internal/server/upstream_timeout_test.go

// upstream_timeout_test.go 钉住 isUpstreamTimeout 的三态判定口径：超时和
// "网络抖动"此前共用同一条换号路径——注定超时的请求会轮转 MaxRotate 次，
// 期间还给一串健康号喂连败计数。移植自 OkRoromori 分支（七例对照）。
package server

import (
	"context"
	"errors"
	"fmt"
	"net"
	"testing"
)

type timeoutErr struct{ timeout bool }

func (e timeoutErr) Error() string   { return "stub" }
func (e timeoutErr) Timeout() bool   { return e.timeout }
func (e timeoutErr) Temporary() bool { return e.timeout }

func TestIsUpstreamTimeout(t *testing.T) {
	cases := []struct {
		name       string
		err        error
		clientGone bool
		want       bool
	}{
		{"net.Error 超时", timeoutErr{true}, false, true},
		{"net.Error 非超时（连接被拒）", timeoutErr{false}, false, false},
		{"显式 deadline", fmt.Errorf("read: %w", context.DeadlineExceeded), false, true},
		{"客户端断连（ctx 已取消）", context.Canceled, true, false},
		{"空闲看门狗掐流（客户端仍在）", context.Canceled, false, true},
		{"普通错误", errors.New("boom"), false, false},
		{"nil", nil, false, false},
	}
	for _, c := range cases {
		t.Run(c.name, func(t *testing.T) {
			if got := isUpstreamTimeout(c.err, c.clientGone); got != c.want {
				t.Fatalf("isUpstreamTimeout(%v, clientGone=%v) = %v, want %v", c.err, c.clientGone, got, c.want)
			}
		})
	}

	// 保证 stub 真的实现了 net.Error（否则上面的用例会静默走不到 Timeout 分支）
	var ne net.Error = timeoutErr{true}
	_ = ne
}