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What is Code Coverage?

1:53 with Andrew Chalkley

In this video we'll look what code coverage is, why you should use it and what it _doesn't_ do.

Resources

  • 0:00

    [MUSIC]

  • 0:04

    Hello world.

  • 0:05

    Andrew here, JavaScript developer, lifelong learner and

  • 0:08

    teacher here at Treehouse.

  • 0:10

    In this workshop, we're going to be talking about code coverage.

  • 0:14

    Code coverage is the healthy development practice that describes how

  • 0:18

    much of a program source code is executed during the execution of the test sweep.

  • 0:23

    So, why should you do code coverage?

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    Well, it helps to see how much testing you're doing in your project.

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    It helps you spot parts in your code that the tests are missing.

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    It's also good to show business stakeholders in a project,

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    whether they are a project manager or clients on a project.

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    If you're publishing NPM modules,

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    showing your code coverage gives developers confidence in your module.

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    For example, you'd expect a module with 100% code coverage

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    should work better than a module with only 10%.

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    While software with more code coverage may instill more confidence than software

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    without code coverage,

  • 1:00

    it doesn't guarantee the quality of the tests that test the source code.

  • 1:04

    For example, there may be sets in edge cases missing.

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    Because test edge cases could be missing,

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    there could be some bugs that could still happen.

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    In other words, having 100% code coverage doesn't ensure good software.

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    The till we'll be using for code coverage is called Istanbul.

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    Istanbul is a node module that's compatible with testing libraries

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    like Mocha and Jasmine.

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    Istanbul can generate code coverage reports that are compatible with

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    online services like Coveralls and Codecov.

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    You can share your open source projects code coverage publicly, or

  • 1:40

    your internal or client projects privately.

  • 1:44

    In this workshop, we're going to set up code coverage in a simple calculator app.

  • 1:48

    Feel free to clone the app now or download the zip file attached to this video.

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