Mocha Test Explorer for Visual Studio Code

Run your Mocha tests using the Test Explorer UI.

Features

• Shows a Test Explorer in the Test view in VS Code's sidebar with all detected tests and suites and their state
• Adds CodeLenses to your test files for starting and debugging tests
• Adds Gutter decorations to your test files showing the tests' state
• Adds line decorations to the source line where a test failed
• Shows a failed test's log when the test is selected in the explorer
• Lets you choose test suites or individual tests in the explorer that should be run automatically after each file change

Getting started

• Install the extension and restart VS Code
• Put your Mocha command line options (if you have any) in a mocha configuration file (either a .mocharc.* file or a mocha property in your package.json or a mocha.opts file) or VS Code's settings (see below)
• Ensure that your project's root folder is a VS Code root folder. If you are using a "monorepo" architecture (ie. a single repository with multiple projects in separate sub-folders), you may need to add your project sub-folders to VS Code separately. See this article on multi-root workspaces for further details on how to add folders.
• Open the Test view by clicking on the flask icon in the Activity Bar
• Run / Debug your tests using the / icons in the Test Explorer or the CodeLenses in your test file

Using transpilers (Typescript, Babel, etc.)

If you use a transpiler in your project, there are 2 ways to make the tests work in Mocha Test Explorer. The first one is easier to configure, the second one offers better performance (especially in large projects):

• running the original (non-transpiled) sources directly by transpiling them on-the-fly using ts-node for Typescript, babel-register for Babel, etc. Example for Typescript:

  "mochaExplorer.files": "test/**/*.ts",
  "mochaExplorer.require": "ts-node/register"

• enabling source-maps in your transpiler's configuration and running the transpiled test sources using the source-map-support package. Furthermore, you should tell Mocha Test Explorer which files to watch for changes. For example:

  "mochaExplorer.files": "out/test/**/*.js",
  "mochaExplorer.require": "source-map-support/register",
  "mochaExplorer.watch": "out/**/*.js"

  mochaExplorer.watch can be a string, an array of strings or an object with the properties files and optionally ignore and debounce. Make sure that it references the source files of your tests and of the application under test. Watching files consumes system resources, so it shouldn't reference more files than necessary. For this reason, ignore is set to **/node_modules/** by default.

Running VS Code extension tests using vscode-test

Mocha Test Explorer supports running VS Code extension tests using vscode-test: Install the mocha-explorer-launcher-scripts package and add the following settings to your project:

"mochaExplorer.launcherScript": "node_modules/mocha-explorer-launcher-scripts/vscode-test",
"mochaExplorer.autoload": false,
"mochaExplorer.ipcRole": "server",
"mochaExplorer.env": {
  "VSCODE_VERSION": "insiders",
  "ELECTRON_RUN_AS_NODE": null
}

Depending on the structure of your project's tests you may have to add more settings (e.g. mochaExplorer.files, mochaExplorer.ui or mochaExplorer.require). The environment variable VSCODE_VERSION is passed to the runTests() function from the vscode-test package, it specifies the version of VS Code to be used for testing. Note that this needs to be different from the version you're using for development, so if you're using VS Code Insiders, then you must set this variable to "stable".

A sample project for running vscode-test tests using Mocha Test Explorer is available here.

Running tests remotely

If you want/need to run your tests in a remote environment (e.g. in a docker container or on another machine via ssh), you can do so by writing a "launcher script": this script will be called by Mocha Test Explorer (instead of its standard worker script) to load and run the tests in the remote environment. Documentation for writing launcher scripts can be found in the vscode-test-adapter-remoting-util package, which also contains utility functions for writing your launcher script. There are also example projects containing well-documented launcher scripts for running your tests in a docker container or on another machine via ssh.

Alternatively, you can use VS Code Remote Development to move your workspace to the remote environment. If you do so, your tests will also be run in this environment automatically. This is easier to set up (because you don't need to write a launcher script), but requires that your entire workspace and large parts of VS Code run in the remote environment, which (depending on the environment) may be impractical or even impossible.

Configuration

Mocha command line options

You can put any command line options into a mocha configuration file or the legacy mocha.opts file. For mocha.opts, this adapter will use the path test/mocha.opts by default but you can override that with the mochaExplorer.optsFile setting.

Alternatively, you can put supported options into VS Code's settings:

Property	Corresponding command line option
mochaExplorer.ui	-u, --ui (default: "bdd")
mochaExplorer.timeout	-t, --timeout (default: 2000)
mochaExplorer.retries	--retries (default: 0)
mochaExplorer.require	-r, --require (default: [])
mochaExplorer.delay	--delay (default: false)
mochaExplorer.fullTrace	--full-trace (default: false)
mochaExplorer.exit	--exit (default: false)
mochaExplorer.asyncOnly	-A, --async-only (default: false)
mochaExplorer.parallel	-p, --parallel (default: false)
mochaExplorer.jobs	-j, --jobs (default: (number of CPU cores - 1))
mochaExplorer.configFile	--config or --no-config if you set it to null
mochaExplorer.pkgFile	--package or --no-package if you set it to null
mochaExplorer.optsFile	--opts (default: "test/mocha.opts")

Options from VS Code's settings will override those found in a mocha configuration file.

Custom debugger configuration

If you want to customize the configuration used for debugging your tests (e.g. to set sourceMapPathOverrides or skipFiles), you can do so by creating a debugging configuration in your launch.json and setting mochaExplorer.debuggerConfig to the name of your debugging configuration. Here's the default debugging configuration used by this adapter:

{
  "name": "Debug Mocha Tests",
  "type": "pwa-node",
  "request": "attach",
  "port": 9229,
  "continueOnAttach": true,
  "autoAttachChildProcesses": false,
  "resolveSourceMapLocations": [
    "!**/node_modules/**",
    "!**/.vscode/extensions/hbenl.vscode-mocha-test-adapter-*/**"
  ],
  "skipFiles": [
    "<node_internals>/**"
  ]
}

Other options

Property	Description
mochaExplorer.files	The glob(s) describing the location of your test files (relative to the workspace folder) (default: "test/**/*.js"). These globs will be added to the globs found in a mocha configuration file
mochaExplorer.ignore	Glob(s) of files to be ignored (relative to the workspace folder). These globs will be added to the globs found in a mocha configuration file
mochaExplorer.watch	Configure a file watcher. See the section on using transpilers for more details.
mochaExplorer.env	Environment variables to be set when running the tests (e.g. { "NODE_ENV": "production" }). These environment variables will be added to the environment of the process running mocha. To remove an environment variable, set its value to null
mochaExplorer.envPath	Path to a dotenv file (relative to the workspace folder) containing environment variables to be set when running the tests. If you set both mochaExplorer.env and mochaExplorer.envPath, the environment variables will be merged (with those from mochaExplorer.env overriding those from mochaExplorer.envPath)
mochaExplorer.cwd	The working directory where mocha is run (relative to the workspace folder)
mochaExplorer.nodePath	The path to the node executable to use. By default it will attempt to find it on your PATH, if it can't find it or if this option is set to null, it will use the one shipped with VS Code
mochaExplorer.nodeArgv	The arguments to the node executable to use
mochaExplorer.mochaPath	The path to the mocha package to use (absolute or relative to the workspace folder). By default it looks for a directory node_modules/mocha in your workspace and uses that if it exists, otherwise or if this option is set to null, it uses a bundled version of mocha
mochaExplorer.monkeyPatch	Apply a monkey patch to Mocha's bdd, tdd and qunit interfaces to get more accurate line numbers for the tests and suites (default: true)
mochaExplorer.multiFileSuites	Ignore Mocha's idea of which file a test is located in. This is necessary for the worker to find the correct test and error locations when a suite includes tests from other files.
mochaExplorer.debuggerPort	The port to use for debugging sessions (default: 9229)
mochaExplorer.pruneFiles	Only load the test files needed for the current test run (default: false - load all configured files)
mochaExplorer.esmLoader	Use Mocha's experimental ESM module loader if it is available (default: true)
mochaExplorer.globImplementation	The glob implementation to use. \"glob\" (the default) is more compatible, \"vscode\" (the old default) may be faster.
mochaExplorer.launcherScript	The path to a launcher script (relative to the workspace folder) for running your tests remotely
mochaExplorer.ipcRole	Use a TCP connection instead of Node's IPC mechanism for talking to worker processes. This is only needed with some launcher scripts.
mochaExplorer.ipcPort	The TCP port that worker processes use to send their results to VS Code if mochaExplorer.ipcRole is set (default: 9449)
mochaExplorer.ipcHost	The TCP host used for communication with worker processes. If mochaExplorer.ipcRole is set to client, this is the address that Mocha Explorer tries to connect to, if it is set to server, this is the address on which Mocha Explorer will listen for a connection, if it is set to null, Mocha Explorer will listen on all addresses. (default: localhost)
mochaExplorer.ipcTimeout	The timeout in milliseconds for establishing a TCP connection to a worker process if mochaExplorer.ipcRole is set (default: 5000)
mochaExplorer.autoload	Automatically (re)load the tests when source files or relevant settings are changed and/or when VS Code is started (true, false, or "onStart"; default: true)
testExplorer.codeLens	Show a CodeLens above each test or suite for running or debugging the tests
testExplorer.gutterDecoration	Show the state of each test in the editor using Gutter Decorations
testExplorer.onStart	Retire or reset all test states whenever a test run is started
testExplorer.onReload	Retire or reset all test states whenever the test tree is reloaded

Commands

The following commands are available in VS Code's command palette, use the ID to add them to your keyboard shortcuts:

ID	Command
mocha-explorer.enable	Enable Mocha Test Explorer for a workspace folder
mocha-explorer.disable	Disable Mocha Test Explorer for a workspace folder
test-explorer.reload	Reload tests
test-explorer.run-all	Run all tests
test-explorer.run-file	Run tests in current file
test-explorer.run-test-at-cursor	Run the test at the current cursor position
test-explorer.cancel	Cancel running tests

Troubleshooting

If the Test view doesn't show your tests or anything else doesn't work as expected, you can turn on diagnostic logging using one of the following configuration options (note: in multi-root workspaces, these options are always taken from the first workspace folder):

• mochaExplorer.logpanel: Write diagnostic logs to an output panel
• mochaExplorer.logfile: Write diagnostic logs to the given file

Note that the logs usually contain a lot of stacktraces, but if a stacktrace starts with "[INFO] Worker: Looking for <some path> in Error", then that stacktrace doesn't mean that something went wrong: such stacktraces are used to find the location of a test in a file.

There is a bug in Node 10.6.0 - 10.9.0 that breaks this adapter. If you're using a version of Node affected by this bug, add "mochaExplorer.nodePath": null to your configuration as a workaround.

If you think you've found a bug, please file a bug report and attach the diagnostic logs.