[issues-391] Fix document typecheck in encoding for nested types (#394)

* [issues-391] Fix document typecheck in encoding  for nested types

This resolves #391
where encoding of document types
is not checking to see if nested types at every layer
are explicitly marked for no serialization or deserialization.
I moved the check into the recursive layer that way every
nested type would get checked. This mimics how
decoding is correctly handling this issue.

.changelog/52ea7af068da449f918698755a7d0f01.json

@@ -0,0 +1,8 @@
+{
+    "id": "52ea7af0-68da-449f-9186-98755a7d0f01",
+    "type": "bugfix",
+    "description": "fixed document type checking for encoding nested types",
+    "modules": [
+        "."
+    ]
+}

document/json/encoder.go

@@ -20,10 +20,6 @@ type Encoder struct {
 
 // Encode returns the JSON encoding of v.
 func (e *Encoder) Encode(v interface{}) ([]byte, error) {
-	if document.IsNoSerde(v) {
-		return nil, fmt.Errorf("unsupported type: %v", v)
-	}
-
 	encoder := smithyjson.NewEncoder()
 
 	if err := e.encode(jsonValueProvider(encoder.Value), reflect.ValueOf(v), serde.Tag{}); err != nil {
@@ -137,6 +133,13 @@ func (e *Encoder) encodeZeroValue(vp valueProvider, rv reflect.Value) error {
 }
 
 func (e *Encoder) encodeStruct(vp valueProvider, rv reflect.Value) error {
+	if rv.CanInterface() && document.IsNoSerde(rv.Interface()) {
+		return &document.UnmarshalTypeError{
+			Value: fmt.Sprintf("unsupported type"),
+			Type:  rv.Type(),
+		}
+	}
+
 	switch {
 	case rv.Type().ConvertibleTo(serde.ReflectTypeOf.Time):
 		return &document.InvalidMarshalError{
@@ -323,4 +326,4 @@ func isValidJSONNumber(s string) bool {
 
 	// Make sure we are at the end.
 	return s == ""
-}
+}

document/json/encoder_test.go

@@ -1,6 +1,7 @@
 package json_test
 
 import (
+	"github.com/aws/smithy-go/document"
 	"github.com/aws/smithy-go/document/internal/serde"
 	"github.com/aws/smithy-go/document/json"
 	"github.com/google/go-cmp/cmp"
@@ -41,10 +42,20 @@ func TestEncoder_Encode(t *testing.T) {
 
 func TestNewEncoderUnsupportedTypes(t *testing.T) {
 	type customTime time.Time
+	type noSerde = document.NoSerde
+	type NestedThing struct {
+		SomeThing string
+		noSerde
+	}
+	type Thing struct {
+		OtherThing  string
+		NestedThing NestedThing
+	}
 
 	cases := []interface{}{
 		time.Now().UTC(),
 		customTime(time.Now().UTC()),
+		Thing{OtherThing: "foo", NestedThing: NestedThing{SomeThing: "bar"}},
 	}
 
 	encoder := json.NewEncoder()