Add a test for post_dump

see #125

Author: lovasoa

tests/test_postdump.py

@@ -0,0 +1,57 @@
+import typing as T
+from dataclasses import field
+
+import marshmallow as mm
+import marshmallow_dataclass as mmdc
+import collections.abc
+import unittest
+
+
+# Test from https://github.com/lovasoa/marshmallow_dataclass/issues/125
+class TestPostDump(unittest.TestCase):
+    def setUp(self) -> None:
+        class BaseSchema(mm.Schema):
+            SKIP_VALUES = {None}
+
+            @mm.post_dump
+            def remove_skip_values(self, data, many):
+                return {
+                    key: value
+                    for key, value in data.items()
+                    if not isinstance(value, collections.abc.Hashable)
+                    or value not in self.SKIP_VALUES
+                }
+
+        @mmdc.add_schema(base_schema=BaseSchema)
+        @mmdc.dataclass
+        class Item:
+            key: str
+            val: str
+            Schema: T.ClassVar[T.Type[mm.Schema]] = mm.Schema
+
+        @mmdc.add_schema(base_schema=BaseSchema)
+        @mmdc.dataclass
+        class Items:
+            other: T.Optional[str]
+            items: T.List[Item] = field(default_factory=list)
+            Schema: T.ClassVar[T.Type[mm.Schema]] = mm.Schema
+
+        self.BaseSchema = BaseSchema
+        self.Item = Item
+        self.Items = Items
+        self.data = {"items": [{"key": "any key", "val": "any value"}]}
+
+    def test_class_schema(self):
+        items_schema = mmdc.class_schema(self.Items, base_schema=self.BaseSchema)()
+        items = items_schema.load(self.data)
+        self.assertEqual(
+            {"items": [{"key": "any key", "val": "any value"}]},
+            items_schema.dump(items),
+        )
+
+    def test_inside_schema(self):
+        items = self.Items.Schema().load(self.data)
+        self.assertEqual(
+            {"items": [{"key": "any key", "val": "any value"}]},
+            self.Items.Schema().dump(items),
+        )