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The browser runner executes your tests entirely inside your browser tab using WebContainers. There is no server involved, no infrastructure to configure, and no code uploaded to an external service.

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Supported frameworks

Jest

The default framework. Auto-detected when your test code uses expect() or jest imports.

Vitest

Auto-detected when your test code imports from vitest.

Mocha

Auto-detected when your test code uses mocha or chai.
You can also set the framework manually on the Execute page if auto-detection does not pick the right one.

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Running tests

1

Navigate to Execute

Click Execute in the sidebar navigation.
2

Add your test code

You have three options:
  • Paste code — click Paste Code and enter your test code directly.
  • Generate from analysis — run a codebase analysis and use the Execute Tests button on the results page. The generated test code is automatically loaded.
  • Try a sample — click Try Sample to load a pre-built example and see the runner in action.
3

Select tests

The Tests tab parses your code and lists the individual test cases. Select all or a subset to run.
4

Run

Click Run in the header. You are taken to the live execution view.

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Real-time output

While tests run, the execution view streams output in real time. The console panel on the right shows the raw terminal output from the test framework — pass and fail lines are color-coded green and red as they appear. When execution completes, the summary cards show:
MetricDescription
TotalTotal number of tests that ran
PassedTests that passed
FailedTests that failed
DurationTotal execution time
Pass ratePercentage of tests that passed
Individual test results are grouped by their describe() block. Click a failed test to see its error message and stack trace.

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Browser sandbox limitations

Because tests run inside a browser sandbox, there are constraints you should be aware of:
Tests that access the local file system will not work in the browser runner. The WebContainer environment does not have access to your machine’s file system.
  • No local file system access — fs operations that read from your host machine are not supported. Self-contained tests that define their own data work without issues.
  • Network calls go through the browser — outbound HTTP requests from your tests are subject to the browser’s CORS and security policies.
  • No native binaries — tests that spawn native processes or use native Node.js addons will not run.
For tests with these requirements, use the Strategy tab on the Execute page to configure an alternative execution approach.

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Environment configuration

Use the Environment tab to set custom environment variables that your tests can read at runtime. Variables are passed into the WebContainer before execution starts.
If your tests were generated by Orizon QA’s codebase analysis, they are written to be self-contained and work in the browser runner without additional configuration.