Running Unit Tests

Preferred: Use the runTests tool

If the runTests tool is available, prefer it over running shell commands. It provides structured output with detailed pass/fail information and supports filtering by file and test name.

• Pass absolute paths to test files via the files parameter.
• Pass test names via the testNames parameter to filter which tests run.
• Set mode="coverage" to collect coverage.

The tool runs tests discovered by VS Code's registered test controllers; it does not compile the repository or invoke a shell test command. If discovery is unavailable, pending, or reports no executed tests, treat the request as unvalidated and use the repository's configured test command. Review per-file and test-name diagnostics for partially matched requests instead of repeatedly checking the same paths.

Example (conceptual): run tests in src/vs/editor/test/common/model.test.ts with test name filter "should split lines".

Fallback: Shell scripts

When the runTests tool is not available (e.g. in CLI environments), use the platform-appropriate script from the repo root:

• macOS / Linux: ./scripts/test.sh [options]
• Windows: .\scripts\test.bat [options]

These scripts download Electron if needed and launch the Mocha test runner.

Commonly used options

Bare file paths - Run tests from specific files

Pass source file paths directly as positional arguments. The test runner automatically treats bare .ts/.js positional arguments as --run values.

./scripts/test.sh src/vs/editor/test/common/model.test.ts

.\scripts\test.bat src\vs\editor\test\common\model.test.ts

Multiple files:

./scripts/test.sh src/vs/editor/test/common/model.test.ts src/vs/editor/test/common/range.test.ts

--run <file> - Run tests from a specific file (explicit form)

Accepts a source file path (starting with src/). The runner strips the src/ prefix and the .ts/.js extension automatically to resolve the compiled module.

./scripts/test.sh --run src/vs/editor/test/common/model.test.ts

Multiple files can be specified by repeating --run:

./scripts/test.sh --run src/vs/editor/test/common/model.test.ts --run src/vs/editor/test/common/range.test.ts

--grep <pattern> (aliases: -g, -f) - Filter tests by name

Runs only tests whose full title matches the pattern (passed to Mocha's --grep).

./scripts/test.sh --grep "should split lines"

Combine with --run to filter tests within a specific file:

./scripts/test.sh --run src/vs/editor/test/common/model.test.ts --grep "should split lines"

--runGlob <pattern> (aliases: --glob, --runGrep) - Run tests matching a glob

Runs all test files matching a glob pattern against the compiled output directory. Useful for running all tests under a feature area.

./scripts/test.sh --runGlob "**/editor/test/**/*.test.js"

Note: the glob runs against compiled .js files in the output directory, not source .ts files.

--coverage - Generate a coverage report

./scripts/test.sh --run src/vs/editor/test/common/model.test.ts --coverage

--timeout <ms> - Set test timeout

Override the default Mocha timeout for long-running tests.

./scripts/test.sh --run src/vs/editor/test/common/model.test.ts --timeout 10000

--workers <count> - Run all test files in parallel processes

Spreads a run of all test files across <count> worker processes. The count is required, and capped at one worker per CPU and per 2 GB of memory, because every worker loads all test files. Every worker loads all test files and runs the files it claims, in the usual order. It is ignored, and the run uses a single window or process, with --run, --runList, --runGlob, bare file paths, --grep, --coverage or --dev. With --rerun-failed-files, the failures of all workers are rerun in a single window or process. When a worker fails, the runner prints the test files it ran, in order, to pass to --run to reproduce the failure. npm run test-node and npm run test-browser accept it as well; the browser runner starts its own browser in every worker, runs the browsers one at a time, and ignores it with --debug.

./scripts/test.sh --workers 4
npm run test-node -- --workers 4
npm run test-browser -- --browser chromium --workers 4

Integration tests

Integration tests (files ending in .integrationTest.ts or located in extensions/) are not run by scripts/test.sh. Use scripts/test-integration.sh (or scripts/test-integration.bat) instead. See the integration-tests skill for details.

Compilation requirement

Tests run against compiled JavaScript output. Reuse current output from an existing VS Code - Build task when available; otherwise refresh client output with npm run build-fast -- --client-only before running tests. This supports cold and incremental builds without a persistent watcher or extension builds. Use npm run build-fast when extension and Copilot outputs are also needed. Fast builds transpile rather than type-check, so run appropriate explicit type checks when warranted by the change. Do not rebuild between test selections when inputs have not changed. Test failures caused by stale output are a common pitfall.