Added test for v2-v1 compatibilty.

src/test/test_v2_v1_compat.py

@@ -0,0 +1,21 @@
+"""Tests for Pydantic v2-v1 compatibility."""
+
+import pytest
+
+from pydantic.version import VERSION as PYDANTIC_VERSION
+from pydantic_yaml import to_yaml_str, parse_yaml_raw_as
+
+
+@pytest.mark.skipif(PYDANTIC_VERSION < "2", reason="Only supported for Pydantic v2.")
+def test_pydantic_v2_v1_compat() -> None:
+    """Test v1-compatibility in pydantic v2."""
+    from pydantic.v1 import BaseModel
+
+    class MyModel(BaseModel):
+        """Simple model for dumping."""
+
+        v: str = "vee"
+
+    yml = to_yaml_str(MyModel(v="tree"))  # type: ignore
+    obj = parse_yaml_raw_as(MyModel, yml)  # type: ignore
+    assert obj.v == "tree"