Run only ONE test with Jest
JavascriptUnit TestingJestjsJavascript Problem Overview
I want to run just one test with Jest.
I use it.only or describe.only, but it still runs a whole lot of tests. I think it runs all the tests since my last commit, but it shouldn't have this behavior with the only flag explicitly set, right?
What causes this behavior and how can I run a single test?
Javascript Solutions
Solution 1 - Javascript
> Jest parallelizes test runs and it doesn't know upfront which tests it > should run and which it shouldn't run. > This means when you use "fit", it will only run one test in that file. > But it still runs all other test files in your project.
fit, fdescribe and it.only, describe.only have the same purpose: skip other tests and run only me.
Source: https://github.com/facebook/jest/issues/698#issuecomment-177673281
Use the Jest filtering mechanism. When you run your tests like,
jest --config=jest.config.json --watch
you can filter tests by a testname or filename. Just follow the instructions in the terminal.
Press p, and then type a filename.
Then you can use describe.only and it.only which will skip all other tests from the filtered, tested file.
Solution 2 - Javascript
it.only and describe.only work only for the module they are in. If you are having problems to filter tests in multiple files, you can use jest -t name-of-spec, filtering tests that match the specified name (match against the name in describe or test).
Source: Jest CLI Options
For example, I focus the test which I'm currently writing like this (with the test script in the package.json):
npm test -- -t "test foo"
Solution 3 - Javascript
For me it works if I use two parameters like this:
yarn test --watch -f "src/...fullpath.../reducer.spec.js" -t "Name of the test"
Flags:
--watch: is optional
-f: will do filtering of your files, so if you have a lot of tests with the same name, specify the full path to the exact file
-t: works with 'describe' name or 'it' name of your test
Solution 4 - Javascript
It's like this:
jest sometest.test.js -t "some expression to match a describe or a test"
It will test all files with the name sometest.test.js and matching based on -t option. If you only want to test a specific file, you can do this:
jest src/user/.../sometest.test.js
Solution 5 - Javascript
Trying to enter the full path results on 0 matches to that pattern, even though the file exists and has a couple of assertions.