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JavaScript Unit Testing

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Different Types of Testing

3:16 with Guil Hernandez and Joseph Fraley

We can test many aspects of our software, from a single function’s return value, to complete user stories. In this video we’ll narrow in on the kind of testing we’ll do most: unit testing.

The kind of automated test we'll learn to write in this course 0:00
are called, Unit Tests. 0:03
Unit Testing involves Writing tests that confirm an individual function or 0:05
piece of code works the way we want it to. 0:10
We write Unit Test for code that has a clear specific purpose, for example, 0:13
we'll often write unit test for the individual functions in a program, 0:18
the unit tests can then call the function without needing to run our entire 0:22
application to make sure we know that the function behaves as we expect. 0:26
Unit Tests are kind of like a basketball drill. 0:31
As a basketball player, you need to master various skills like shooting, 0:34
passing, running, dribbling and so on. 0:38
Basketball players run specific drills to test 0:41
each of these skills outside of an actual game. 0:44
A basketball player might just practice free throws for a while and 0:47
then practice dribbling at a different time without worrying about shooting or 0:51
passing or what their teammates are doing. 0:55
A Unit Test is like one of these drills and 0:58
we can run unit tests constantly during our development process 1:00
to ensure that everything is working every time we make a change. 1:04
But being good at each single thing isn't enough to be 1:08
a really good basketball player. 1:11
They also have to be able to do them all together. 1:13
In addition to practicing each individual basketball skill, 1:16
players practice drills as a team. 1:19
They need to make sure that they can dribble, pass, and 1:21
shoot just as well when there are other people doing their part around them. 1:24
And that they can do them all together in the correct sequence. 1:29
In programming this kind of testing is called Integration Testing. 1:33
You use integration tests when you add new code to preexisting code 1:36
to make sure that not only do all of the pieces work individually as expected, but 1:41
also that they run together correctly without breaking. 1:45
Product managers or people who run open-source projects might also run 1:49
integration tests whenever others write code to contribute to their projects. 1:53
To make sure that the code others write doesn't break their existing project 1:58
that's useful. 2:02
On a basketball team it's not enough that your skills are up to par. 2:03
And that you work well together as a team. 2:07
You also have to play actual games. 2:09
Live games are very different even from practice games, 2:12
we play basketball on different courts. 2:16
With different crowds and against teams with different strategies. 2:18
So being a good basketball team requires a lot of team experience in this context. 2:22
In software, this kind of testing is called End-To-End Testing. 2:29
We fire up the application and 2:33
run it from start to finish for all the user stories we can think of. 2:34
This ensures that the program is ready to go live. 2:38
And that the special details of deployment don't screw up the stuff that we 2:41
carefully tested on our local machines with Unit Test and integration tests. 2:46
We conduct end to end test very occasionally. 2:51
Maybe only a few times during a product's life cycle. 2:53
As a very time consuming and expensive. 2:56
You might conduct some or all of these kind of tests where you work or 2:59
in your personal projects. 3:03
We'll focus on Unit Testing in this course because that's what you'll spend most of 3:04
the time writing. 3:08
Unit Tests actually help us write better code and 3:10
grow as developers as soon as we start using them. 3:13