How to Test Cursor-Generated Code: A Developer's Guide to Catching AI-Written Bugs Before They Ship

Cursor changed the default for how features get built. What has not changed is that untested code still breaks production — it just gets there faster.

What is the problem with testing Cursor-generated code?​

Cursor writes features. It does not write test suites.

That single gap is where production bugs now live. When an AI assistant generates a checkout flow, a dashboard widget, or a bug fix in twenty minutes, no one writes the corresponding Playwright or Cypress tests — because there is no time, and because writing tests for code you did not write feels backwards.

The result is a measurable shift in defect rates:

Speed without validation is just faster failure. To keep the velocity Cursor gives you, the testing layer has to move just as fast.

For a deeper take on why your coding agent is a poor substitute for a dedicated tester, see Why Your Coding Agent Can't Be Your Testing Agent. For the economic angle, see The Hidden Bill — Coding Agent vs Testing Agent.

How do you test code generated by Cursor?​

The direct answer: use an AI testing agent that reads your code changes, generates targeted E2E tests automatically, and runs them on real browsers — both inside the Cursor IDE and on every GitHub pull request.

The practical setup has two parts:

1. A Cursor IDE extension that runs git-aware tests from the sidebar while you code, so you catch bugs before you push.
2. A GitHub Action that auto-tests every PR, so nothing reaches main without validation.

DevAssure O2 powers both. You install the extension from Open VSX, add a single workflow file to .github/workflows/, and the agent handles change detection, test generation, browser execution, and reporting.

This lines up with the broader shift described in Vibe Testing — letting an agent own the test surface so humans stay on product work.

How DevAssure tests Cursor-generated code: step by step​

Here is what happens from prompt to merge:

1. Cursor generates the feature. You describe what you want — a checkout flow, a settings page, a bug fix — and Cursor writes the code.
2. You validate locally (optional). Open the DevAssure extension in Cursor's sidebar. It runs git-aware tests on your branch and surfaces issues before you commit.
3. You open a pull request. Standard GitHub workflow. Nothing changes.
4. O2 analyzes the diff. The GitHub Action inspects changed files, functions, and dependencies to map the blast radius of the change.
5. O2 generates and runs tests. Targeted E2E tests execute on real headless browsers in CI — typically within thirty minutes of opening the PR.
6. Results post to the PR. Failures arrive with screenshots and session replays. You fix and re-push, or merge with confidence.

For CI-native setup details, see DevAssure's O2 Agent on GitHub Marketplace.

What does the GitHub Action setup look like?​

One workflow file. That is the whole integration.

# .github/workflows/devassure.yml
name: DevAssure O2
on:
  pull_request:
    branches: [main]

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - uses: actions/setup-node@v4
        with:
          node-version: "24"
      - name: Run DevAssure
        uses: devassure-ai/devassure-action@v1
        env:
          DEVASSURE_TOKEN: ${{ secrets.DEVASSURE_TOKEN }}

Add the file, set the secret, and every PR against main gets auto-tested. The action works with code from Cursor, Copilot, Claude Code, Windsurf, Bolt, or a human keyboard — it tests diffs, not authors.

For more on Actions architecture, see GitHub Actions.

Cursor with DevAssure vs Cursor without DevAssure​

What kinds of bugs does this catch in AI-generated code?​

The bugs that matter most are the ones code review misses because they only show up at runtime:

• Null-reference failures — Cursor forgets a null check on a rarely-populated field.
• Broken validation logic — form rules pass unit tests but fail with real input.
• Checkout and payment regressions — multi-step flows that compile but do not complete.
• UI regressions — components that render but break on interaction.
• Cross-feature breakage — a refactor in one module silently breaks an unrelated flow.

Because O2 generates tests from the actual diff, coverage tracks the change. New code gets new tests; touched code gets regression checks.

Do I need to write any test scripts?​

No. This is the core design choice.

You do not write Playwright specs. You do not maintain Cypress page objects. O2 reads your code changes — either from the Cursor extension on a working branch or from a PR diff in CI — and generates the E2E tests it needs to validate the impact area.

For Cursor teams specifically, the typical results after adding O2 are:

If you are comparing approaches, many teams still pair agentic flows with traditional stacks — see Playwright + MCP for one lens on where scripted automation fits.

Does DevAssure work with AI coding tools other than Cursor?​

Yes. DevAssure tests code, not the tool that wrote it. The extension and GitHub Action both work with:

• Cursor
• GitHub Copilot
• Claude Code
• Windsurf
• Bolt
• VS Code
• Hand-written code

If it ends up as a diff in a pull request, O2 can analyze and test it.

How do I install the DevAssure Cursor extension?​

Install DevAssure Invisible (QA) Agent from the Open VSX registry — Cursor's extension marketplace is VS Code–compatible, and the extension is built for both editors.

1. Open the Extensions panel in Cursor.
2. Search for DevAssure, or install directly from the Open VSX listing.
3. Sign in with your DevAssure account (free tier available, no credit card).
4. Trigger git-aware test runs from the sidebar while you code.

For PR-level gating, add the DevAssure GitHub Action on top.

Frequently asked questions​

The bottom line​

Cursor changes how fast you can build. The bug-to-feature ratio changes with it. The teams shipping AI-generated code without slowing down are the ones who automated testing the same way they automated coding — agent in the IDE, agent on the PR, zero scripts in between.

Build with Cursor. Ship with DevAssure.

• Install the Cursor extension: Open VSX listing
• Add the GitHub Action: Marketplace listing
• Or sign up for the free tier: app.devassure.io/sign_up

Free tier. Two-minute setup. No credit card required.

Links​

• Vibe Testing: https://www.devassure.io/blog/vibe-testing/
• O2 PR testing agent: https://www.devassure.io/o2-testing-agent
• DevAssure O2 on GitHub Marketplace (blog): https://www.devassure.io/blog/devassure-o2-agent-github-marketplace/
• GitHub Actions guide: https://www.devassure.io/blog/github-actions/
• Why coding agents can't test: https://www.devassure.io/blog/why-coding-agents-cant-test/
• The quiet death of the test script: https://www.devassure.io/blog/quiet-death-of-the-test-script/
• DevAssure: https://www.devassure.io