an instance of, and a couple of others.
New Terms
assertIn(x, y) - Make sure x is a member of y (this is like the in keyword)
assertIsInstance(x, y) - Make sure x is an instance of the y class
assertGreaterEqual(x, y) - Make sure x is greater than or equal to y
assertLessEqual(x, y) - Make sure x is less than or equal to y
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If you've been writing Python for a while,
you've probably gotten pretty used to
0:00
using in key word the for checking
membership.
0:03
You want to know if a certain value is in
a list or dictionary.
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Lots of time we want to know if this is
true when we're writing tests too.
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So unit test gives us assert in and assert
not in.
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There are a couple of other handy lists,
[UNKNOWN] and dictionary assertions, too.
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Let's take a look at them.
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For our next set of tests, we're going to
use a couple of new classes that I wrote
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they're here in this dice dot pie file
inside the dice directory.
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And, so these represent a die roller, like
you might use for a table top game or
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a role playing game.
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You can make a roll, where is that class?
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There's the class.
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You can make a roll of dice with a string
like one d six or
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two d six or five d eight, whatever.
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And it'll create how many dice with
however many sides and
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it rolls them to get a number.
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So, I'm going to test a few things in this
module.
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The first thing I want to test is whether
or not a die up here is created correctly.
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So, let's set up a new file here that
we're gonna call test.py.
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And we need to to import unittest and we
need to import dice so
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we have everything set up, and lets do a
class DieTests.
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Unittest.TestCase, and we're gonna use the
setup method.
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So def setUp, and I'm gonna create just a
couple of dice directly.
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I'm gonna make a d6, which is dice.Die
with six sides.
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And I'm gonna make a d8, which is dice.Die
with eight sides.
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Okay.
So now, let's test the creation of a die.
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So they've been created and
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I should now be able to do
self.assertEqual(self.d6.sides, 6).
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The number six should have six sides.
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And I just do self.assertIn(self.d6.value,
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range(1, 7) because remember with range,
we have to specify a higher end
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that's one higher than the number we
actually want as the highest end.
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So I've got everything in here.
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Now, it should be impossible for
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this test to fail because these, this is
exactly how we're creating the dice.
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It should just work.
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But it's always good to have tests like
this so that if your die creation,
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your whatever your object is, the creation
changes.
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Your tests will warn you about it.
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And then you can either fix your tests or
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you can fix your code, whichever one is
now out of date.
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Okay.
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So I'm not gonna bother with the if name
main thing.
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I'm just gonna run the tests.
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So python -m unittest.
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Ope.
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I need to get into that directory.
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Dice.
There we go.
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Python -m unittest tests.py.
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Ran one test, test was fine.
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All right.
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I also want to test that I can add
multiple dice together.
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So, let's write a quick little test for
that.
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So, def test_add(self) :
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self.assertIsInstance(self.d6+self.d8,
int).
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So what does IsInstance does?
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So, IsInstance is like the IsInstance
function, in,
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the shell, which says tell me if this
variable is an instance of this class.
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Well, assertIsInstance works the same way,
but it's an assertion.
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So run this insertion, make sure that the
first item, this one right here,
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is a member of this class an int or an
instance of this class and end.
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And then we're good, it comes back as
either true or false.
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Okay?
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So let's also before we go any further in
this.
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Let's write some tests for the roll class.
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So, RollTests(unittest.TestCase)
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: I want to make a couple other things
here as well.
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So that they are always around.
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So self.hand1 = dice.Roll('1d2') because
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the smallest die we can have is a
two-sided die.
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And self.hand3 = dice.Roll('3D6') okay.
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So hand one, cause there's one die in it.
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Hand three, cause there's three dice in
it.
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And I want to be able to test the upper
and
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lower boundaries of these total rolls,
right?
4:59
So these are gonna be a lot like the ones
we did on the rock paper scissors game.
5:05
But instead of the greater and less, we're
gonna use assert greater equal or
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assert less equal so that we don't have to
add on that extra number.
5:12
So anyway, let's do test_lower(self) : and
we're going to do
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self.assertGreaterEqual(int(self.hand3),
3).
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Cuz we have three dice.
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The lowest number on each of them is one.
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So the lowest that those three dice can
add up to is three.
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And then let's also do [SOUND]
test_upper(self)
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: self.assertLessEqual(int(self.hand3),
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18) because three six highest dice,
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six is the highest number for each one,
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six plus six plus six is 18, or less if
they're not there.
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So we can do this int call.
6:06
Because we defined the dunder nth method
in our class.
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This is great because if we ever change
our class to where we can't make an nth of
6:13
it, then this is gonna immediately blow
up.
6:17
And we're gonna go, oh, this doesn't work
right.
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Now our class also has a dunder contains
method.
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And our die class has a dunder EQ method
that's defined.
6:28
So we can write a test to make sure that
as given die is inside of a given hand.
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So let's test that out too.
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So let's do test_membership(self) : and we
need to make a couple of things here.
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So let's do our test_die = dice.Die(2) two
sides.
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And test_die.value =
self.hand1.results(0).value so
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we're making a fake die.
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We're giving it the same number as
whatever's in hand one.
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And then we're gonna do
self.assertIn(test_die,
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self.hand1.results) So, we're just making
sure that
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a die with the value of the first or only
die in hand1 is in hand1.
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We're cheating a little bit, but it's
okay.
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There are some ways around this.
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We could do mocking and stuff like that.
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But that's not important at this point.
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Okay, let's run these tests.
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So we come back down here and we run our
tests again.
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All five tests pass, everything's good.
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So this is actually really good.
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It covers most of the functionality in our
two classes that we'd want to test.
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We do have a couple of try accept blocks
we want to test, but
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we'll cover those in the next video.
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I love working with simple assertions like
this.
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They give me a lot more confidence about
what's going on in my code, because I can
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make sure that my collection objects are
holding exactly what I expect them to.
8:04
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