refactor: 封装 Redis key 生成函数

backend/internal/repository/billing_cache_test.go

@@ -0,0 +1,87 @@
+//go:build unit
+
+package repository
+
+import (
+	"math"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestBillingBalanceKey(t *testing.T) {
+	tests := []struct {
+		name     string
+		userID   int64
+		expected string
+	}{
+		{
+			name:     "normal_user_id",
+			userID:   123,
+			expected: "billing:balance:123",
+		},
+		{
+			name:     "zero_user_id",
+			userID:   0,
+			expected: "billing:balance:0",
+		},
+		{
+			name:     "negative_user_id",
+			userID:   -1,
+			expected: "billing:balance:-1",
+		},
+		{
+			name:     "max_int64",
+			userID:   math.MaxInt64,
+			expected: "billing:balance:9223372036854775807",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			got := billingBalanceKey(tc.userID)
+			require.Equal(t, tc.expected, got)
+		})
+	}
+}
+
+func TestBillingSubKey(t *testing.T) {
+	tests := []struct {
+		name     string
+		userID   int64
+		groupID  int64
+		expected string
+	}{
+		{
+			name:     "normal_ids",
+			userID:   123,
+			groupID:  456,
+			expected: "billing:sub:123:456",
+		},
+		{
+			name:     "zero_ids",
+			userID:   0,
+			groupID:  0,
+			expected: "billing:sub:0:0",
+		},
+		{
+			name:     "negative_ids",
+			userID:   -1,
+			groupID:  -2,
+			expected: "billing:sub:-1:-2",
+		},
+		{
+			name:     "max_int64_ids",
+			userID:   math.MaxInt64,
+			groupID:  math.MaxInt64,
+			expected: "billing:sub:9223372036854775807:9223372036854775807",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			got := billingSubKey(tc.userID, tc.groupID)
+			require.Equal(t, tc.expected, got)
+		})
+	}
+}