refactor: 封装 Redis key 生成函数

backend/internal/repository/email_cache_test.go

@@ -0,0 +1,45 @@
+//go:build unit
+
+package repository
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestVerifyCodeKey(t *testing.T) {
+	tests := []struct {
+		name     string
+		email    string
+		expected string
+	}{
+		{
+			name:     "normal_email",
+			email:    "user@example.com",
+			expected: "verify_code:user@example.com",
+		},
+		{
+			name:     "empty_email",
+			email:    "",
+			expected: "verify_code:",
+		},
+		{
+			name:     "email_with_plus",
+			email:    "user+tag@example.com",
+			expected: "verify_code:user+tag@example.com",
+		},
+		{
+			name:     "email_with_special_chars",
+			email:    "user.name+tag@sub.domain.com",
+			expected: "verify_code:user.name+tag@sub.domain.com",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			got := verifyCodeKey(tc.email)
+			require.Equal(t, tc.expected, got)
+		})
+	}
+}