1
00:00:00,040 --> 00:00:03,610
Which is test-first development. The key idea is that any program

2
00:00:03,610 --> 00:00:07,210
feature that doesn't have an automatic test simply does not exist. If

3
00:00:07,210 --> 00:00:09,430
there is a feature, you need to write a test for the

4
00:00:09,430 --> 00:00:13,630
feature before. So, what developers do is to create unit tests for

5
00:00:13,630 --> 00:00:17,420
each such piece of functionality even before the functionality is implemented.

6
00:00:17,420 --> 00:00:19,720
And of course, when you run this test, they will fail. But

7
00:00:19,720 --> 00:00:22,190
the beauty of it is that, as you write your code and

8
00:00:22,190 --> 00:00:25,680
you add more and more fractionality to the feature that you're developing,

9
00:00:25,680 --> 00:00:27,820
these test cases are going to start to pass.

10
00:00:27,820 --> 00:00:30,190
And that's extremely rewarding because it gives you immediate

11
00:00:30,190 --> 00:00:32,530
feedback, again feedback on the fact that you're

12
00:00:32,530 --> 00:00:34,530
developing the code in the right way. As soon

13
00:00:34,530 --> 00:00:37,000
as you write it, you will know. And if you write a piece of code and the

14
00:00:37,000 --> 00:00:38,550
test says still fail, that means that the

15
00:00:38,550 --> 00:00:40,140
code is not doing what it's supposed to do.