chore: add tests for examples

examples/testutils/net.go

@@ -0,0 +1,37 @@
+package testutils
+
+import (
+	"fmt"
+	"net"
+	"testing"
+)
+
+// FindFreePort attempts to find an unused tcp port
+func FindFreePort(t *testing.T, host string, maxAttempts int) (int, error) {
+	t.Helper()
+
+	if host == "" {
+		host = "localhost"
+	}
+
+	for i := 0; i < maxAttempts; i++ {
+		addr, err := net.ResolveTCPAddr("tcp", net.JoinHostPort(host, "0"))
+		if err != nil {
+			t.Logf("unable to resolve tcp addr: %v", err)
+			continue
+		}
+		l, err := net.ListenTCP("tcp", addr)
+		if err != nil {
+			l.Close()
+			t.Logf("unable to listen on addr %q: %v", addr, err)
+			continue
+		}
+
+		port := l.Addr().(*net.TCPAddr).Port
+		l.Close()
+		return port, nil
+
+	}
+
+	return 0, fmt.Errorf("no free port found")
+}