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import type { ProviderEvent } from "@dispatch/kernel";
import { describe, expect, it } from "vitest";
import { parseSSELines } from "./parse-sse.js";
describe("parseSSELines", () => {
it("parses text delta events", () => {
const lines = [
'data: {"id":"chatcmpl-1","choices":[{"delta":{"content":"Hello"},"index":0}]}',
'data: {"id":"chatcmpl-1","choices":[{"delta":{"content":" world"},"index":0}]}',
'data: {"id":"chatcmpl-1","choices":[{"delta":{},"finish_reason":"stop","index":0}]}',
"data: [DONE]",
];
const events = parseSSELines(lines);
expect(events).toEqual([
{ type: "text-delta", delta: "Hello" },
{ type: "text-delta", delta: " world" },
{ type: "finish", reason: "stop" },
]);
});
it("parses a fragmented tool_call across chunks", () => {
const lines = [
'data: {"id":"chatcmpl-2","choices":[{"delta":{"tool_calls":[{"index":0,"id":"call_abc","function":{"name":"read_file","arguments":""}}]},"index":0}]}',
'data: {"id":"chatcmpl-2","choices":[{"delta":{"tool_calls":[{"index":0,"function":{"arguments":"{\\"path\\""}}]},"index":0}]}',
'data: {"id":"chatcmpl-2","choices":[{"delta":{"tool_calls":[{"index":0,"function":{"arguments":":\\"main.ts\\"}"}}]},"index":0}]}',
'data: {"id":"chatcmpl-2","choices":[{"delta":{},"finish_reason":"tool_calls","index":0}]}',
"data: [DONE]",
];
const events = parseSSELines(lines);
expect(events).toEqual([
{
type: "tool-call",
toolCallId: "call_abc",
toolName: "read_file",
input: { path: "main.ts" },
},
{ type: "finish", reason: "tool_calls" },
]);
});
it("parses multiple tool_calls in one response", () => {
const lines = [
'data: {"id":"chatcmpl-3","choices":[{"delta":{"tool_calls":[{"index":0,"id":"call_1","function":{"name":"read_file","arguments":""}}]},"index":0}]}',
'data: {"id":"chatcmpl-3","choices":[{"delta":{"tool_calls":[{"index":0,"function":{"arguments":"{\\"path\\":\\"a.ts\\"}"}}]},"index":0}]}',
'data: {"id":"chatcmpl-3","choices":[{"delta":{"tool_calls":[{"index":1,"id":"call_2","function":{"name":"read_file","arguments":""}}]},"index":0}]}',
'data: {"id":"chatcmpl-3","choices":[{"delta":{"tool_calls":[{"index":1,"function":{"arguments":"{\\"path\\":\\"b.ts\\"}"}}]},"index":0}]}',
'data: {"id":"chatcmpl-3","choices":[{"delta":{},"finish_reason":"tool_calls","index":0}]}',
"data: [DONE]",
];
const events = parseSSELines(lines);
expect(events).toEqual([
{ type: "tool-call", toolCallId: "call_1", toolName: "read_file", input: { path: "a.ts" } },
{ type: "tool-call", toolCallId: "call_2", toolName: "read_file", input: { path: "b.ts" } },
{ type: "finish", reason: "tool_calls" },
]);
});
it("parses usage from the final chunk", () => {
const lines = [
'data: {"id":"chatcmpl-4","choices":[{"delta":{"content":"Hi"},"index":0}]}',
'data: {"id":"chatcmpl-4","choices":[{"delta":{},"finish_reason":"stop","index":0}]}',
'data: {"id":"chatcmpl-4","usage":{"prompt_tokens":10,"completion_tokens":5}}',
"data: [DONE]",
];
const events = parseSSELines(lines);
expect(events).toEqual([
{ type: "text-delta", delta: "Hi" },
{ type: "finish", reason: "stop" },
{
type: "usage",
usage: {
inputTokens: 10,
outputTokens: 5,
cacheReadTokens: undefined,
cacheWriteTokens: undefined,
},
},
]);
});
it("parses reasoning_content deltas", () => {
const lines = [
'data: {"id":"chatcmpl-5","choices":[{"delta":{"reasoning_content":"Let me think..."},"index":0}]}',
'data: {"id":"chatcmpl-5","choices":[{"delta":{"content":"Here is my answer."},"index":0}]}',
'data: {"id":"chatcmpl-5","choices":[{"delta":{},"finish_reason":"stop","index":0}]}',
"data: [DONE]",
];
const events = parseSSELines(lines);
expect(events).toEqual([
{ type: "reasoning-delta", delta: "Let me think..." },
{ type: "text-delta", delta: "Here is my answer." },
{ type: "finish", reason: "stop" },
]);
});
it("handles invalid JSON gracefully", () => {
const lines = [
"data: {invalid json}",
'data: {"id":"chatcmpl-6","choices":[{"delta":{"content":"ok"},"index":0}]}',
"data: [DONE]",
];
const events = parseSSELines(lines);
expect(events).toHaveLength(2);
expect(events[0]?.type).toBe("error");
expect(events[1]).toEqual({ type: "text-delta", delta: "ok" });
});
it("ignores non-data lines", () => {
const lines = [
"event: message",
": comment line",
'data: {"id":"chatcmpl-7","choices":[{"delta":{"content":"hi"},"index":0}]}',
"",
"data: [DONE]",
];
const events = parseSSELines(lines);
expect(events).toEqual([{ type: "text-delta", delta: "hi" }]);
});
it("stops at [DONE] sentinel", () => {
const lines = [
'data: {"id":"chatcmpl-8","choices":[{"delta":{"content":"before"},"index":0}]}',
"data: [DONE]",
'data: {"id":"chatcmpl-8","choices":[{"delta":{"content":"after"},"index":0}]}',
];
const events = parseSSELines(lines);
expect(events).toEqual([{ type: "text-delta", delta: "before" }]);
});
it("parses nested prompt_tokens_details.cached_tokens → cacheReadTokens", () => {
const lines = [
'data: {"id":"chatcmpl-nested","choices":[{"delta":{},"finish_reason":"stop","index":0}]}',
'data: {"id":"chatcmpl-nested","usage":{"prompt_tokens":665,"completion_tokens":90,"prompt_tokens_details":{"cached_tokens":384},"completion_tokens_details":{"reasoning_tokens":86}}}',
"data: [DONE]",
];
const events = parseSSELines(lines);
const usageEvent = events.find((e) => e.type === "usage") as Extract<
ProviderEvent,
{ type: "usage" }
>;
expect(usageEvent.usage.inputTokens).toBe(665);
expect(usageEvent.usage.outputTokens).toBe(90);
expect(usageEvent.usage.cacheReadTokens).toBe(384);
expect(usageEvent.usage.cacheWriteTokens).toBeUndefined();
});
it("flat cache_read_tokens takes precedence over nested cached_tokens", () => {
const lines = [
'data: {"id":"chatcmpl-both","choices":[{"delta":{},"finish_reason":"stop","index":0}]}',
'data: {"id":"chatcmpl-both","usage":{"prompt_tokens":100,"completion_tokens":20,"cache_read_tokens":50,"prompt_tokens_details":{"cached_tokens":99}}}',
"data: [DONE]",
];
const events = parseSSELines(lines);
const usageEvent = events.find((e) => e.type === "usage") as Extract<
ProviderEvent,
{ type: "usage" }
>;
expect(usageEvent.usage.cacheReadTokens).toBe(50);
});
it("returns undefined for cacheReadTokens when neither flat nor nested present", () => {
const lines = [
'data: {"id":"chatcmpl-none","choices":[{"delta":{},"finish_reason":"stop","index":0}]}',
'data: {"id":"chatcmpl-none","usage":{"prompt_tokens":10,"completion_tokens":5}}',
"data: [DONE]",
];
const events = parseSSELines(lines);
const usageEvent = events.find((e) => e.type === "usage") as Extract<
ProviderEvent,
{ type: "usage" }
>;
expect(usageEvent.usage.cacheReadTokens).toBeUndefined();
expect(usageEvent.usage.cacheWriteTokens).toBeUndefined();
});
it("handles missing/partial prompt_tokens_details safely", () => {
const lines = [
'data: {"id":"chatcmpl-partial","choices":[{"delta":{},"finish_reason":"stop","index":0}]}',
'data: {"id":"chatcmpl-partial","usage":{"prompt_tokens":50,"completion_tokens":10,"prompt_tokens_details":{}}}',
"data: [DONE]",
];
const events = parseSSELines(lines);
const usageEvent = events.find((e) => e.type === "usage") as Extract<
ProviderEvent,
{ type: "usage" }
>;
expect(usageEvent.usage.cacheReadTokens).toBeUndefined();
});
it("handles empty prompt_tokens_details object safely", () => {
const lines = [
'data: {"id":"chatcmpl-empty","choices":[{"delta":{},"finish_reason":"stop","index":0}]}',
'data: {"id":"chatcmpl-empty","usage":{"prompt_tokens":30,"completion_tokens":8,"prompt_tokens_details":null}}',
"data: [DONE]",
];
const events = parseSSELines(lines);
const usageEvent = events.find((e) => e.type === "usage") as Extract<
ProviderEvent,
{ type: "usage" }
>;
expect(usageEvent.usage.cacheReadTokens).toBeUndefined();
});
it("handles a complete turn with text, tool call, usage, and finish", () => {
const lines = [
'data: {"id":"chatcmpl-9","choices":[{"delta":{"content":"Let me check."},"index":0}]}',
'data: {"id":"chatcmpl-9","choices":[{"delta":{"tool_calls":[{"index":0,"id":"call_xyz","function":{"name":"search","arguments":""}}]},"index":0}]}',
'data: {"id":"chatcmpl-9","choices":[{"delta":{"tool_calls":[{"index":0,"function":{"arguments":"{\\"query\\":"}}]},"index":0}]}',
'data: {"id":"chatcmpl-9","choices":[{"delta":{"tool_calls":[{"index":0,"function":{"arguments":"\\"dispatch\\"}"}}]},"index":0}]}',
'data: {"id":"chatcmpl-9","choices":[{"delta":{},"finish_reason":"tool_calls","index":0}]}',
'data: {"id":"chatcmpl-9","usage":{"prompt_tokens":50,"completion_tokens":20}}',
"data: [DONE]",
];
const events = parseSSELines(lines);
expect(events).toEqual([
{ type: "text-delta", delta: "Let me check." },
{
type: "tool-call",
toolCallId: "call_xyz",
toolName: "search",
input: { query: "dispatch" },
},
{ type: "finish", reason: "tool_calls" },
{
type: "usage",
usage: {
inputTokens: 50,
outputTokens: 20,
cacheReadTokens: undefined,
cacheWriteTokens: undefined,
},
},
]);
});
it("handles tool_call with unparseable arguments as raw string", () => {
const lines = [
'data: {"id":"chatcmpl-10","choices":[{"delta":{"tool_calls":[{"index":0,"id":"call_bad","function":{"name":"foo","arguments":"not-json"}}]},"index":0}]}',
'data: {"id":"chatcmpl-10","choices":[{"delta":{},"finish_reason":"tool_calls","index":0}]}',
"data: [DONE]",
];
const events = parseSSELines(lines);
expect(events).toEqual([
{ type: "tool-call", toolCallId: "call_bad", toolName: "foo", input: "not-json" },
{ type: "finish", reason: "tool_calls" },
]);
});
});
|
