Mocha breakpoints using Visual Studio Code

Question

Is it possible to add breakpoints to ones Mocha tests using Visual Studio Code?

Normally when debugging code one need to configure the launch.json, setting the prog

Answer 1

If you have some dependency in the test it is also easy to attach it.

For example, I am using mongo-unit-helper to also have unit tests integrated with Database.

package.json script is: mocha --recursive --require ./test/mongo-unit-helper.js --exit"

My launch.json looks like:

  "configurations": [
  {
  "type": "node",
  "request": "launch",
  "name": "Mocha Tests",
  "program": "${workspaceFolder}/node_modules/mocha/bin/_mocha",
  "args": [
    "-u",
    "tdd",
    "--timeout",
    "999999",
    "--colors",
    "--recursive",
    "--require",
    "${workspaceFolder}/test/mongo-unit-helper.js",
    "${workspaceFolder}/test/**/*.js",
  ],
  "internalConsoleOptions": "openOnSessionStart"
 }
]

Solution is to put --require separately in args in launch.json.

Answer 2

The way I got it to work on VS Code (1.8.2) on Mac OS X is:

{
    "name": "Mocha",
    "type": "node",
    "request": "launch",
    "program": "${workspaceRoot}/node_modules/mocha/bin/_mocha",
    "stopOnEntry": false,
    "args": ["--recursive"], //you can specify paths to specific tests here
    "cwd": "${workspaceRoot}",
    "runtimeExecutable": null,
    "env": {
        "NODE_ENV": "testing"
    }
}

Mocha needs to be installed in the npm modules directory.

Answer 3

1) Go to

.vscode

then

launch.json

file

2) Add the following configuration in launch.json -

{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "node",
            "request": "launch",
            "name": "Mocha Test",
            "cwd": "${workspaceRoot}",
            "runtimeExecutable": "${workspaceRoot}/*folder_path_containing_test*/node_modules/.bin/mocha",
            "windows": {
                "runtimeExecutable": "${workspaceRoot}/*folder_path_containing_test*/node_modules/.bin/mocha.cmd"
            },
            "runtimeArgs": [
                "--colors",
                "--recursive",
                "${workspaceRoot}/*folder_path_till_test*/tests"
            ],
            "internalConsoleOptions": "openOnSessionStart"
        },
        {
            "type": "node",
            "request": "launch",
            "name": "Launch Program",
            "program": "${workspaceRoot}/*folder_path_to_test*/app.js"
        }
    ]
}

3) Set breakpoints in test file and then press F5

Answer 4

If you add ${file} variable at the end of the args list you can start debugging directly from the file you have open:

        {
            "type": "node",
            "request": "launch",
            "name": "Mocha Tests",
            "program": "${workspaceFolder}/node_modules/mocha/bin/_mocha",
            "args": [
                "-u",
                "tdd",
                "--timeout",
                "999999",
                "--colors",
                "${file}"
            ],
            "internalConsoleOptions": "openOnSessionStart"
        }

Answer 5

Here is an example of launch configuration (launch.json) from Microsoft, which works with Mocha and allows using the debugger.

Also, there is a description of how to use the --debug-brk option.

Finally, here is an alternative version of how to debug code with Mocha tests using tasks.json file of VS Code and Gulp task runner.

Answer 6

Another way is to use the --debug-brk command line option of mocha and the default Attach launch setting of the Visual Studio Code debugger.

---

Suggested deeper explanation (from André)

To do this:

Run mocha from the command line using this command:

mocha --debug-brk

Now in VS Code click on the Debug icon, then select Attach from the option next to the start button. Add breakpoints in VS Code and then click start.