diff --git a/.github/workflows/pytest.yml b/.github/workflows/pytest.yml
new file mode 100644
index 0000000..277f51e
--- /dev/null
+++ b/.github/workflows/pytest.yml
@@ -0,0 +1,15 @@
+name: Test
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        include:
+        - os: ubuntu-latest
+
+    steps:
+    - name: Run pytest
+      uses: cclauss/GitHub-Action-for-pytest@0.5.0
\ No newline at end of file
diff --git a/pykson/__init__.py b/pykson/__init__.py
index 6df16e9..f7e52e8 100644
--- a/pykson/__init__.py
+++ b/pykson/__init__.py
@@ -623,9 +623,7 @@ def __get_fields(cls) -> List[Field]:
                 fields_list.append(field)
         for base in cls.__bases__:
             base_type_dicts = base.__dict__  # type(self).__dict__
-            for n, field in base_type_dicts.items():
-                if isinstance(field, Field):
-                    fields_list.append(field)
+            fields_list += JsonObjectMeta.__get_fields(base)
         return fields_list
 
     @staticmethod
@@ -725,18 +723,32 @@ def __init__(self, accept_unknown: bool = False, extra_attributes: Optional[List
         # Empty init will be replaced by meta class
         super(JsonObject, self).__init__()
 
+    def __str__(self):
+        return json.dumps(json.loads(Pykson().to_json(self)), indent=2, sort_keys=True)
 
 T = TypeVar('T', bound=JsonObject)
 
 
 class ObjectField(Field):
     def __set__(self, instance, value, test: bool = False):
+        if isinstance(value, dict) and issubclass(self.item_type, JsonObject):
+            super().__set__(instance, Pykson().from_json(value, self.item_type), test)
+            return
         if value is not None and not isinstance(value, self.item_type):
             raise TypeError(instance, self.name, self.item_type, value)
         super().__set__(instance, value, test)
 
-    def __init__(self, item_type: Type[T], serialized_name: Optional[str] = None, null: bool = True):
-        super(ObjectField, self).__init__(field_type=FieldType.LIST, serialized_name=serialized_name, null=null)
+    def __init__(self,
+                 item_type: Type[T],
+                 serialized_name: Optional[str] = None,
+                 null: bool = True,
+                 default_value: Optional[Any] = None):
+        super(ObjectField, self).__init__(
+            field_type=FieldType.LIST,
+            serialized_name=serialized_name,
+            null=null,
+            default_value=default_value)
+        assert default_value is None or isinstance(default_value, JsonObject)
         self.item_type = item_type
 
 
@@ -751,6 +763,9 @@ def __set__(self, instance, value, test: bool = False):
             value = []
         for item in value:
             assert item is not None, "Null item passed to ObjectListField"
+            if not isinstance(item, self.item_type) and isinstance(item, dict) and issubclass(self.item_type, JsonObject):
+                super(ObjectListField, self).__set__(instance, Pykson().from_json(value, self.item_type), test)
+                return
             assert isinstance(item, self.item_type), "ObjectListField items must be of " + str(
                 self.item_type) + ", found " + str(type(item))
         super(ObjectListField, self).__set__(instance, value, test)
@@ -1062,7 +1077,9 @@ def _to_json(self, item: Union[T, List[T]], serialized_keys_based: bool = True)
                     final_dict[field_key] = field_value
             return final_dict
 
-    def to_json(self, item: Union[T, List[T]]) -> str:
+    def to_json(self, item: Union[T, List[T]], indent: bool = True) -> str:
+        if indent:
+            return json.dumps(self._to_json(item), indent=2, sort_keys=True)
         return json.dumps(self._to_json(item))
 
     def to_dict_or_list(self, item: Union[T, List[T]]) -> Union[Dict[str, Any], List[Dict[str, Any]]]:
diff --git a/setup.py b/setup.py
index 862aec4..5be6d6d 100644
--- a/setup.py
+++ b/setup.py
@@ -7,9 +7,9 @@
     required = f.read().splitlines()
 
 setuptools.setup(name='pykson',
-                 version='0.9.9.8.7',
-                 author='Sina Rezaei',
-                 author_email='sinarezaei1991@gmail.com',
+                 version='1.0.2',
+                 author='Sina Rezaei, Patrick J. Pereira',
+                 author_email='sinarezaei1991@gmail.com, patrickelectric@gmail.com',
                  long_description_content_type="text/markdown",
                  long_description=long_description,
                  description='Pykson: A JSON Serializer/Deserializer for Python',
diff --git a/test_pykson.py b/test_pykson.py
new file mode 100644
index 0000000..2ec6ce5
--- /dev/null
+++ b/test_pykson.py
@@ -0,0 +1,20 @@
+import pykson
+
+class Class1(pykson.JsonObject):
+    variable_1 = pykson.IntegerField(default_value=1)
+
+class Class2(Class1):
+    variable_2 = pykson.IntegerField(default_value=2)
+
+class Class3(Class2):
+    variable_3 = pykson.IntegerField(default_value=3)
+
+class Class4(Class3):
+    variable_4 = pykson.IntegerField(default_value=4)
+
+def test_multiple_inheritance():
+    class4 = Class4()
+    assert class4.variable_1 == 1
+    assert class4.variable_2 == 2
+    assert class4.variable_3 == 3
+    assert class4.variable_4 == 4
\ No newline at end of file