Add tests. Add exponential backoff contexts. Update error handling. Imrove Event Parser compatibility. Simplify SSE Session. Simplify Async Iterator.

tests/helpers/sse-stream.ts

@@ -0,0 +1,65 @@
+export type SseTestStreamOptions = {
+
+  /** Milliseconds to wait before enqueueing each chunk after the first. */
+  chunkDelayMs?: number;
+
+  /**
+   * When true, closes the body as soon as all initial chunks have been sent.
+   * Use this to simulate a server that sends events and then ends the stream.
+   */
+  closeWhenDone?: boolean;
+};
+
+/**
+* Test double for an SSE HTTP response body.
+*
+* Enqueues fixture chunks in order and stays open until {@link close} is called,
+* matching real servers that keep the connection alive after each event's trailing
+* `\n\n` frame boundary.
+*/
+export class SseTestStream {
+  readonly stream: ReadableStream<Uint8Array>;
+
+  private controller: ReadableStreamDefaultController<Uint8Array> | null = null;
+
+  private closed = false;
+
+  /**
+   * @param chunks - Fixture `raw` strings, whole or split, to simulate chunk boundaries.
+   * @param options - Delivery timing and optional auto-close after the initial chunks.
+   */
+  constructor(chunks: string[], options: SseTestStreamOptions = {}) {
+      const { chunkDelayMs = 0, closeWhenDone = false } = options;
+      const encoder = new TextEncoder();
+
+      this.stream = new ReadableStream({
+          start: async (controller): Promise<void> => {
+              this.controller = controller;
+
+              for (let i = 0; i < chunks.length; i++) {
+                  if (chunkDelayMs > 0 && i > 0) {
+                      await new Promise((resolve) => setTimeout(resolve, chunkDelayMs));
+                  }
+
+                  if (this.closed) return;
+
+                  controller.enqueue(encoder.encode(chunks[i]!));
+              }
+
+              if (closeWhenDone) {
+                  this.close();
+              }
+          },
+      });
+  }
+
+  /**
+   * Ends the HTTP body the way a server closing the SSE connection would.
+   */
+  close(): void {
+      if (this.closed) return;
+
+      this.closed = true;
+      this.controller?.close();
+  }
+}