diff --git a/config/default_test.go b/config/default_test.go
index d790fb5f..de104c2a 100644
--- a/config/default_test.go
+++ b/config/default_test.go
@@ -31,6 +31,9 @@ func (c *cfg) Validate() error {
 	if c.IntValue != 10 {
 		return fmt.Errorf("invalid IntValue %d != %d", 10, c.IntValue)
 	}
+	if c.MapValue["key1"] != true {
+		return fmt.Errorf("invalid MapValue %t != %t", true, c.MapValue["key1"])
+	}
 	return nil
 }
 
@@ -105,3 +108,19 @@ func TestValidate(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestString(t *testing.T) {
+	cfg := config.NewConfig()
+	res := cfg.String()
+	if res != "default" {
+		t.Fatalf("string value invalid: %s", res)
+	}
+}
+
+func TestName(t *testing.T) {
+	cfg := config.NewConfig()
+	res := cfg.Name()
+	if res != "" {
+		t.Fatal("name value not empty")
+	}
+}
diff --git a/flow/flow_test.go b/flow/flow_test.go
new file mode 100644
index 00000000..3adcdfff
--- /dev/null
+++ b/flow/flow_test.go
@@ -0,0 +1,36 @@
+package flow
+
+import (
+	"reflect"
+	"testing"
+)
+
+func FuzzMarshall(f *testing.F) {
+	f.Fuzz(func(t *testing.T, ref []byte) {
+		rm := RawMessage(ref)
+
+		b, err := rm.MarshalJSON()
+		if err != nil {
+			t.Errorf("Error MarshalJSON: %s", err)
+		}
+
+		if !reflect.DeepEqual(ref, b) {
+			t.Errorf("Error. Expected '%s', was '%s'", ref, b)
+		}
+	})
+}
+
+func FuzzUnmarshall(f *testing.F) {
+	f.Fuzz(func(t *testing.T, ref string) {
+		b := []byte(ref)
+		rm := RawMessage(b)
+
+		if err := rm.UnmarshalJSON(b); err != nil {
+			t.Errorf("Error UnmarshalJSON: %s", err)
+		}
+
+		if ref != string(rm) {
+			t.Errorf("Error. Expected '%s', was '%s'", ref, rm)
+		}
+	})
+}