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A lot of the assertions you'll write in your tests have to do with values. You'll want to assert that something is bigger than 5 or has less than 3 items. Let's look at the assertions provided for comparing against numbers.
New Terms
setUp() - Method that is run before each test. Use this to set up state for the tests
assertEqual(x, y) - Make sure x and y are equal
assertNotEqual(x, y) - Make sure x and y are not equal
assertGreater(x, y) - Make sure x is greater than y
assertLess(x, y) - Make sure x is less than y
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[MUSIC]
0:00
All testing libraries work on the idea of
assertions.
0:04
Some call them behaviors, or descriptions,
0:08
and assertions test a condition in your
code that must be met.
0:10
For example,
0:14
when creating a car object, you could test
that the new object has a model name.
0:14
If it doesn't, the assertion fails and we
found an error in our code.
0:19
In Python's unit test framework, we have
quite a few assertions that let you
0:22
test different conditions, like if two
values are equal, an object is
0:25
an instance of a certain class, or if a
certain exception is raised by some code.
0:29
I'll link to the full list of assertions
in the teacher's notes but
0:34
we'll look at the most important ones in
this video and the next couple.
0:37
So, let's get started.
0:40
So, we've already looked at the assert
keyword.
0:42
But the unit test framework,
0:45
unit test module, gives us a bunch of
other assertions that we can use.
0:47
We don't just have to assert that a
statement is true.
0:51
So, let's test the four methods in our
move class using these assertions.
0:55
So, the first one probably the easiest one
is the equality test.
1:00
So we wanna test the dunder eq and
1:08
the dunder ne, which is for equal and not
equal methods.
1:12
But like I said we don't wanna test them
directly.
1:16
So let's say test equal.
1:17
And your methods do have to start with
test.
1:20
If your methods don't start with test they
won't be run as tests.
1:23
So we're gonna say rock1 is equal to rock,
oops, sorry,
1:26
we need to make that moves.Rock.
1:30
And rock2 is equal to moves.rock.
1:33
And we're gonna say self.assertequal rock1
and rock2.
1:36
And then let's test the not equal.
1:43
Test_not_equal and self and we'll say
rock1 or
1:48
rock is equal to moves.Rock and
1:53
we'll say paper is equal to moves.Paper,
and
1:57
then self.assertNotEqual, and rock and
paper,
2:01
because rock and paper should not be equal
to each other.
2:07
But rock and rock, should be.
2:14
This should handle this testing.
2:15
We, we're making the two rock instances.
2:17
We make sure they're equal to each other
and then make a rock instance and
2:19
a paper instance and make sure that they
are not equal to each other.
2:22
We're repeating ourselves a little bit
with making all of these rocks,
2:25
but we'll clean that up later.
2:28
So let's try running these tests.
2:30
So, python tests.py, and, oop, let's make
this a little taller.
2:31
There we go.
2:39
Let's just run it again.
2:41
There we go.
2:43
So, it ran four tests.
2:44
One, two, three, four.
2:45
And they all passed.
2:46
So, great.
Four tests, four passes.
2:48
So now, let's dry up our test a little
bit.
2:50
We can add a method to our test case, and
2:53
I'll leave this up at the top that is
named setUp.
2:55
And this is one of the fun cases where a
library predates PEP 8.
3:01
So setUp has camel case, PEP 8 says we
should be lowercase with underscores but
3:05
it's old, so it stays just like it is.
3:11
Okay, so this function, this method will
get called,
3:14
will get run before each of our tests.
3:19
So, any code we put in here will always
have like, kinda a fresh state.
3:21
So what we're gonna do is say, self.rock
is equal to
3:26
moves.Rock, self.paper is equal to
moves.Paper,
3:31
and self.scissors is equal to
moves.Scissors.
3:36
And now I wish I had written something
about Jagger,
3:41
because then I would have had
moves.Jagger.
3:44
Okay.
3:47
Now Python has to do a little bit more
work here.
3:48
Python has to instantiate these variables
every time.
3:49
But we get to write less code and really
that's what's important, right?
3:52
Our workload?
3:55
Okay.
3:57
So we have these three attributes.
3:58
We have self.rock, self.paper,
self.scissors.
3:59
Let's use them.
4:02
So here we're gonna do rock one.
4:03
We don't need rock one, we don't need rock
one at all.
4:05
And we don't even need rock two.
4:08
So we're gonna take those out.
4:09
And we're gonna assert that self.rock is
equal to a new rock instance.
4:11
And then here we can take these two out
completely and
4:19
just assert that self.rock is not equal to
self.paper, 'kay?
4:23
So, we've dried the stuff up a whole lot.
4:30
Now, we have to make the new rock instance
here,
4:32
because we don't want to just test that
the object is equal to itself.
4:34
We know the object is equal to itself.
4:37
We wanna make sure the object is equal to
another instance of the same class,
4:39
because two rocks with the same, this
should be tied.
4:43
So we save all that, we run our tests
again, and
4:46
oh, I have a typo, this should be
moves.Rock.
4:51
All right, one more time?
4:54
And we're all good.
4:57
All the tests are still passing.
4:59
Okay, to complete the testing of all of
our moves,
5:00
we should test our greater than, or the
dunder vt, and
5:04
our less than, or the dunder le methods.
5:09
So, let's test that rock is better than
scissors, because it should be.
5:13
So, self.assertGreater,
5:21
self.rock, and self.scissors.
5:24
And let's also test that paper is worse
than scissors.
5:29
So, self.assertLess,
5:37
self.paper, and self.scissors.
5:41
Okay.
5:46
So, we're trying to write these in a, a
fairly human readable way.
5:47
So let's, let's test this.
5:52
All of our tests pass, and that's great.
5:55
Now, there are a lot more search engines
that are available.
5:57
We're gonna cover a few more in the
course, and
5:59
the rest I'm gonna make sure and link to
in the teacher's notes.
6:01
So, be able to read those and you'll be
able to test all sorts of things.
6:04
Assertions that deal with quantitative
values like assertEqual or
6:08
assertGreater are really handy when you're
dealing with numbers.
6:11
I know that I use them quite a bit, both
in regular scripts and for
6:14
testing web apps.
6:18
Or I wanna make sure that a status code is
200, 304, 404, or something else.
6:19
Remember, you have the full power of
Python too, so feel free to use len and
6:24
other functions in your assertions.
6:29
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