What is Code Coverage?

[MUSIC] 0:00 Hello world. 0:04 Andrew here, JavaScript developer, lifelong learner and 0:05 teacher here at Treehouse. 0:08 In this workshop, we're going to be talking about code coverage. 0:10 Code coverage is the healthy development practice that describes how 0:14 much of a program source code is executed during the execution of the test sweep. 0:18 So, why should you do code coverage? 0:23 Well, it helps to see how much testing you're doing in your project. 0:26 It helps you spot parts in your code that the tests are missing. 0:29 It's also good to show business stakeholders in a project, 0:33 whether they are a project manager or clients on a project. 0:36 If you're publishing NPM modules, 0:40 showing your code coverage gives developers confidence in your module. 0:43 For example, you'd expect a module with 100% code coverage 0:47 should work better than a module with only 10%. 0:51 While software with more code coverage may instill more confidence than software 0:54 without code coverage, 0:58 it doesn't guarantee the quality of the tests that test the source code. 1:00 For example, there may be sets in edge cases missing. 1:04 Because test edge cases could be missing, 1:08 there could be some bugs that could still happen. 1:10 In other words, having 100% code coverage doesn't ensure good software. 1:14 The till we'll be using for code coverage is called Istanbul. 1:20 Istanbul is a node module that's compatible with testing libraries 1:24 like Mocha and Jasmine. 1:27 Istanbul can generate code coverage reports that are compatible with 1:29 online services like Coveralls and Codecov. 1:32 You can share your open source projects code coverage publicly, or 1:37 your internal or client projects privately. 1:40 In this workshop, we're going to set up code coverage in a simple calculator app. 1:44 Feel free to clone the app now or download the zip file attached to this video. 1:48