Share upstream event stream hub

2026-04-24 12:30:11 +03:00
parent 8e610ca8b3
commit 7030549d78
12 changed files with 1436 additions and 201 deletions
@@ -0,0 +1,159 @@
+import { describe, expect, it } from 'vitest';
+
+import { createUpstreamSseReader } from './upstream-reader.js';
+
+function createSseResponse({ blocks = [], signal, holdOpen = false }) {
+  const encoder = new TextEncoder();
+  let index = 0;
+
+  return {
+    ok: true,
+    status: 200,
+    body: {
+      getReader() {
+        return {
+          async read() {
+            if (index < blocks.length) {
+              return { value: encoder.encode(blocks[index++]), done: false };
+            }
+
+            if (!holdOpen) {
+              return { value: undefined, done: true };
+            }
+
+            return new Promise((_resolve, reject) => {
+              const onAbort = () => {
+                signal.removeEventListener('abort', onAbort);
+                const error = new Error('Aborted');
+                error.name = 'AbortError';
+                reject(error);
+              };
+              signal.addEventListener('abort', onAbort, { once: true });
+            });
+          },
+        };
+      },
+    },
+  };
+}
+
+describe('createUpstreamSseReader', () => {
+  it('emits parsed events and tracks the latest event id', async () => {
+    const events = [];
+    let reader;
+
+    reader = createUpstreamSseReader({
+      buildUrl: () => 'http://127.0.0.1:4096/global/event',
+      reconnectDelayMs: 0,
+      fetchImpl: async (_url, options) => createSseResponse({
+        signal: options.signal,
+        blocks: [
+          'id: evt-1\r\ndata: {"type":"server.connected","properties":{"directory":"/tmp/project"}}\r\n\r\n',
+        ],
+      }),
+      onEvent(event) {
+        events.push(event);
+        reader.stop();
+      },
+    });
+
+    await reader.start();
+
+    expect(events).toHaveLength(1);
+    expect(events[0].eventId).toBe('evt-1');
+    expect(events[0].directory).toBe('/tmp/project');
+    expect(events[0].payload).toEqual({
+      type: 'server.connected',
+      properties: {
+        directory: '/tmp/project',
+      },
+    });
+    expect(reader.getLastEventId()).toBe('evt-1');
+  });
+
+  it('reconnects a stalled stream with Last-Event-ID', async () => {
+    const fetchLastEventIds = [];
+    const events = [];
+    let attempt = 0;
+    let reader;
+
+    reader = createUpstreamSseReader({
+      buildUrl: () => 'http://127.0.0.1:4096/global/event',
+      stallTimeoutMs: 10,
+      reconnectDelayMs: 0,
+      fetchImpl: async (_url, options) => {
+        fetchLastEventIds.push(options.headers['Last-Event-ID'] ?? null);
+        attempt += 1;
+
+        if (attempt === 1) {
+          return createSseResponse({
+            signal: options.signal,
+            holdOpen: true,
+            blocks: [
+              'id: evt-1\ndata: {"type":"server.connected","properties":{}}\n\n',
+            ],
+          });
+        }
+
+        return createSseResponse({
+          signal: options.signal,
+          blocks: [
+            'id: evt-2\ndata: {"type":"session.updated","properties":{}}\n\n',
+          ],
+        });
+      },
+      onEvent(event) {
+        events.push(event.eventId);
+        if (event.eventId === 'evt-2') {
+          reader.stop();
+        }
+      },
+    });
+
+    await reader.start();
+
+    expect(events).toEqual(['evt-1', 'evt-2']);
+    expect(fetchLastEventIds.slice(0, 2)).toEqual([null, 'evt-1']);
+    expect(reader.getLastEventId()).toBe('evt-2');
+  });
+
+  it('reports unavailable upstream responses and continues reconnecting until stopped', async () => {
+    const errors = [];
+    let attempt = 0;
+    let reader;
+
+    reader = createUpstreamSseReader({
+      buildUrl: () => 'http://127.0.0.1:4096/global/event',
+      reconnectDelayMs: 0,
+      fetchImpl: async (_url, options) => {
+        attempt += 1;
+        if (attempt === 1) {
+          return { ok: false, status: 503, body: null };
+        }
+
+        return createSseResponse({
+          signal: options.signal,
+          blocks: [
+            'id: evt-1\ndata: {"type":"server.connected","properties":{}}\n\n',
+          ],
+        });
+      },
+      onError(error) {
+        errors.push(error);
+      },
+      onEvent() {
+        reader.stop();
+      },
+    });
+
+    await reader.start();
+
+    expect(errors).toEqual([
+      expect.objectContaining({
+        type: 'upstream_unavailable',
+        status: 503,
+      }),
+    ]);
+    expect(attempt).toBe(2);
+  });
+});