@bubblydoo/vitest-pool-cdp

Custom Vitest pool that runs tests inside CDP-connected runtimes (Chrome, Photoshop UXP, Electron, and similar environments).

Overview

@bubblydoo/vitest-pool-cdp runs Vitest tests in a remote JavaScript runtime by:

• opening a CDP connection from Node.js
• injecting a lightweight worker runtime into the target
• forwarding Vitest RPC traffic between Node and the target
• bundling test files with esbuild before evaluating them in the target

Supported by design:

• Vitest projects and allowOnly / testNamePattern propagation
• snapshot testing, including inline snapshots
• sourcemap-based error stack remapping (enabled by default)

Installation

pnpm add -D @bubblydoo/vitest-pool-cdp vitest
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Quick Start

// vitest.config.ts
import { defineConfig } from 'vitest/config';
import { cdpPool } from '@bubblydoo/vitest-pool-cdp';

export default defineConfig({
  test: {
    pool: cdpPool({
      cdp: 'ws://localhost:9222/devtools/page/ABC123',
    }),
  },
});
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Configuration

cdp (required)

cdp is the connection source. It supports:

• a static websocket URL (string)
• an async function returning a URL
• an async function returning { url, teardown }

cdp: async () => ({ url: await getUrl(), teardown: async () => stopTarget() })
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Select execution context or session

By default the pool enables auto-attach and runs in the attached target session. Use executionContextOrSession if you need to explicitly choose:

• { sessionId: string }
• { uniqueId: string } (execution context unique id)
• { id: number } (execution context id)

executionContextOrSession: async (cdp) => {
  const desc = await waitForExecutionContextCreated(cdp);
  return { uniqueId: desc.uniqueId };
}
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Options

Example (dynamic CDP + teardown)

import { defineConfig } from 'vitest/config';
import { cdpPool } from '@bubblydoo/vitest-pool-cdp';
import { setupDevtoolsUrl } from '@bubblydoo/uxp-devtools-common';

export default defineConfig({
  test: {
    pool: cdpPool({
      cdp: () => setupDevtoolsUrl('./plugin', 'com.example.plugin'),
      debug: true,
    }),
  },
});
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Runtime Model

┌──────────────────────────────┐                  ┌──────────────────────────────┐
│ Vitest process (Node.js)     │                  │ CDP target runtime           │
│                              │                  │ (Browser / UXP / Electron)   │
├──────────────────────────────┤                  ├──────────────────────────────┤
│ CdpPoolWorker                │                  │ Injected worker runtime      │
│                              │                  │                              │
│  ┌───────────────┐           │                  │  ┌───────────────┐           │
│  │ send()        │───────────┼─────────────────►│  │ receive()     │           │
│  └───────────────┘           │ Runtime.evaluate │  └───────────────┘           │
│                              │                  │                              │
│  ┌───────────────┐           │                  │  ┌───────────────┐           │
│  │ on('msg')     │◄──────────┼───────────────── │  │ post()        │           │
│  └───────────────┘           │ bindingCalled    │  └───────────────┘           │
└──────────────────────────────┘                  └──────────────────────────────┘
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send() -> receive() uses Runtime.evaluate. post() -> on('msg') uses Runtime.addBinding / Runtime.bindingCalled.

• Pool -> target messages are evaluated in the chosen CDP context/session.
• Target -> pool messages use Runtime.addBinding (not console transport), which avoids conflicts with extra debugger clients.
• Serialization uses devalue.

Snapshot Support

The worker runtime includes a Chai snapshot plugin built on @vitest/snapshot:

• toMatchSnapshot
• toMatchInlineSnapshot
• toThrowErrorMatchingSnapshot
• toThrowErrorMatchingInlineSnapshot
• expect.addSnapshotSerializer(...)

Local Chrome Test Viewer (package tests)

For packages/vitest-pool-cdp/test development, the Puppeteer launcher opens a local viewer page:

• test-viewer/index.html

When running:

pnpm --filter @bubblydoo/vitest-pool-cdp test:chrome
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the browser navigates to that page and shows live test results from __vitestUiUpdate / __vitestUiState (summary + per-test status, duration, and file path).

Current Limitations

• test.setupFiles is currently not implemented for this pool and throws an explicit error.
• Tests run in one remote runtime context/session at a time (no in-target worker isolation).
• Node-specific test behavior may not work in non-Node CDP targets.
• Target runtime should support modern JS (ES2022+).

License

MIT