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Code Coverage with Istanbul

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Setting Up Istanbul

3:21 with Andrew Chalkley

In this video we'll set up Istanbul in a simple calculator project.

Resources

Code Downloads

git clone https://github.com/treehouse-projects/calculator.js-code-coverage calculator.js

Commands

npm install istanbul --save-dev

./node_modules/.bin/istanbul cover ./node_modules/.bin/_mocha

If you're using a more complex testing directory with sub-folders you should use the recursive flag like this:

./node_modules/.bin/istanbul cover ./node_modules/.bin/_mocha -- -recursive

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    If you haven't cleared the repository, 0:00
    do that now or download the zip file with this video. 0:02
    Change into the directory and install the current development dependencies. 0:15
    Npm install should install the testing framework Mocha and 0:23
    the assertion library Chai. 0:27
    The calculative functionality is in the index.js file. 0:32
    There's functions for addition, subtraction. 0:39
    Division and multiplication, they're all exported at the bottom here. 0:43
    Mocha is being called from the package.json file. 0:52
    So we can run npm test. 0:55
    There's currently three pending tests for the multiplication function. 1:03
    Let's install Istanbul as a developer dependency. 1:08
    To run Istanbul, 1:22
    you can run the Istanbul binary 1:25
    followed by the cover argument. 1:30
    And the mocha binary. 1:39
    You have to use the _mocha file because the mocha binary folks and 1:42
    executes this under the hood. 1:47
    This way Istanbul can hook into the underlying code. 1:49
    A link in the teacher's note covers the GitHub issue that 1:53
    covers why you'd want to include the _mocha rather than mocha. 1:56
    Once you've run Istanbul, 2:01
    if you look in the root of the folder, you'll see a coverage directory. 2:03
    And the coverage folder is where HTML reports are. 2:09
    Now that we know that the Istanbul binary works, 2:12
    let's modify the package.json file to have a coverage task. 2:15
    I'm going to call this task test:coverage. 2:21
    This is because I'm still running the tests, but with the coverage. 2:30
    We don't need to include the full binary paths for 2:37
    each executable since NPM knows where the binaries are. 2:39
    So we can write the tasks simply by saying, istanbul cover _marker. 2:44
    Save the package.json file and then go back to the terminal to see if it works. 2:50
    Awesome, it does work. 3:04
    Finally, you don't want to check your coverage into version control. 3:08
    You can modify the .gitignore file to include the coverage directory too. 3:12
    In the next video, we'll take a look at the report. 3:18

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