Jest Code Coverage

When using Jest 21.2.1, I can see code coverage at the command line and create a coverage directory by passing --coverage to the Jest script. Below are some examples I tend to install Jest locally, in which case the command might look like this npx jest --coverage. I assume though haven't confirmed, that this would also work if I installed Jest globally

bail number boolean . Default 0 By default, Jest runs all tests and produces all errors into the console upon completion. The bail config option can be used here to have Jest stop running tests after n failures. Setting bail to true is the same as setting bail to 1.. cacheDirectory string . Default quottmpltpathgtquot The directory where Jest should store its cached dependency information.

How to track untested files with Jest's code coverage report. By default, Jest will calculate coverage for each file that has a test and any files that they are importing. This means that if you had the following files Foo.js Foo.test.js tests the code from Foo.js Bar.js Even though Bar.js doesn't have any unit tests, this won't

Excluding untestable code-sections from the coverage stats. Despite all attempts you might end up in not finding a feasible or quotaffordablequot test case for every line of code. To keep your coverage stats clean and meaningful anyways, Jest provides a way to explicitly exclude code sections from the coverage stats.

To run code coverage, we'll add the --coverage flag to our Jest command jest --coverage. This will generate a coverage report in the coverage directory. Code Coverage Report. The code coverage report will show us the percentage of code covered by our tests. In this case, we've covered all the code in our example.js file quotstatementquot 100

Code coverage configuration matters, here's why Configuring a coverage threshold Conclusion If there is something that should be never overlooked in any project, be it JavaScript or any other language, that's code coverage. In this brief tutorial we see how to configure code coverage in Jest, the popular testing framework for JavaScript.

We have three ways to produce a code coverage report Cobertura Jenkins Plugin a utility for code coverage that will collect the report from Jest Jest-JUnit Exports the Jest code coverage report to XML formatted as a Java JUnit report Plain HTML exports the code coverage report as an IstanbulJS-formatted HTML

Leverage Jest's built-in coverage tool to set minimum coverage thresholds, find parts of the code that aren't tested and how to disable it in specific cases. Introduction. Jest is a batteries-included framework with best-practices, a test runner, CLI, assertion library, stubbing library, module mocking library and coverage built-in.

Lines Coverage The percentage of lines of code that have been executed. These metrics help you understand which parts of your code are well-tested and which parts need more attention. Run Jest with Coverage Add the --coverage flag to your test command in the CI configuration file.

Jest, comes with a built-in coverage report to show how well your code is being tested. It's a handy tool for seeing what's covered and what still needs testing, but it can be a little tricky