Debugging

This guide shows you how to debug your Workers tests with Vitest. This is available with @cloudflare/vitest-pool-workers v0.7.5 or later.

Open inspector with Vitest

To start debugging, run Vitest with the following command and attach a debugger to port 9229:

vitest --inspect --no-file-parallelism

Customize the inspector port

By default, the inspector will be opened on port 9229. If you need to use a different port (for example, 3456), you can run the following command:

vitest --inspect=3456 --no-file-parallelism

Alternatively, you can define it in your Vitest configuration file:

import { cloudflareTest } from "@cloudflare/vitest-pool-workers";
import { defineConfig } from "vitest/config";

export default defineConfig({
	plugins: [
		cloudflareTest({
			// ...
		}),
	],
	test: {
		inspector: {
			port: 3456,
		},
	},
});

Setup VS Code to use breakpoints

To setup VS Code for breakpoint debugging in your Worker tests, create a .vscode/launch.json file that contains the following configuration:

{
	"configurations": [
		{
			"type": "node",
			"request": "launch",
			"name": "Open inspector with Vitest",
			"program": "${workspaceRoot}/node_modules/vitest/vitest.mjs",
			"console": "integratedTerminal",
			"args": ["--inspect=9229", "--no-file-parallelism"]
		},
		{
			"name": "Attach to Workers Runtime",
			"type": "node",
			"request": "attach",
			"port": 9229,
			"cwd": "/",
			"resolveSourceMapLocations": null,
			"attachExistingChildren": false,
			"autoAttachChildProcesses": false
		}
	],
	"compounds": [
		{
			"name": "Debug Workers tests",
			"configurations": [
				"Open inspector with Vitest",
				"Attach to Workers Runtime"
			],
			"stopAll": true
		}
	]
}

Select Debug Workers tests at the top of the Run & Debug panel to open an inspector with Vitest and attach a debugger to the Workers runtime. Then you can add breakpoints to your test files and start debugging.