feat: support new username system

user.go

@@ -81,7 +81,15 @@ type User struct {
 }
 
 // String returns a unique identifier of the form username#discriminator
+// or username only if the discriminator is "0"
 func (u *User) String() string {
+	if u.Discriminator == "0" || u.Discriminator == "" {
+		return u.Username
+	}
+
+	// The code below is a fallback to the special case for a pre-existing user
+	// before all users were migrated to the new format
+	// Notes: https://support-dev.discord.com/hc/en-us/articles/13667755828631
 	return u.Username + "#" + u.Discriminator
 }
 

user_test.go

@@ -5,12 +5,40 @@ import "testing"
 func TestUser(t *testing.T) {
 	t.Parallel()
 
-	user := &User{
-		Username:      "bob",
-		Discriminator: "8192",
+	tests := []struct {
+		name string
+		u    *User
+		want string
+	}{
+		{
+			name: "Given a user with a username and discriminator, When String() is called, Then it should return the username and discriminator",
+			u: &User{
+				Username:      "bob",
+				Discriminator: "8192",
+			},
+			want: "bob#8192",
+		},
+		{
+			name: "Given a user with a username and no discriminator, When String() is called, Then it should return the username",
+			u: &User{
+				Username: "aldiwildan",
+			},
+			want: "aldiwildan",
+		},
+		{
+			name: "Given a user with a username and a 0 discriminator, When String() is called, Then it should return the username",
+			u: &User{
+				Username:      "aldiwildan",
+				Discriminator: "0",
+			},
+			want: "aldiwildan",
+		},
 	}
-
-	if user.String() != "bob#8192" {
-		t.Errorf("user.String() == %v", user.String())
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := tt.u.String(); got != tt.want {
+				t.Errorf("User.String() = %v, want %v", got, tt.want)
+			}
+		})
 	}
 }