Testing Node.js

1. Make sure you have Node.js on your computer.

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

Install Mocha

1. In the embedded Terminal (Alt+F12) , type one of the following commands:

   • npm install mocha for local installation in your project.

   • npm install -g mocha for global installation.

   • npm install --save-dev mocha to install Mocha as a development dependency.

   Learn more from Getting Started on the Mocha official website.

2. Install the Chai expectation library as an efficient replacement for Node.js standard assert function.

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

   npm install --save-dev chai

• Create tests according to the instructions from the Mocha official website.

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.

  

Create a Mocha run configuration

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

2. Specify the Node interpreter to use and the location of the mocha package.

3. 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.

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

5. Specify the tests to run. This can be a specific test or suite, an entire test file, or a folder with test files.

   You can also define patterns to run only the tests from matching files, for example, *.test.js. If the files with tests are stored in a test folder, specify the path to this folder in the pattern relative to the working directory, for example, ./folder1/folder2/test/*.test.js.

6. Choose the interface used in the test to run.

Run tests via a Mocha run configuration

1. Select the Mocha 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. When you select a test in the left-hand pane, the right-hand pane shows the test execution details.

   • Use the Click to see the difference link to open the Difference viewer and compare the actual result with the expectation.

   • The name of file with the selected test is show as a link. Click this link to jump to the source code.

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

   

Rerun failed tests

• In the Test Runner tab, click on the toolbar. PyCharm 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.

  

• Alternatively, click in the gutter next to a failed test and select Run <test name> from the list.

  

See Rerunning tests for details.

• 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, PyCharm 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.

Start debugging a single test from the editor

1. Set a breakpoint in the gutter next to the test you want to debug. You can jump to a failed test by double-clicking it in the Run tool window or by pressing F4.

2. Click or in the gutter and select Debug <test_name> from the list.

3. In the Debug tool window, proceed as usual: step through the program, stop and resume the program execution, examine it when suspended, view actual HTML DOM, run JavaScript code snippets in the Console, and so on. .

Debug test with a Mocha run/debug configuration

1. Set the breakpoints next to the tests that you want to debug. You can jump to a failed test by double-clicking it in the Run tool window or by pressing F4.

2. Create a Mocha run/debug configuration as described above.

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

4. 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 Debugger Console, and so on.

Install nyc

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

  npm install --save-dev nyc

Run tests with coverage

1. Launch the tests:

   • Create a Mocha run/debug configuration as described above, select it from the list on the main toolbar, and click  to the right of the list.

     

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

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

2. Make sure the Docker plugin is 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 the required test framework 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": { "chai": "^4.3.4", "concurrently": "^6.3.0", "eslint": "^8.1.0", "http-server": "^14.0.0", "jest": "^27.3.1", "mocha": "^9.1.3", "nyc": "^15.1.0" } }

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 Mocha official website.

2. 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.