add complete test coverage for string processors

internal/processor/string-decode_test.go

@@ -3,9 +3,40 @@ package processor_test
 import (
 	"testing"
 
+	"github.com/jwetzell/showbridge-go/internal/config"
 	"github.com/jwetzell/showbridge-go/internal/processor"
 )
 
+func TestStringDecodeFromRegistry(t *testing.T) {
+	registration, ok := processor.ProcessorRegistry["string.decode"]
+	if !ok {
+		t.Fatalf("string.decode processor not registered")
+	}
+
+	processorInstance, err := registration.New(config.ProcessorConfig{
+		Type: "string.decode",
+	})
+	if err != nil {
+		t.Fatalf("failed to create string.decode processor: %s", err)
+	}
+
+	if processorInstance.Type() != "string.decode" {
+		t.Fatalf("string.decode processor has wrong type: %s", processorInstance.Type())
+	}
+
+	payload := []byte{'h', 'e', 'l', 'l', 'o'}
+	expected := "hello"
+
+	got, err := processorInstance.Process(t.Context(), payload)
+	if err != nil {
+		t.Fatalf("string.decode processing failed: %s", err)
+	}
+
+	if got != expected {
+		t.Fatalf("string.decode got %+v, expected %+v", got, expected)
+	}
+}
+
 func TestGoodStringDecode(t *testing.T) {
 	stringDecoder := processor.StringDecode{}
 	tests := []struct {