make helper func more flexible

Author: JaredConover

Tests/OpenAITests/MockServerSentEvent.swift

@@ -21,15 +21,16 @@ struct MockServerSentEvent {
         "{\n    \"error\": {\n        \"message\": \"The model `o3-mini` does not exist or you do not have access to it.\",\n        \"type\": \"invalid_request_error\",\n        \"param\": null,\n        \"code\": \"model_not_found\"\n    }\n}\n".data(using: .utf8)!
     }
 
-    static func responseOutputTextDelta(
+    static func responseStreamEvent(
         itemId: String = "msg_1",
+        payloadType: String,
         outputIndex: Int = 0,
         contentIndex: Int = 0,
-        delta: String = "Hi",
+        delta: String = "",
         sequenceNumber: Int = 1
     ) -> Data {
         let json = """
-        {"type":"response.output_text.delta","output_index":\(outputIndex),"item_id":"\(itemId)","content_index":\(contentIndex),"delta":"\(delta)","sequence_number":\(sequenceNumber)}
+        {"type":"\(payloadType)","output_index":\(outputIndex),"item_id":"\(itemId)","content_index":\(contentIndex),"delta":"\(delta)","sequence_number":\(sequenceNumber)}
         """
         return "data: \(json)\n\n".data(using: .utf8)!
     }

Tests/OpenAITests/ModelResponseEventsStreamInterpreterTests.swift

@@ -56,8 +56,9 @@ final class ModelResponseEventsStreamInterpreterTests: XCTestCase {
         }
 
         interpreter.processData(
-            MockServerSentEvent.responseOutputTextDelta(
+            MockServerSentEvent.responseStreamEvent(
                 itemId: "msg_1",
+                payloadType: "response.output_text.delta",
                 outputIndex: 0,
                 contentIndex: 0,
                 delta: "Hi",