diff --git a/internal/processor/test/mqtt-message-encode_test.go b/internal/processor/test/mqtt-message-encode_test.go
index 0ea170c..76e14cc 100644
--- a/internal/processor/test/mqtt-message-encode_test.go
+++ b/internal/processor/test/mqtt-message-encode_test.go
@@ -1,8 +1,10 @@
 package processor_test
 
 import (
+	"slices"
 	"testing"
 
+	mqtt "github.com/eclipse/paho.mqtt.golang"
 	"github.com/jwetzell/showbridge-go/internal/config"
 	"github.com/jwetzell/showbridge-go/internal/processor"
 )
@@ -25,3 +27,63 @@ func TestMQTTMessageEncodeFromRegistry(t *testing.T) {
 		t.Fatalf("mqtt.message.encode processor has wrong type: %s", processorInstance.Type())
 	}
 }
+
+func TestGoodMQTTMessageEncode(t *testing.T) {
+	stringEncoder := processor.MQTTMessageEncode{}
+	tests := []struct {
+		name     string
+		payload  mqtt.Message
+		expected []byte
+	}{
+		{
+			name:     "basic string",
+			payload:  processor.NewMQTTMessage("test/topic", 1, true, []byte("hello")),
+			expected: []byte{0x68, 0x65, 0x6c, 0x6c, 0x6f},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			got, err := stringEncoder.Process(t.Context(), test.payload)
+
+			gotBytes, ok := got.([]byte)
+			if !ok {
+				t.Fatalf("mqtt.message.encode returned a %T payload: %s", got, got)
+			}
+			if err != nil {
+				t.Fatalf("mqtt.message.encode failed: %s", err)
+			}
+			if !slices.Equal(gotBytes, test.expected) {
+				t.Fatalf("mqtt.message.encode got %s, expected %s", got, test.expected)
+			}
+		})
+	}
+}
+
+func TestBadMQTTMessageEncode(t *testing.T) {
+	stringEncoder := processor.MQTTMessageEncode{}
+	tests := []struct {
+		name        string
+		payload     any
+		errorString string
+	}{
+		{
+			name:        "non-mqtt message input",
+			payload:     []byte{0x68, 0x65, 0x6c, 0x6c, 0x6f},
+			errorString: "mqtt.message.encode processor only accepts an mqtt.Message",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			got, err := stringEncoder.Process(t.Context(), test.payload)
+
+			if err == nil {
+				t.Fatalf("mqtt.message.encode expected to fail but got payload: %s", got)
+			}
+			if err.Error() != test.errorString {
+				t.Fatalf("mqtt.message.encode got error '%s', expected '%s'", err.Error(), test.errorString)
+			}
+		})
+	}
+}