Sub2API v1.0 - AI API 网关（二开初始版本，基于上游 Wei-Shaw/sub2api）

backend/internal/service/user_subscription_days_remaining_test.go

@@ -0,0 +1,37 @@
+//go:build unit
+
+package service
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestUserSubscriptionDaysRemainingAt(t *testing.T) {
+	now := time.Date(2026, time.July, 19, 12, 0, 0, 0, time.UTC)
+	tests := []struct {
+		name      string
+		expiresAt time.Time
+		want      int
+	}{
+		{name: "expired", expiresAt: now.Add(-time.Nanosecond), want: 0},
+		{name: "expires now", expiresAt: now, want: 0},
+		{name: "less than one day", expiresAt: now.Add(subscriptionDayDuration - time.Nanosecond), want: 1},
+		{name: "exactly one day", expiresAt: now.Add(subscriptionDayDuration), want: 1},
+		{name: "over one day", expiresAt: now.Add(subscriptionDayDuration + time.Nanosecond), want: 2},
+		{name: "less than two days", expiresAt: now.Add(2*subscriptionDayDuration - time.Nanosecond), want: 2},
+		{name: "exactly two days", expiresAt: now.Add(2 * subscriptionDayDuration), want: 2},
+		{name: "over two days", expiresAt: now.Add(2*subscriptionDayDuration + time.Nanosecond), want: 3},
+		{name: "exactly seven days", expiresAt: now.Add(7 * subscriptionDayDuration), want: 7},
+		{name: "over seven days", expiresAt: now.Add(7*subscriptionDayDuration + time.Nanosecond), want: 8},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			sub := &UserSubscription{ExpiresAt: tt.expiresAt}
+			require.Equal(t, tt.want, sub.daysRemainingAt(now))
+		})
+	}
+}