fix tinygo build; add tinygo test to test pipeline if available

x/xnet/xnet_tinygo_test.go

@@ -0,0 +1,22 @@
+//go:build !tinygo
+
+// Exclude tinygo compiler from build since exec package and t.Skip() are unimplemented.
+// Also: wouldn't including tinygo cause a recursive call to tinygo test?
+package xnet
+
+import (
+	"os/exec"
+	"testing"
+)
+
+func TestTinyGoTest(t *testing.T) {
+	if exec.Command("tinygo", "version").Run() != nil {
+		t.Skip("tinygo not installed")
+	}
+	// This takes a long time. Consider running only important
+	// tests with -run=TestXxx flag: `go test ./... -run=TestXxx`
+	out, err := exec.Command("tinygo", "test", ".").CombinedOutput()
+	if err != nil {
+		t.Fatal("tinygo failed to test:", err, "\n", string(out))
+	}
+}