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JavaScript Unit Testing

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Outlining Your Test Suite

4:31 with Guil Hernandez and Joseph Fraley

A nice feature of Mocha is that we can outline tests that need to be written before we’re ready to write them. So when you have an idea for a test, but you aren’t yet sure what it will look like, you can still communicate your idea to other developers and get started.

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  • To mark a test as “pending”, do not add a function as a second argument
  • You can also mark tests as "pending" by typing an x in front of the pending block, like xdescribe() or xit()
  • Adding an x in front of the describe() block marks all of the specs inside as "pending"

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    In some ways being a programmer is more like being a writer 0:00
    than being an engineer. 0:03
    It requires a lot of creativity and you can get stuck a lot waiting for 0:05
    inspiration to strike. 0:09
    A nice feature of Mocha is that we can outline tests 0:11
    that need to be written still before we're ready to write them. 0:14
    So when you have an idea for a test but you don't have time to figure it out, or 0:17
    you aren't yet sure what it will look like, 0:22
    you can still communicate your idea to other people and get started. 0:24
    Let me show you an example. 0:28
    In order to play a game, it would be nice to have a function 0:30
    that checks whether the game is over after each turn. 0:33
    That way, every time I make a guess, the game engine will check and 0:36
    see whether I've struck the last ship in one or 0:39
    whether the next player should start their turn. 0:42
    I know I need that, but I'm not ready to think about how it works yet, 0:44
    not even to write the tests. 0:48
    So I can write a pending test spec to keep track of those tests I have to 0:50
    write later. 0:53
    Inside the test folder I'll create a new test suite file called gametest.js 0:54
    since this suite will focus on functions pertaining to the flow of the game. 1:00
    So first I'll import chai at the top of the new file so 1:08
    that we can use it here as an expectation. 1:12
    And now I'll set up the fundamental describe block for the suite. 1:23
    And as the first argument I'll write, GAME INSTANCE FUNCTIONS in all caps. 1:36
    This is only here to make the output nicer for me. 1:42
    I'll call the function I'm testing here, checkGameStatus. 1:47
    So I'll create a new test suite for it. 1:50
    Now, a test spec that I know I should write for 2:08
    this function confirms that it should tell me when the game is over. 2:11
    So I'll create a new spec that says, it should tell me when the game is over. 2:15
    This is a pending test, so in order to mark this test as pending, 2:26
    I do not add a function as the second argument. 2:30
    The it block is only written with the first argument describing the test. 2:34
    And it doesn't contain any expectations yet. 2:39
    So now if I go over to the console and run npm test, 2:42
    It showed me that I now have 15 tests passing and one pending. 2:50
    Notice the pending test is in a different color so they're easier to see. 2:56
    In my console the test is light blue. 3:01
    This is really useful as a reminder to myself and 3:08
    others that some tests need to be written still. 3:10
    It's like having an outline for my outline. 3:13
    It communicates some information for getting started. 3:15
    I can also mark tests as pending by typing an x in front of the pending block. 3:22
    Like, xdescribe, 3:27
    or, xit. 3:33
    For example, if I add a regular test spec to my current suite, 3:44
    even though I've added a function as a second argument, 3:50
    I can add x in front of the describe block, and 3:55
    all of the specs inside will be marked as pending. 4:00
    I prefer leaving out a callback to using xdescribe, 4:16
    because I don't have to delete anything later. 4:20
    I just have to continue writing the test spec as I normally would. 4:23
    You might see this done both ways, so 4:27
    feel free to use whichever method you like better. 4:29

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