1
00:00:05,850 --> 00:00:12,420
I started off with creating a new library directory and like all of my other examples, let's keep this

2
00:00:12,420 --> 00:00:16,080
simple and just see the important aspects of what we are working on.

3
00:00:16,990 --> 00:00:22,660
So let's start off with the default example that Rust gives us and let's break it down really quickly.

4
00:00:22,750 --> 00:00:30,430
So at the very top, we see we have cfg test C CFG stands for configuration and tells us to only include

5
00:00:30,430 --> 00:00:33,880
the following when given a certain configuration option.

6
00:00:33,940 --> 00:00:39,040
So we are essentially configuring the following only for when we want to run test.

7
00:00:39,430 --> 00:00:43,600
Then we create a test module and we add this bit.

8
00:00:45,150 --> 00:00:45,960
Right here.

9
00:00:46,050 --> 00:00:51,390
And what this is going to do is it's basically going to tell the rest compiler, hey, the following

10
00:00:51,390 --> 00:00:57,060
function is a test and I'll show what happens when we forget that little bit right there.

11
00:00:58,440 --> 00:01:06,690
And then inside of that, we have the the test function and we have many options that we can choose

12
00:01:06,690 --> 00:01:12,630
from and we can see in the default example, it has the assert equals macro.

13
00:01:12,930 --> 00:01:18,670
And this is going to make sure that the left hand side is going to equal the right hand side.

14
00:01:18,690 --> 00:01:26,940
So to run this, we simply run cargo test and we concede that it outputs running one test and it is

15
00:01:26,940 --> 00:01:27,960
testing.

16
00:01:28,760 --> 00:01:30,950
It works, which is the name of our function.

17
00:01:30,950 --> 00:01:32,450
And in this case it passed.

18
00:01:32,450 --> 00:01:34,580
So it outputs okay to us.

19
00:01:35,740 --> 00:01:38,860
And it lets us know that we had one that passed.

20
00:01:40,130 --> 00:01:46,700
So what happens if we take this little porch portion out that I mentioned earlier and now we try to

21
00:01:46,700 --> 00:01:47,270
run it?

22
00:01:49,730 --> 00:01:51,970
Well, it says it's running zero test.

23
00:01:51,980 --> 00:01:52,280
Right.

24
00:01:52,280 --> 00:01:55,490
So now the rest compiler doesn't know that this is.

25
00:01:55,760 --> 00:02:01,070
So that's why that little bit is important to include above the function.

26
00:02:02,370 --> 00:02:06,080
So we can see that everything worked.

27
00:02:06,090 --> 00:02:10,440
So let's add another function and make it a failing one just to see what that looks like.

28
00:02:11,430 --> 00:02:14,810
And we can do this by using the panic keyword.

29
00:02:14,820 --> 00:02:20,490
So remember, we've got to include test and then we're going to say function.

30
00:02:20,640 --> 00:02:21,750
It fails.

31
00:02:23,470 --> 00:02:25,120
And now we're going to just say.

32
00:02:26,140 --> 00:02:26,950
Panic

33
00:02:29,440 --> 00:02:30,490
test failed.

34
00:02:32,710 --> 00:02:35,920
And now if we run this running cargo test.

35
00:02:37,020 --> 00:02:39,630
We now see what a failing test looks like.

36
00:02:39,630 --> 00:02:42,450
So again, it's going to tell us what function was ran.

37
00:02:42,450 --> 00:02:43,170
In this case.

38
00:02:43,400 --> 00:02:48,210
It fails and it failed, which is great because that's what we wanted to see.

39
00:02:48,240 --> 00:02:51,660
We just wanted to see what a failing test looks like.

40
00:02:52,430 --> 00:02:58,820
And we can use panic to induce a failing test in this situation.

41
00:02:59,240 --> 00:03:01,970
So that's just a very broad overview of testing.

42
00:03:01,970 --> 00:03:07,940
So let's get into a little bit more examples using annotations in the next lecture.