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sub2api/backend/internal/handler/gateway_handler_stream_failover_test.go
2026-03-15 16:21:49 +08:00

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package handler
import (
"net/http"
"net/http/httptest"
"strings"
"testing"
"github.com/Wei-Shaw/sub2api/internal/service"
"github.com/gin-gonic/gin"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
// partialMessageStartSSE 模拟 handleStreamingResponse 已写入的首批 SSE 事件。
const partialMessageStartSSE = "event: message_start\ndata: {\"type\":\"message_start\",\"message\":{\"id\":\"msg_01\",\"type\":\"message\",\"role\":\"assistant\",\"content\":[],\"model\":\"claude-sonnet-4-5\",\"stop_reason\":null,\"stop_sequence\":null,\"usage\":{\"input_tokens\":10,\"output_tokens\":1}}}\n\n" +
"event: content_block_start\ndata: {\"type\":\"content_block_start\",\"index\":0,\"content_block\":{\"type\":\"text\",\"text\":\"\"}}\n\n"
// TestStreamWrittenGuard_MessagesPath_AbortFailoverOnSSEContentWritten 验证:
// 当 Forward 在返回 UpstreamFailoverError 前已向客户端写入 SSE 内容时,
// 故障转移保护逻辑必须终止循环并发送 SSE 错误事件,而不是进行下一次 Forward。
// 具体验证:
// 1. c.Writer.Size() 检测条件正确触发(字节数已增加)
// 2. handleFailoverExhausted 以 streamStarted=true 调用后,响应体以 SSE 错误事件结尾
// 3. 响应体中只出现一个 message_start不存在第二个防止流拼接腐化
func TestStreamWrittenGuard_MessagesPath_AbortFailoverOnSSEContentWritten(t *testing.T) {
gin.SetMode(gin.TestMode)
w := httptest.NewRecorder()
c, _ := gin.CreateTestContext(w)
c.Request = httptest.NewRequest(http.MethodPost, "/v1/messages", nil)
// 步骤 1记录 Forward 前的 writer size模拟 writerSizeBeforeForward := c.Writer.Size()
sizeBeforeForward := c.Writer.Size()
require.Equal(t, -1, sizeBeforeForward, "gin writer 初始 Size 应为 -1未写入任何字节")
// 步骤 2模拟 Forward 已向客户端写入部分 SSE 内容message_start + content_block_start
_, err := c.Writer.Write([]byte(partialMessageStartSSE))
require.NoError(t, err)
// 步骤 3验证守卫条件成立c.Writer.Size() != sizeBeforeForward
require.NotEqual(t, sizeBeforeForward, c.Writer.Size(),
"写入 SSE 内容后 writer size 必须增加,守卫条件应为 true")
// 步骤 4模拟 UpstreamFailoverError上游在流中途返回 403
failoverErr := &service.UpstreamFailoverError{
StatusCode: http.StatusForbidden,
ResponseBody: []byte(`{"error":{"type":"permission_error","message":"forbidden"}}`),
}
// 步骤 5守卫触发 → 调用 handleFailoverExhaustedstreamStarted=true
h := &GatewayHandler{}
h.handleFailoverExhausted(c, failoverErr, service.PlatformAnthropic, true)
body := w.Body.String()
// 断言 A响应体中包含最初写入的 message_start SSE 事件行
require.Contains(t, body, "event: message_start", "响应体应包含已写入的 message_start SSE 事件")
// 断言 B响应体以 SSE 错误事件结尾data: {"type":"error",...}\n\n
require.True(t, strings.HasSuffix(strings.TrimRight(body, "\n"), "}"),
"响应体应以 JSON 对象结尾SSE error event 的 data 字段)")
require.Contains(t, body, `"type":"error"`, "响应体末尾必须包含 SSE 错误事件")
// 断言 CSSE event 行 "event: message_start" 只出现一次(防止双 message_start 拼接腐化)
firstIdx := strings.Index(body, "event: message_start")
lastIdx := strings.LastIndex(body, "event: message_start")
assert.Equal(t, firstIdx, lastIdx,
"响应体中 'event: message_start' 必须只出现一次,不得因 failover 拼接导致两次")
}
// TestStreamWrittenGuard_GeminiPath_AbortFailoverOnSSEContentWritten 与上述测试相同,
// 验证 Gemini 路径使用 service.PlatformGemini而非 account.Platform时行为一致。
func TestStreamWrittenGuard_GeminiPath_AbortFailoverOnSSEContentWritten(t *testing.T) {
gin.SetMode(gin.TestMode)
w := httptest.NewRecorder()
c, _ := gin.CreateTestContext(w)
c.Request = httptest.NewRequest(http.MethodPost, "/v1beta/models/gemini-2.0-flash:streamGenerateContent", nil)
sizeBeforeForward := c.Writer.Size()
_, err := c.Writer.Write([]byte(partialMessageStartSSE))
require.NoError(t, err)
require.NotEqual(t, sizeBeforeForward, c.Writer.Size())
failoverErr := &service.UpstreamFailoverError{
StatusCode: http.StatusForbidden,
}
h := &GatewayHandler{}
h.handleFailoverExhausted(c, failoverErr, service.PlatformGemini, true)
body := w.Body.String()
require.Contains(t, body, "event: message_start")
require.Contains(t, body, `"type":"error"`)
firstIdx := strings.Index(body, "event: message_start")
lastIdx := strings.LastIndex(body, "event: message_start")
assert.Equal(t, firstIdx, lastIdx, "Gemini 路径不得出现双 message_start")
}
// TestStreamWrittenGuard_NoByteWritten_GuardNotTriggered 验证反向场景:
// 当 Forward 返回 UpstreamFailoverError 时若未向客户端写入任何 SSE 内容,
// 守卫条件c.Writer.Size() != sizeBeforeForward为 false不应中止 failover。
func TestStreamWrittenGuard_NoByteWritten_GuardNotTriggered(t *testing.T) {
gin.SetMode(gin.TestMode)
w := httptest.NewRecorder()
c, _ := gin.CreateTestContext(w)
c.Request = httptest.NewRequest(http.MethodPost, "/v1/messages", nil)
// 模拟 writerSizeBeforeForward初始为 -1
sizeBeforeForward := c.Writer.Size()
// Forward 未写入任何字节直接返回错误(例如 401 发生在连接建立前)
// c.Writer.Size() 仍为 -1
// 守卫条件sizeBeforeForward == c.Writer.Size() → 不触发
guardTriggered := c.Writer.Size() != sizeBeforeForward
require.False(t, guardTriggered,
"未写入任何字节时,守卫条件必须为 false应允许正常 failover 继续")
}