more testing around default field deletion

core/dbt/artifacts/README.md

@@ -35,9 +35,11 @@ All existing resources are defined under `dbt/artifacts/resources/v1`.
 Freely make incremental, non-breaking changes in-place to the latest major version of any artifact in mantle (via minor or patch bumps). The only changes that are fully forward and backward compatible are: 
 1. Adding a new field with a default
 2. Deleting a field with a default
-  * This is compatible in terms of serialization and deserialization in mashumaro, but still may be surprising for consumers relying on the fields existence (e.g. `manifest["deleted_field]` will stop working unless the access was implemented safely )
+  * This is compatible in terms of serialization and deserialization, but still may be lead to suprising behaviour:
+    * For artifact consumers relying on the fields existence (e.g. `manifest["deleted_field"]` will stop working unless the access was implemented safely)
+    * Old code (e.g. in dbt-core) that relies on the value of the deleted field may have surprising behaviour given only the default value will be set when instantiated from the new schema
 
-These types of minor, non-reabking changes are tested by [tests/unit/artifacts/test_base_resource.py::TestMinorSchemaChange](https://github.com/dbt-labs/dbt-core/blob/main/tests/unit/artifacts/test_base_resource.py).
+These types of minor, non-breaking changes are tested by [tests/unit/artifacts/test_base_resource.py::TestMinorSchemaChange](https://github.com/dbt-labs/dbt-core/blob/main/tests/unit/artifacts/test_base_resource.py).
 
 ### Breaking changes
 A breaking change is anything that: 

tests/unit/artifacts/test_base_resource.py

@@ -7,7 +7,7 @@
 
 @dataclass
 class BaseResourceWithDefaultField(BaseResource):
-    new_field_with_default: bool = True
+    field_with_default: bool = True
 
 
 class TestMinorSchemaChange:
@@ -31,7 +31,7 @@ def base_resource_new_default_field(self):
             path="test_path",
             original_file_path="test_original_file_path",
             unique_id="test_unique_id",
-            new_field_with_default=False,
+            field_with_default=False,
         )
 
     def test_serializing_new_default_field_is_backward_compatabile(
@@ -46,7 +46,9 @@ def test_serializing_new_default_field_is_forward_compatible(self, base_resource
 
     def test_serializing_removed_default_field_is_backward_compatabile(self, base_resource):
         # old code (using old class with default field) can create an instance of itself given new data (class w/o default field)
-        BaseResourceWithDefaultField.from_dict(base_resource.to_dict())
+        old_resource = BaseResourceWithDefaultField.from_dict(base_resource.to_dict())
+        # set to the default value when not provided in data
+        assert old_resource.field_with_default is True
 
     def test_serializing_removed_default_field_is_forward_compatible(
         self, base_resource_new_default_field