Jest

• In the embedded Terminal (Alt+F12) , type:

  npm install --save-dev jest

To run a single test from the editor

• Click or in the gutter and select Run <test_name> from the list.

  

  You can also see whether a test has passed or failed right in the editor, thanks to the test status icons and in the gutter.

To create a Jest run configuration

1. Open the Run/Debug Configuration dialog (Run | Edit Configurations on the main menu), click in the left-hand pane, and select Jest from the list. The Run/Debug Configuration: Jest dialog opens.

2. Specify the Node.js interpreter to use. This can be a local Node.js interpreter or a Node.js on Windows Subsystem for Linux.

3. Specify the location of the jest, react-scripts, react-script-ts, react-super-scripts, or react-awesome-scripts package.

4. Specify the working directory of the application. By default, the Working directory field shows the project root folder. To change this predefined setting, specify the path to the desired folder or choose a previously used folder from the list.

5. Optionally specify the jest.config file to use: select the relevant file from the list, or click and select it in the dialog that opens, or just type the path in the field. If the field is empty, IntelliJ IDEA looks for a package.json file with a jest key. The search is performed in the file system upwards from the working directory. If no appropriate package.json file is found, then a Jest default configuration is generated on the fly.

6. Optionally configure rerunning the tests automatically on changes in the related source files. To do that, add the --watch flag in the Jest options field.

To run tests via a run configuration

1. Select the Jest run/debug configuration from the list on the main toolbar and click  to the right of the list.

2. The test server starts automatically without any steps from your side. View and analyze messages from the test server in the Run tool window.

3. Monitor test execution and analyze test results in the Test Runner tab of the Run tool window, see Explore test results for details.

To rerun failed tests

• In the Test Runner tab, click on the toolbar. IntelliJ IDEA will execute all the tests that failed during the previous session.

• To rerun a specific failed test, select Run <test name> on its context menu.

• To jump between a test and its subject or vice versa, open the file in the editor and select Go to | Test or Go to | Test Subject from the context menu, or just press Ctrl+Shift+T.

• To jump from a test result to the test definition, click the test name in the Test Runner tab twice, or select Jump to Source from the context menu, or just press F4. The test file opens in the editor with the cursor placed at the test definition.

• For failed tests, IntelliJ IDEA brings you to the failure line in the test from the stack trace. If the exact line is not in the stack trace, you will be taken to the test definition.

  

• To start debugging a single test from the editor, click or in the gutter and select Debug <test_name> from the list.

• To launch test debugging via a run/debug configuration, create a Jest run/debug configuration as described above. Then select the Jest run/debug configuration from the list on the main toolbar and click  to the right of the list.

In the Debug tool window that opens, proceed as usual: step through the tests, stop and resume test execution, examine the test when suspended, run JavaScript code snippets in the Console, and so on.

To run tests with coverage

1. Create a Jest run/debug configuration as described above.

2. Select the Jest run/debug configuration from the list on the main toolbar and click  to the right of the list.

   Alternatively, quickly run a specific suite or a test with coverage from the editor: click or in the gutter and select Run <test_name> with Coverage from the list.

   

3. Monitor the code coverage in the Coverage tool window. The report shows how many files were covered with tests and the percentage of covered lines in them. From the report you can jump to the file and see what lines were covered – marked green – and what lines were not covered – marked red:

   

Before you start

1. Install and enable the Node.js Remote Interpreter plugin on the Settings/Preferences | Plugins page, tab Marketplace, as described in Installing plugins from JetBrains repository.

2. Make sure the Node.js and Docker required plugins are enabled on the Settings/Preferences | Plugins page, tab Installed, see Managing plugins for details.

3. Download, install, and configure Docker as described in Docker

4. Configure a Node.js remote interpreter in Docker or via Docker Compose and set it as default in your project. Also make sure the package manager associated with this remote interpreter is set as project default.

5. Open your package.json and make sure Jest is listed in the devDependencies section:

   { "name": "node-express", "version": "0.0.0", "private": true, "dependencies": { "cookie-parser": "~1.4.4", "debug": "~2.6.9", "express": "~4.16.1", "http-errors": "~1.6.3", "morgan": "~1.9.1", "pug": "^3.0.2" }, "devDependencies": { "eslint": "^8.1.0", "http-server": "^14.0.0", "jest": "^27.3.1" } }

6. Right-click anywhere in the editor and select Run '<package manager> install' from the context menu.

Run tests

1. Create tests according to the instructions from the Jest official website.

2. Mark the folder where the unit tests are stored as a test source folder, see Content roots.

3. Proceed as with local development: run and debug single tests right from the editor or create a run/debug configuration to launch some or all of your tests as described in Run tests and Debug tests above.