add TryJoinHostPort func

net/net.go

@@ -0,0 +1,21 @@
+package netutil
+
+import (
+	"errors"
+	"net"
+)
+
+var ErrMissingPort = errors.New("missing port")
+
+// TryJoinHostPort joins host and port. If port is empty, it returns host and an error.
+func TryJoinHostPort(host, port string) (string, error) {
+	if host == "" {
+		return "", &net.AddrError{Err: "missing host", Addr: host}
+	}
+
+	if port == "" {
+		return host, ErrMissingPort
+	}
+
+	return net.JoinHostPort(host, port), nil
+}

net/net_test.go

@@ -0,0 +1,57 @@
+package netutil
+
+import (
+	"testing"
+)
+
+func TestTryJoinHostPort(t *testing.T) {
+	tests := []struct {
+		name    string
+		host    string
+		port    string
+		want    string
+		wantErr bool
+	}{
+		{
+			name:    "both host and port provided",
+			host:    "localhost",
+			port:    "8080",
+			want:    "localhost:8080",
+			wantErr: false,
+		},
+		{
+			name:    "empty host",
+			host:    "",
+			port:    "8080",
+			want:    "",
+			wantErr: true,
+		},
+		{
+			name:    "empty port",
+			host:    "localhost",
+			port:    "",
+			want:    "localhost",
+			wantErr: true,
+		},
+		{
+			name:    "both host and port empty",
+			host:    "",
+			port:    "",
+			want:    "",
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := TryJoinHostPort(tt.host, tt.port)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("TryJoinHostPort() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if got != tt.want {
+				t.Errorf("TryJoinHostPort() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}