More comments in the socket type definition (#19410)

Co-authored-by: Alistair Smith <hi@alistair.sh>

packages/bun-types/bun.d.ts

@@ -5871,31 +5871,76 @@ declare module "bun" {
     index: string;
   }
 
+  /**
+   * Represents a TCP or TLS socket connection used for network communication.
+   * This interface provides methods for reading, writing, managing the connection state,
+   * and handling TLS-specific features if applicable.
+   *
+   * Sockets are created using `Bun.connect()` or accepted by a `Bun.listen()` server.
+   *
+   * @category HTTP & Networking
+   */
   interface Socket<Data = undefined> extends Disposable {
     /**
-     * Write `data` to the socket
+     * Writes `data` to the socket. This method is unbuffered and non-blocking. This uses the `sendto(2)` syscall internally.
      *
-     * @param data The data to write to the socket
+     * For optimal performance with multiple small writes, consider batching multiple
-     * @param byteOffset The offset in the buffer to start writing from (defaults to 0)
+     * writes together into a single `socket.write()` call.
-     * @param byteLength The number of bytes to write (defaults to the length of the buffer)
      *
-     * When passed a string, `byteOffset` and `byteLength` refer to the UTF-8 offset, not the string character offset.
+     * @param data The data to write. Can be a string (encoded as UTF-8), `ArrayBuffer`, `TypedArray`, or `DataView`.
+     * @param byteOffset The offset in bytes within the buffer to start writing from. Defaults to 0. Ignored for strings.
+     * @param byteLength The number of bytes to write from the buffer. Defaults to the remaining length of the buffer from the offset. Ignored for strings.
+     * @returns The number of bytes written. Returns `-1` if the socket is closed or shutting down. Can return less than the input size if the socket's buffer is full (backpressure).
+     * @example
+     * ```ts
+     * // Send a string
+     * const bytesWritten = socket.write("Hello, world!\n");
      *
-     * This is unbuffered as of Bun v0.2.2. That means individual write() calls
+     * // Send binary data
-     * will be slow. In the future, Bun will buffer writes and flush them at the
+     * const buffer = new Uint8Array([0x01, 0x02, 0x03]);
-     * end of the tick, when the event loop is idle, or sooner if the buffer is full.
+     * socket.write(buffer);
+     *
+     * // Send part of a buffer
+     * const largeBuffer = new Uint8Array(1024);
+     * // ... fill largeBuffer ...
+     * socket.write(largeBuffer, 100, 50); // Write 50 bytes starting from index 100
+     * ```
      */
     write(data: string | BufferSource, byteOffset?: number, byteLength?: number): number;
 
     /**
-     * The data context for the socket.
+     * The user-defined data associated with this socket instance.
+     * This can be set when the socket is created via `Bun.connect({ data: ... })`.
+     * It can be read or updated at any time.
+     *
+     * @example
+     * ```ts
+     * // In a socket handler
+     * function open(socket: Socket<{ userId: string }>) {
+     *   console.log(`Socket opened for user: ${socket.data.userId}`);
+     *   socket.data.lastActivity = Date.now(); // Update data
+     * }
+     * ```
      */
     data: Data;
 
     /**
-     * Like {@link Socket.write} except it includes a TCP FIN packet
+     * Sends the final data chunk and initiates a graceful shutdown of the socket's write side.
+     * After calling `end()`, no more data can be written using `write()` or `end()`.
+     * The socket remains readable until the remote end also closes its write side or the connection is terminated.
+     * This sends a TCP FIN packet after writing the data.
      *
-     * Use it to send your last message and close the connection.
+     * @param data Optional final data to write before closing. Same types as `write()`.
+     * @param byteOffset Optional offset for buffer data.
+     * @param byteLength Optional length for buffer data.
+     * @returns The number of bytes written for the final chunk. Returns `-1` if the socket was already closed or shutting down.
+     * @example
+     * ```ts
+     * // send some data and close the write side
+     * socket.end("Goodbye!");
+     * // or close write side without sending final data
+     * socket.end();
+     * ```
      */
     end(data?: string | BufferSource, byteOffset?: number, byteLength?: number): number;
 
@@ -5922,20 +5967,33 @@ declare module "bun" {
     timeout(seconds: number): void;
 
     /**
-     * Forcefully close the socket. The other end may not receive all data, and
+     * Forcefully closes the socket connection immediately. This is an abrupt termination, unlike the graceful shutdown initiated by `end()`.
-     * the socket will be closed immediately.
+     * It uses `SO_LINGER` with `l_onoff=1` and `l_linger=0` before calling `close(2)`.
+     * Consider using {@link close close()} or {@link end end()} for graceful shutdowns.
      *
-     * This passes `SO_LINGER` with `l_onoff` set to `1` and `l_linger` set to
+     * @example
-     * `0` and then calls `close(2)`.
+     * ```ts
+     * socket.terminate();
+     * ```
      */
     terminate(): void;
 
     /**
-     * Shutdown writes to a socket
+     * Shuts down the write-half or both halves of the connection.
+     * This allows the socket to enter a half-closed state where it can still receive data
+     * but can no longer send data (`halfClose = true`), or close both read and write
+     * (`halfClose = false`, similar to `end()` but potentially more immediate depending on OS).
+     * Calls `shutdown(2)` syscall internally.
      *
-     * This makes the socket a half-closed socket. It can still receive data.
+     * @param halfClose If `true`, only shuts down the write side (allows receiving). If `false` or omitted, shuts down both read and write. Defaults to `false`.
+     * @example
+     * ```ts
+     * // Stop sending data, but allow receiving
+     * socket.shutdown(true);
      *
-     * This calls [shutdown(2)](https://man7.org/linux/man-pages/man2/shutdown.2.html) internally
+     * // Shutdown both reading and writing
+     * socket.shutdown();
+     * ```
      */
     shutdown(halfClose?: boolean): void;
 
@@ -5961,6 +6019,11 @@ declare module "bun" {
 
     /**
      * Flush any buffered data to the socket
+     * This attempts to send the data immediately, but success depends on the network conditions
+     * and the receiving end.
+     * It might be necessary after several `write` calls if immediate sending is critical,
+     * though often the OS handles flushing efficiently. Note that `write` calls outside
+     * `open`/`data`/`drain` might benefit from manual `cork`/`flush`.
      */
     flush(): void;
 
@@ -5982,17 +6045,31 @@ declare module "bun" {
 
     /**
      * Remote IP address connected to the socket
+     * @example "192.168.1.100" | "2001:db8::1"
      */
     readonly remoteAddress: string;
 
+    /**
+     * Remote port connected to the socket
+     * @example 8080
+     */
     readonly remotePort: number;
 
+    /**
+     * IP protocol family used for the local endpoint of the socket
+     * @example "IPv4" | "IPv6"
+     */
     readonly localFamily: "IPv4" | "IPv6";
 
+    /**
+     * Local IP address connected to the socket
+     * @example "192.168.1.100" | "2001:db8::1"
+     */
     readonly localAddress: string;
 
     /**
      * local port connected to the socket
+     * @example 8080
      */
     readonly localPort: number;
 
@@ -6156,6 +6233,8 @@ declare module "bun" {
     /**
      * See `Session Resumption` for more information.
      * @return `true` if the session was reused, `false` otherwise.
+     * **TLS Only:** Checks if the current TLS session was resumed from a previous session.
+     * Returns `true` if the session was resumed, `false` otherwise.
      */
     isSessionReused(): boolean;
 
@@ -6198,30 +6277,91 @@ declare module "bun" {
     setKeepAlive(enable?: boolean, initialDelay?: number): boolean;
 
     /**
-     * The number of bytes written to the socket.
+     * The total number of bytes successfully written to the socket since it was established.
+     * This includes data currently buffered by the OS but not yet acknowledged by the remote peer.
      */
     readonly bytesWritten: number;
 
+    /**
+     * Alias for `socket.end()`. Allows the socket to be used with `using` declarations
+     * for automatic resource management.
+     * @example
+     * ```ts
+     * async function processSocket() {
+     *   using socket = await Bun.connect({ ... });
+     *   socket.write("Data");
+     *   // socket.end() is called automatically when exiting the scope
+     * }
+     * ```
+     */
+    [Symbol.dispose](): void;
+
     resume(): void;
 
     pause(): void;
 
+    /**
+     * If this is a TLS Socket
+     */
     renegotiate(): void;
 
+    /**
+     * Sets the verify mode of the socket.
+     *
+     * @param requestCert Whether to request a certificate.
+     * @param rejectUnauthorized Whether to reject unauthorized certificates.
+     */
     setVerifyMode(requestCert: boolean, rejectUnauthorized: boolean): void;
 
     getSession(): void;
 
+    /**
+     * Sets the session of the socket.
+     *
+     * @param session The session to set.
+     */
     setSession(session: string | Buffer | BufferSource): void;
 
+    /**
+     * Exports the keying material of the socket.
+     *
+     * @param length The length of the keying material to export.
+     * @param label The label of the keying material to export.
+     * @param context The context of the keying material to export.
+     */
     exportKeyingMaterial(length: number, label: string, context?: string | BufferSource): void;
 
+    /**
+     * Upgrades the socket to a TLS socket.
+     *
+     * @param options The options for the upgrade.
+     * @returns A tuple containing the raw socket and the TLS socket.
+     * @see {@link TLSUpgradeOptions}
+     */
     upgradeTLS<Data>(options: TLSUpgradeOptions<Data>): [raw: Socket<Data>, tls: Socket<Data>];
 
+    /**
+     * Closes the socket.
+     *
+     * This is a wrapper around `end()` and `shutdown()`.
+     *
+     * @see {@link end}
+     * @see {@link shutdown}
+     */
     close(): void;
 
+    /**
+     * Returns the servername of the socket.
+     *
+     * @see {@link setServername}
+     */
     getServername(): string;
 
+    /**
+     * Sets the servername of the socket.
+     *
+     * @see {@link getServername}
+     */
     setServername(name: string): void;
   }
 

packages/bun-types/test.d.ts

@@ -88,18 +88,19 @@ declare module "bun:test" {
    */
   export function setSystemTime(now?: Date | number): ThisType<void>;
 
-  interface Jest {
-    restoreAllMocks(): void;
-    clearAllMocks(): void;
-    fn<T extends (...args: any[]) => any>(func?: T): Mock<T>;
-    setSystemTime(now?: number | Date): void;
-    setTimeout(milliseconds: number): void;
-    useFakeTimers(): void;
-    useRealTimers(): void;
-    spyOn: spyOn;
-  }
-  export const jest: Jest;
   export namespace jest {
+    function restoreAllMocks(): void;
+    function clearAllMocks(): void;
+    function fn<T extends (...args: any[]) => any>(func?: T): Mock<T>;
+    function setSystemTime(now?: number | Date): void;
+    function setTimeout(milliseconds: number): void;
+    function useFakeTimers(): void;
+    function useRealTimers(): void;
+    function spyOn<T extends object, K extends keyof T>(
+      obj: T,
+      methodOrPropertyValue: K,
+    ): Mock<Extract<T[K], (...args: any[]) => any>>;
+
     /**
      * Constructs the type of a mock function, e.g. the return type of `jest.fn()`.
      */

test/integration/bun-types/fixture/test.ts

@@ -1,4 +1,4 @@
-import { afterAll, afterEach, beforeAll, beforeEach, describe, expect, type Mock, spyOn, test } from "bun:test";
+import { afterAll, afterEach, beforeAll, beforeEach, describe, expect, jest, type Mock, spyOn, test } from "bun:test";
 import { expectType } from "./utilities";
 
 const hooks = [beforeAll, beforeEach, afterAll, afterEach];
@@ -141,3 +141,6 @@ expectType<Mock<(name: string) => string>>(myNormalSpiedMethod);
 
 const spy = spyOn(console, "log");
 expectType(spy.mock.calls).is<[message?: any, ...optionalParams: any[]][]>();
+
+jest.spyOn(console, "log");
+jest.fn(() => 123 as const);