diff --git a/AGENTS.md b/AGENTS.md new file mode 100644 index 0000000000..54277e966c --- /dev/null +++ b/AGENTS.md @@ -0,0 +1,113 @@ +# AGENTS.md + +This file provides guidance to AI coding agents (Claude Code, Codex, Copilot, Cursor, Aider, etc.) when working with code in this repository. + +## Project Overview + +This is the official MongoDB Node.js driver (`mongodb` npm package). It provides a TypeScript/JavaScript interface for applications to interact with MongoDB deployments. The driver implements the cross-driver MongoDB specifications. + +## Common Commands + +### Building + +```bash +npm run build:ts # Compile TypeScript to lib/ +npm run check:ts # Type-check without emitting +``` + +### Linting + +```bash +npm run check:eslint # Run ESLint +npm run fix:eslint # Auto-fix ESLint issues +``` + +### Testing + +Tests require a running MongoDB instance. To start one locally: + +```bash +git submodule update --init +export DRIVERS_TOOLS=$(pwd)/drivers-evergreen-tools +VERSION='latest' TOPOLOGY='replica_set' bash .evergreen/run-orchestration.sh +source mo-expansion.sh +``` + +```bash +npm run check:unit # Unit tests (no database required) +npm run check:test # Integration tests (requires database) +npm test # Lint + unit + integration + +# Run a single test by name pattern +npm run check:unit -- -g "pattern" +npm run check:test -- -g "pattern" +``` + +Tests use Mocha with 60-second timeout. Integration tests use a custom metadata UI that supports test filtering by topology, MongoDB version, auth, etc. via metadata: + +```js +describe( + 'my test', + { metadata: { requires: { topology: ['replicaset'], mongodb: '>=6.0' } } }, + function () {} +); +``` + +## Architecture + +### Layered Design + +``` +Public API (MongoClient, Db, Collection, Cursors) + → Operations (CRUD, Aggregation, Indexes, Bulk writes) + → Sessions & Transactions + → SDAM – Server Discovery And Monitoring (src/sdam/) + → CMAP – Connection Management And Pooling (src/cmap/) + → Wire Protocol & BSON serialization +``` + +### Key Source Directories + +- **`src/operations/`** — Each database command is an `AbstractOperation` subclass. Operations declare aspects (retryable, read/write, explainable) via Symbols. `execute_operation.ts` is the central execution engine handling retries, sessions, server selection. +- **`src/sdam/`** — Topology discovery and monitoring. `topology.ts` manages servers, `server_selection.ts` picks the best server based on read preference and latency, `monitor.ts` sends periodic heartbeats. +- **`src/cmap/`** — Connection pooling per server, wire protocol encoding/decoding, authentication handshakes. `auth/` contains implementations for each auth mechanism (SCRAM, X.509, AWS, OIDC, Kerberos, PLAIN). +- **`src/cursor/`** — `AbstractCursor` base with lazy evaluation, async iteration, and streaming. Specialized cursors: `FindCursor`, `AggregationCursor`, `ChangeStreamCursor`, etc. +- **`src/bulk/`** — Ordered and unordered bulk write operations. +- **`src/client-side-encryption/`** — Auto-encryption and explicit encryption (CSFLE/Queryable Encryption). +- **`src/gridfs/`** — GridFS file storage using upload/download streams. + +### How Operations Execute + +1. User calls a method (e.g., `collection.insertOne()`) +2. An operation object is created (e.g., `InsertOperation`) +3. `executeOperation()` handles: implicit session creation → server selection → connection checkout → command building → wire protocol send → response handling → retry on transient errors +4. Connection returned to pool, session cleaned up + +### Test Structure + +- **`test/unit/`** — Mirrors `src/` structure. No database interaction, uses mocks. +- **`test/integration/`** — Real database tests organized by feature area. +- **`test/spec/`** — YAML/JSON test specifications from the cross-driver specs. Implemented by spec runners in integration tests. Files named `*.spec.test.ts` use standardized runners; `*.prose.test.ts` are hand-written prose test implementations. +- **`test/mongodb.ts`** — Central re-export of all `src/` internals for test access. Tests import from `../../mongodb` (or appropriate depth), never directly from `src/`. + +## Code Conventions + +- **No `export default`** — All exports must be named. +- **No TypeScript enums** — Use string unions or `as const` objects instead. +- **No `node:` import prefix** — Use bare module names (e.g., `import { setTimeout } from 'timers'`). +- **Timer/process imports** — Must import `setTimeout`, `setInterval`, `clearTimeout`, `process`, etc. from their modules, not use globals. +- **No `Buffer`** — Use `Uint8Array` in source code. +- **BSON imports** — Source code must import from `src/bson.ts`, not from the `bson` package directly. +- **Null/undefined checks** — Use loose equality (`== null`) not strict (`=== null` or `=== undefined`). +- **Type imports** — Use `import { type Foo }` (inline type imports). +- **`return await`** — Required in `src/` (enforced by `@typescript-eslint/return-await: always`). +- **Error messages** — Sentence case, no trailing period. Use driver-specific error types extending `MongoError`. +- **Formatting** — Prettier with single quotes, 2-space tabs, 100-char width, no trailing commas. + +## Commit Messages + +Follow [Conventional Commits](https://www.conventionalcommits.org/): `(NODE-XXXX): ` + +Types: `feat`, `fix`, `docs`, `style`, `refactor`, `perf`, `test`, `chore` + +Breaking changes use `!`: `feat(NODE-XXXX)!: description`