# Testing components using Jest

The page provides instructions for testing components using Jest.

## Running Jest tests

CT5 uses [Jest](https://jestjs.io/) to run unit tests. Each CT5 component directory includes a `__tests__` directory for unit tests.

To run unit tests for all components in your application, execute the command below from the root directory of your application:

```
$ yarn test
```

## Debugging Jest tests

You can debug [Jest](https://jestjs.io/) tests using Google Chrome, IntelliJ IDEA, or Visual Studio Code.

### Debug using Google Chrome Developer Tools

To debug application tests using Google Chrome Developer Tools, follow the steps below:

1. From the root directory of your application, run the command below:

   ```
   $ yarn run test:debug
   ```

   The command outputs a chrome-devtools:// URL
2. Open Google Chrome. Paste the chrome-devtools:// URL into the address bar, or navigate to chrome://inspect and select your app.

**📌 NOTE**\
The `test:debug` script uses the `--inspect-brk` option to start the Node.js Inspector. If the `test:debug` script fails for you, then edit your application’s `packages.json` file and use the alternative definition for the `test:debug` script below:

```json
"scripts": {
    ⋮
    "test:debug": "node --inspect --debug-brk ./node_modules/jest-cli/bin/jest.js -i --env jest-environment-node-debug"
    ⋮
}
```

### Debug using IntelliJ IDEA

To debug application tests using IntelliJ IDEA, follow the steps below:

1. Install the Node.js plugin from the JetBrains plugin repository
2. Click **Run > Debug > Edit Configurations**
3. Click **+ > Jest**
4. Configure the following options:

   | Option | Value |
   | --- | --- |
   | Jest package | the path to the `node_modules/jest-cli` directory in your CT5 application directory |
   | Working directory | the path to your CT5 application directory |
   | Jest options | `--runInBand` |

### Debug using Visual Studio Code

To debug application tests using Microsoft Visual Studio Code, follow the steps below:

1. Click **File > Open Folder** and open the directory of your CT5 application
2. Click **Debug > Run Configurations**
3. If prompted to select an environment, select **Node.js**
4. From the list of possible run configurations, select **Launch Program**
5. Edit the Launch Program configuration:

   ```json
   {
       "type": "node",
       "request": "launch",
       "name": "Debug Jest tests",
       "program": "${workspaceRoot}/node_modules/jest-cli/bin/jest.js",
       "args": "--runInBand"
   }
   ```
6. Click **Debug > Start Debugging**