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