I have a test 'works with nested children' within the file fix-order-test.js.
Running the below runs all the tests in the file.
jest fix-order-test
How do I run only a single test? The below does not work as it searches for a file of the regex specified.
jest 'works with nested children'
Running from command line You can run Jest directly from the CLI (if it's globally available in your PATH , e.g. by yarn global add jest or npm install jest --global ) with a variety of useful options. If you'd like to learn more about running jest through the command line, take a look at the Jest CLI Options page.
Jest JavaScript resting framework with a focus on simplicity. Jest was created by Facebook engineers for its React project. Unit testing is a software testing where individual units (components) of a software are tested. The purpose of unit testing is to validate that each unit of the software performs as designed.
From the command line, use the --testNamePattern
or -t
flag:
jest -t 'fix-order-test'
This will only run tests that match the test name pattern you provide. It's in the Jest documentation.
Another way is to run tests in watch mode, jest --watch
, and then press P to filter the tests by typing the test file name or T to run a single test name.
If you have an it
inside of a describe
block, you have to run
jest -t '<describeString> <itString>'
Jest documentation recommends the following:
If a test is failing, one of the first things to check should be whether the test is failing when it's the only test that runs. In Jest it's simple to run only one test - just temporarily change that
test
command to atest.only
test.only('this will be the only test that runs', () => {
expect(true).toBe(false);
});
or
it.only('this will be the only test that runs', () => {
expect(true).toBe(false);
});
Command:
node <path-to-jest> -i <your-test-file> -c <jest-config> -t "<test-block-name>"
<path-to-jest>
:
node_modules\jest\bin\jest.js
node_modules/.bin/jest
-i <you-test-file>
: path to the file with tests (js
or ts
)-c <jest-config>
: path to a separate Jest config file (JSON), if you keep your Jest configuration in package.json
, you don't have to specify this parameter (Jest will find it without your help)-t <the-name-of-test-block>
: actually it's a name (the first parameter) of describe(...)
, it(...)
, or test(...)
block.Example:
describe("math tests", () => {
it("1 + 1 = 2", () => {
expect(1 + 1).toBe(2);
});
it("-1 * -1 !== -1", () => {
expect(-1 * -1).not.toBe(-1);
});
});
So, the command
node node_modules/jest/bin/jest.js -i test/math-tests.js -c test/tests-config.json -t "1 + 1 = 2"
will test it("1 + 1 = 2", ...)
, but if you change the -t
parameter to "math tests"
then it will run both tests from the describe("math tests",...)
block.
Remarks:
node_modules/.bin/jest
with node_modules\jest\bin\jest.js
.'--inspect-brk'
parameter to the command.Having Jest installed, you can simplify the syntax of this command (above) by using NPM scripts. In "package.json"
add a new script to the "scripts"
section:
"scripts": {
"test:math": "jest -i test/my-tests.js -t \"math tests\"",
}
In this case, we use an alias 'jest'
instead of writing the full path to it. Also, we don't specify the configuration file path since we can place it in "package.json"
as well and Jest will look into it by default. Now you can run the command:
npm run test:math
And the "math tests"
block with two tests will be executed. Or, of course, you can specify one particular test by its name.
Another option would be to pull the <the-name-of-test-block>
parameter outside the "test:math"
script and pass it from the NPM command:
package.json:
"scripts": {
"test:math": "jest -i test/my-tests.js -t",
}
Command:
npm run test:math "math tests"
Now you can manage the name of the run test(s) with a much shorter command.
Remarks:
'jest'
command will work with NPM scripts becausenpm makes
"./node_modules/.bin"
the first entry in thePATH
environment variable when running any lifecycle scripts, so this will work fine, even if your program is not globally installed (NPM blog) 2. This approach doesn't seem to allow debugging because Jest is run via its binary/CLI, not vianode
.
If you are using Visual Studio Code you can take advantage of it and run the currently selected test (in the code editor) by pressing the F5 button. To do this, we will need to create a new launch configuration block in the ".vscode/launch.json"
file. In that configuration, we will use predefined variables which are substituted with the appropriate (unfortunately not always) values when running. Of all available we are only interested in these:
${relativeFile}
- the current opened file relative to
${workspaceFolder}
${selectedText}
- the current selected text in the active fileBut before writing out the launch configuration we should add the 'test'
script in our 'package.json'
(if we haven't done it yet).
File package.json:
"scripts": {
"test": "jest"
}
Then we can use it in our launch configuration.
Launch configuration:
{
"type": "node",
"request": "launch",
"name": "Run selected Jest test",
"runtimeExecutable": "npm",
"runtimeArgs": [
"run-script",
"test"
],
"args": [
"--",
"-i",
"${relativeFile}",
"-t",
"${selectedText}"
],
"console": "integratedTerminal",
}
It actually does the same as the commands described earlier in this answer. Now that everything is ready, we can run any test we want without having to rewrite the command parameters manually.
Here's all you need to do:
Select currently created launch config in the debug panel:
Open the file with tests in the code editor and select the name of the test you want to test (without quotation marks):
Press F5 button.
And voilà!
Now to run any test you want. Just open it in the editor, select its name, and press F5.
Unfortunately, it won't be "voilà" on a Windows machines because they substitute (who knows why) the ${relativeFile}
variable with the path having reversed slashes and Jest wouldn't understand such a path.
(In case if the command needs troubleshooting, see similar approach in https://www.basefactor.com/using-visual-studio-code-to-debug-jest-based-unit-tests)
Remarks:
'--inspect-brk'
parameter.'package.json'
.As mentioned in other answers, test.only
merely filters out other tests in the same file. So tests in other files would still run.
So to run a single test, there are two approaches:
Option 1: If your test name is unique, you can enter t
while in watch mode and enter the name of the test you'd like to run.
Option 2:
p
while in watch mode to enter a regex for the filename you'd like to run. (Relevant commands like this are displayed when you run Jest in watch mode).it
to it.only
on the test you'd like to run.With either of the approaches above, Jest will only run the single test in the file you've specified.
If you have jest
running as a script command, something like npm test
, you need to use the following command to make it work:
npm test -- -t "fix order test"
You can also use f
or x
to focus or exclude a test. For example
fit('only this test will run', () => {
expect(true).toBe(false);
});
it('this test will not run', () => {
expect(true).toBe(false);
});
xit('this test will be ignored', () => {
expect(true).toBe(false);
});
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