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

backend/internal/service/billing_service_image_test.go

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+//go:build unit
+
+package service
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+// TestCalculateImageCost_DefaultPricing 测试无分组配置时使用默认价格
+func TestCalculateImageCost_DefaultPricing(t *testing.T) {
+	svc := &BillingService{} // pricingService 为 nil，使用硬编码默认值
+
+	// 2K 尺寸，默认价格 $0.134 * 1.5 = $0.201
+	cost := svc.CalculateImageCost("gemini-3-pro-image", "2K", 1, nil, 1.0)
+	require.InDelta(t, 0.201, cost.TotalCost, 0.0001)
+	require.InDelta(t, 0.201, cost.ActualCost, 0.0001)
+
+	// 多张图片
+	cost = svc.CalculateImageCost("gemini-3-pro-image", "2K", 3, nil, 1.0)
+	require.InDelta(t, 0.603, cost.TotalCost, 0.0001)
+}
+
+// TestCalculateImageCost_GroupCustomPricing 测试分组自定义价格
+func TestCalculateImageCost_GroupCustomPricing(t *testing.T) {
+	svc := &BillingService{}
+
+	price1K := 0.10
+	price2K := 0.15
+	price4K := 0.30
+	groupConfig := &ImagePriceConfig{
+		Price1K: &price1K,
+		Price2K: &price2K,
+		Price4K: &price4K,
+	}
+
+	// 1K 使用分组价格
+	cost := svc.CalculateImageCost("gemini-3-pro-image", "1K", 2, groupConfig, 1.0)
+	require.InDelta(t, 0.20, cost.TotalCost, 0.0001)
+
+	// 2K 使用分组价格
+	cost = svc.CalculateImageCost("gemini-3-pro-image", "2K", 1, groupConfig, 1.0)
+	require.InDelta(t, 0.15, cost.TotalCost, 0.0001)
+
+	// 4K 使用分组价格
+	cost = svc.CalculateImageCost("gemini-3-pro-image", "4K", 1, groupConfig, 1.0)
+	require.InDelta(t, 0.30, cost.TotalCost, 0.0001)
+}
+
+func TestCalculateImageCost_NormalizesInvalidSizeTo2K(t *testing.T) {
+	svc := &BillingService{}
+
+	price2K := 0.25
+	groupConfig := &ImagePriceConfig{Price2K: &price2K}
+
+	for _, imageSize := range []string{"", "auto", "not-a-size"} {
+		t.Run(imageSize, func(t *testing.T) {
+			cost := svc.CalculateImageCost("gemini-3-pro-image", imageSize, 2, groupConfig, 1.0)
+			require.InDelta(t, 0.50, cost.TotalCost, 0.0001)
+			require.InDelta(t, 0.50, cost.ActualCost, 0.0001)
+		})
+	}
+}
+
+// TestCalculateImageCost_4KDoublePrice 测试 4K 默认价格翻倍
+func TestCalculateImageCost_4KDoublePrice(t *testing.T) {
+	svc := &BillingService{}
+
+	// 4K 尺寸，默认价格翻倍 $0.134 * 2 = $0.268
+	cost := svc.CalculateImageCost("gemini-3-pro-image", "4K", 1, nil, 1.0)
+	require.InDelta(t, 0.268, cost.TotalCost, 0.0001)
+}
+
+// TestCalculateImageCost_RateMultiplier 测试费率倍数
+func TestCalculateImageCost_RateMultiplier(t *testing.T) {
+	svc := &BillingService{}
+
+	// 费率倍数 1.5x
+	cost := svc.CalculateImageCost("gemini-3-pro-image", "2K", 1, nil, 1.5)
+	require.InDelta(t, 0.201, cost.TotalCost, 0.0001)   // TotalCost = 0.134 * 1.5
+	require.InDelta(t, 0.3015, cost.ActualCost, 0.0001) // ActualCost = 0.201 * 1.5
+
+	// 费率倍数 2.0x
+	cost = svc.CalculateImageCost("gemini-3-pro-image", "2K", 2, nil, 2.0)
+	require.InDelta(t, 0.402, cost.TotalCost, 0.0001)
+	require.InDelta(t, 0.804, cost.ActualCost, 0.0001)
+}
+
+// TestCalculateImageCost_ZeroCount 测试 imageCount=0
+func TestCalculateImageCost_ZeroCount(t *testing.T) {
+	svc := &BillingService{}
+
+	cost := svc.CalculateImageCost("gemini-3-pro-image", "2K", 0, nil, 1.0)
+	require.Equal(t, 0.0, cost.TotalCost)
+	require.Equal(t, 0.0, cost.ActualCost)
+}
+
+// TestCalculateImageCost_NegativeCount 测试 imageCount=-1
+func TestCalculateImageCost_NegativeCount(t *testing.T) {
+	svc := &BillingService{}
+
+	cost := svc.CalculateImageCost("gemini-3-pro-image", "2K", -1, nil, 1.0)
+	require.Equal(t, 0.0, cost.TotalCost)
+	require.Equal(t, 0.0, cost.ActualCost)
+}
+
+// TestCalculateImageCost_ZeroRateMultiplier 锁定新行为：倍率 0 直接按 0 计费
+// （保存时已强制 > 0；若仍有 0 泄漏到计费层，零消耗比历史的 1.0 更安全）。
+func TestCalculateImageCost_ZeroRateMultiplier(t *testing.T) {
+	svc := &BillingService{}
+
+	cost := svc.CalculateImageCost("gemini-3-pro-image", "2K", 1, nil, 0)
+	require.InDelta(t, 0.201, cost.TotalCost, 0.0001)
+	require.InDelta(t, 0.0, cost.ActualCost, 1e-10)
+}
+
+// TestGetImageUnitPrice_GroupPriorityOverDefault 测试分组价格优先于默认价格
+func TestGetImageUnitPrice_GroupPriorityOverDefault(t *testing.T) {
+	svc := &BillingService{}
+
+	price2K := 0.20
+	groupConfig := &ImagePriceConfig{
+		Price2K: &price2K,
+	}
+
+	// 分组配置了 2K 价格，应该使用分组价格而不是默认的 $0.134
+	cost := svc.CalculateImageCost("gemini-3-pro-image", "2K", 1, groupConfig, 1.0)
+	require.InDelta(t, 0.20, cost.TotalCost, 0.0001)
+}
+
+// TestGetImageUnitPrice_PartialGroupConfig 测试分组部分配置时回退默认
+func TestGetImageUnitPrice_PartialGroupConfig(t *testing.T) {
+	svc := &BillingService{}
+
+	// 只配置 1K 价格
+	price1K := 0.10
+	groupConfig := &ImagePriceConfig{
+		Price1K: &price1K,
+	}
+
+	// 1K 使用分组价格
+	cost := svc.CalculateImageCost("gemini-3-pro-image", "1K", 1, groupConfig, 1.0)
+	require.InDelta(t, 0.10, cost.TotalCost, 0.0001)
+
+	// 2K 回退默认价格 $0.201 (1.5倍)
+	cost = svc.CalculateImageCost("gemini-3-pro-image", "2K", 1, groupConfig, 1.0)
+	require.InDelta(t, 0.201, cost.TotalCost, 0.0001)
+
+	// 4K 回退默认价格 $0.268 (翻倍)
+	cost = svc.CalculateImageCost("gemini-3-pro-image", "4K", 1, groupConfig, 1.0)
+	require.InDelta(t, 0.268, cost.TotalCost, 0.0001)
+}
+
+// TestGetDefaultImagePrice_FallbackHardcoded 测试 PricingService 无数据时使用硬编码默认值
+func TestGetDefaultImagePrice_FallbackHardcoded(t *testing.T) {
+	svc := &BillingService{} // pricingService 为 nil
+
+	// 1K 默认价格 $0.134，2K 默认价格 $0.201 (1.5倍)
+	cost := svc.CalculateImageCost("gemini-3-pro-image", "1K", 1, nil, 1.0)
+	require.InDelta(t, 0.134, cost.TotalCost, 0.0001)
+
+	cost = svc.CalculateImageCost("gemini-3-pro-image", "2K", 1, nil, 1.0)
+	require.InDelta(t, 0.201, cost.TotalCost, 0.0001)
+}