fix gravatar url is invalid when email contains upper characters

pkg/utils/avatar.go

@@ -1,11 +1,16 @@
 package utils
 
-import "fmt"
+import (
+	"fmt"
+	"strings"
+)
 
 const gravatarUrlFormat = "https://www.gravatar.com/avatar/%s"
 
 // GetGravatarUrl returns the Gravatar url according to the specified user email address
 func GetGravatarUrl(email string) string {
+	email = strings.TrimSpace(email)
+	email = strings.ToLower(email)
 	emailMd5 := MD5EncodeToString([]byte(email))
 	return fmt.Sprintf(gravatarUrlFormat, emailMd5)
 }

pkg/utils/avatar_test.go

@@ -0,0 +1,14 @@
+package utils
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetGravatarUrl(t *testing.T) {
+	// Reference: https://en.gravatar.com/site/implement/hash/
+	expectedValue := "https://www.gravatar.com/avatar/0bc83cb571cd1c50ba6f3e8a78ef1346"
+	actualValue := GetGravatarUrl("MyEmailAddress@example.com")
+	assert.Equal(t, expectedValue, actualValue)
+}