Fix embedded struct marshalling

sheriff.go

@@ -121,7 +121,8 @@ func Marshal(options *Options, data interface{}) (interface{}, error) {
 		field := t.Field(i)
 		val := v.Field(i)
 
-		jsonTag, jsonOpts := parseTag(field.Tag.Get("json"))
+		jsonTagVal, jsonTagExists := field.Tag.Lookup("json")
+		jsonTag, jsonOpts := parseTag(jsonTagVal)
 
 		// If no json tag is provided, use the field Name
 		if jsonTag == "" {
@@ -194,7 +195,7 @@ func Marshal(options *Options, data interface{}) (interface{}, error) {
 		// when a composition field we want to bring the child
 		// nodes to the top
 		nestedVal, ok := v.(KVStore)
-		if isEmbeddedField && ok {
+		if !jsonTagExists && isEmbeddedField && ok {
 			nestedVal.Each(func(k string, v interface{}) {
 				dest.Set(k, v)
 			})

sheriff_test.go

@@ -579,14 +579,20 @@ type TestMarshal_Embedded struct {
 	Foo string `json:"foo" groups:"test"`
 }
 
+type TestMarshal_NamedEmbedded struct {
+	Qux string `json:"qux" groups:"test"`
+}
+
 type TestMarshal_EmbeddedParent struct {
 	*TestMarshal_Embedded
-	Bar string `json:"bar" groups:"test"`
+	*TestMarshal_NamedEmbedded `json:"embedded"`
+	Bar                        string `json:"bar" groups:"test"`
 }
 
 func TestMarshal_EmbeddedField(t *testing.T) {
 	v := TestMarshal_EmbeddedParent{
 		&TestMarshal_Embedded{"Hello"},
+		&TestMarshal_NamedEmbedded{"Big"},
 		"World",
 	}
 	o := &Options{Groups: []string{"test"}}
@@ -597,13 +603,24 @@ func TestMarshal_EmbeddedField(t *testing.T) {
 	actual, err := json.Marshal(actualMap)
 	assert.NoError(t, err)
 
-	expected, err := json.Marshal(map[string]interface{}{
-		"bar": "World",
-		"foo": "Hello",
+	t.Run("should match the original json marshal", func(t *testing.T) {
+		expected, err := json.Marshal(v)
+		assert.NoError(t, err)
+
+		assert.JSONEq(t, string(expected), string(actual))
 	})
-	assert.NoError(t, err)
 
-	assert.Equal(t, string(expected), string(actual))
+	t.Run("should match the expected map", func(t *testing.T) {
+		expectedMap, err := json.Marshal(map[string]interface{}{
+			"bar": "World",
+			"foo": "Hello",
+			"embedded": map[string]interface{}{
+				"qux": "Big",
+			},
+		})
+		assert.NoError(t, err)
+		assert.JSONEq(t, string(expectedMap), string(actual))
+	})
 }
 
 type TestMarshal_EmbeddedEmpty struct {