feat: add streaming tests for streamText function

This commit introduces a new test suite for the streamText function, verifying that it correctly emits a stream_done event when the stream ends. Additionally, a utility function, iterableFromArray, is added to facilitate the creation of async iterables for testing purposes.

Author: nickytonline

src/lib/streaming.test.ts

@@ -1,5 +1,20 @@
 import { describe, it, expect } from 'vitest'
 import { stopStreamProcessing } from './utils/streaming'
+import { streamText } from './streaming'
+
+function iterableFromArray<T>(arr: T[]): AsyncIterable<T> {
+  return {
+    [Symbol.asyncIterator]() {
+      let i = 0
+      return {
+        next: async () =>
+          i < arr.length
+            ? { value: arr[i++], done: false }
+            : { value: undefined, done: true },
+      }
+    },
+  }
+}
 
 describe('stopStreamProcessing', () => {
   it('replaces response body with an empty closed stream', async () => {
@@ -59,3 +74,73 @@ describe('stopStreamProcessing', () => {
     expect(response.body).toBeInstanceOf(ReadableStream)
   })
 })
+
+describe('streamText', () => {
+  it('emits stream_done when the stream ends', async () => {
+    // Simulate a normal completion (not timing out)
+    const chunks = [
+      { type: 'response.output_text.delta', delta: "I'm glad you asked!" },
+      {
+        type: 'response.output_text.delta',
+        delta: ' Here are a few universally nice things that',
+      },
+      {
+        type: 'response.output_text.delta',
+        delta: ' could have happened today:\n\n',
+      },
+      {
+        type: 'response.output_text.delta',
+        delta: '- Someone smiled at a stranger, brightening',
+      },
+      { type: 'response.output_text.delta', delta: ' their day\n' },
+      {
+        type: 'response.output_text.delta',
+        delta: '- A teacher helped a student understand a',
+      },
+      { type: 'response.output_text.delta', delta: ' difficult concept\n' },
+      {
+        type: 'response.output_text.delta',
+        delta: '- A kind person paid for someone’s coffee',
+      },
+      { type: 'response.output_text.delta', delta: ' in line\n' },
+      {
+        type: 'response.output_text.delta',
+        delta: '- A pet reunited with its owner at a local',
+      },
+      { type: 'response.output_text.delta', delta: ' animal shelter\n' },
+      {
+        type: 'response.output_text.delta',
+        delta: '- A friend reached out just to say hello\n\n',
+      },
+      {
+        type: 'response.output_text.delta',
+        delta: 'Would you like to hear some real, uplifting',
+      },
+      { type: 'response.output_text.delta', delta: ' news from today?' },
+      { type: 'response.output_text.delta', delta: ' Just let me know!' },
+      {
+        type: 'response.tool_call_completed',
+        response: {
+          /* ...omitted... */
+        },
+      },
+      {
+        type: 'response.completed',
+        response: {
+          /* ...omitted... */
+        },
+      },
+    ]
+    const response = streamText(iterableFromArray(chunks))
+    const reader = response.body!.getReader()
+    let result = ''
+    let done = false
+    while (!done) {
+      const { value, done: d } = await reader.read()
+      if (value) result += new TextDecoder().decode(value)
+      done = d
+    }
+    // Should include t:{...stream_done...}
+    expect(result).toMatch(/t:{\"type\":\"stream_done\"}/)
+  })
+})