Visual Studio Code is a code editor that supports editing, navigating, understanding, debugging, and extending software projects. Developers use it for the edit-build-debug cycle, and the catalogue add-ons provide skills, instructions, and agents for working within the editor.
Borrowing it
Nothing to install: this file belongs to microsoft/vscode. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/microsoft/vscode/main/.github/instructions/writing-tests.instructions.mdgit clone --depth 1 https://github.com/microsoft/vscodeWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/microsoft/vscode/writing-tests)<a href="https://agentmods.dev/instructions/microsoft/vscode/writing-tests"><img src="https://agentmods.dev/badge/instructions/microsoft/vscode/writing-tests/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/instructions/microsoft/vscode/writing-tests"><img src="https://agentmods.dev/badge/instructions/microsoft/vscode/writing-tests.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00558 | $0.00558 |
| Opus 5.5 | $0.00223 | $0.00223 |
| Sonnet 5.5 | $0.00112 | $0.00112 |
| Haiku 4.5 | $0.00056 | $0.00056 |
Grade A, and why
vscode writing-tests.instructions.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 57 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Writing Tests
Canonical reference: https://github.com/microsoft/vscode/wiki/Writing-Tests
Test Types
| Type | File suffix | Location | Runs in |
|---|---|---|---|
| Unit tests | .test.ts |
src/vs/**/test/ |
Browser, Electron, or Node.js (depends on layer) |
| Integration tests | .integrationTest.ts |
src/vs/**/test/ |
Real external APIs |
| Extension tests | Standard extension test system | extensions/*/ |
Extension host |
Running Tests
- Unit tests:
scripts/test.sh(macOS/Linux) orscripts/test.bat(Windows)- Filter:
--grep <pattern> - Glob:
--runGlob **/myFile.test.js
- Filter:
- Integration tests:
scripts/test-integration.shorscripts/test-integration.bat - VS Code UI: Use the Selfhost Test Provider
Writing Unit Tests
Tests use Mocha's BDD interface (suite/test) with the assert module and sinon for mocks.
Clean Teardown
Always use ensureNoDisposablesAreLeakedInTestSuite() to catch disposal leaks:
suite('myTests', () => {
const store = ensureNoDisposablesAreLeakedInTestSuite();
test('example', () => {
const disposable = store.add(new MyDisposable());
// ...
});
});
Always call sinon.restore() in teardown to avoid leaking mocks.
Best Practices
- Minimize assertions per test — prefer one
assert.deepStrictEqualsnapshot over many fine-grained assertions - Don't add tests to the wrong suite — find the relevant
suiteblock - Follow existing patterns (
describe/testorsuite/test) consistently within a file - Don't stub globals (e.g.,
(mainWindow as any).X = ...) — make dependencies injectable instead
Snapshot Testing
Use assertSnapshot for Jest-like snapshot tests. Snapshots are written to a __snapshots__ directory beside the test file on first run — verify the output is correct, then subsequent runs compare against it.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 57 lines · 558 tokens per session scan A 7e5748d8fe12
vscode writing-tests.instructions.md is an instructions file published in the GitHub repository microsoft/vscode (193,657 stars, last pushed today), licensed MIT. It adds 558 tokens to every session, about $0.0022 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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