diff --git a/dandi/consts.py b/dandi/consts.py
index ff065e7cc..5518d8d38 100644
--- a/dandi/consts.py
+++ b/dandi/consts.py
@@ -27,6 +27,7 @@
     "genotype",
     "sex",
     "species",
+    "strain",
     "subject_id",
 )
 
diff --git a/dandi/pytest_plugin.py b/dandi/pytest_plugin.py
index 26ad6da21..e78577bb7 100644
--- a/dandi/pytest_plugin.py
+++ b/dandi/pytest_plugin.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from dandischema.models import DandiBaseModel
 from pytest import Config, Item, Parser
 
 from .tests.fixtures import *  # noqa: F401, F403  # lgtm [py/polluting-import]
@@ -28,9 +29,7 @@ def pytest_configure(config):
         "ai_generated",
     ]
     for marker in markers:
-        config.addinivalue_line(
-            "markers", marker
-        )
+        config.addinivalue_line("markers", marker)
 
 
 def pytest_collection_modifyitems(items: list[Item], config: Config) -> None:
@@ -46,3 +45,24 @@ def pytest_collection_modifyitems(items: list[Item], config: Config) -> None:
                 deselected_items.append(item)
         config.hook.pytest_deselected(items=deselected_items)
         items[:] = selected_items
+
+
+def pytest_assertrepr_compare(op, left, right):
+    """Custom comparison representation for your classes."""
+    if (
+        isinstance(left, DandiBaseModel)
+        and isinstance(right, DandiBaseModel)
+        and op == "=="
+    ):
+        ldict, rdict = dict(left), dict(right)
+        if ldict == rdict:
+            return [
+                "dict representations of models are equal, but values aren't!",
+                f"Left: {left!r}",
+                f"Right: {right!r}",
+            ]
+        else:
+            # Rely on pytest just "recursing" into interpreting the dict fails
+            # TODO: could be further improved by account for ANY values etc
+            assert ldict == rdict  # for easier comprehension of diffs
+    return None
diff --git a/dandi/tests/fixtures.py b/dandi/tests/fixtures.py
index d246109ab..541da8ac2 100644
--- a/dandi/tests/fixtures.py
+++ b/dandi/tests/fixtures.py
@@ -110,6 +110,7 @@ def simple2_nwb(
             date_of_birth=datetime(2016, 12, 1, tzinfo=tzutc()),
             sex="U",
             species="Mus musculus",
+            strain="C57BL/6J",
         ),
         **simple1_nwb_metadata,
     )
diff --git a/dandi/tests/test_metadata.py b/dandi/tests/test_metadata.py
index 5c20acf0d..9754448f6 100644
--- a/dandi/tests/test_metadata.py
+++ b/dandi/tests/test_metadata.py
@@ -6,7 +6,7 @@
 import shutil
 from typing import Any
 
-from anys import ANY_AWARE_DATETIME, AnyFullmatch, AnyIn
+from anys import ANY_AWARE_DATETIME, ANY_INT, AnyFullmatch, AnyIn
 from dandischema.consts import DANDI_SCHEMA_VERSION
 from dandischema.metadata import validate
 from dandischema.models import (
@@ -24,6 +24,7 @@
     SexType,
     Software,
     SpeciesType,
+    StrainType,
 )
 from dandischema.models import Dandiset as DandisetMeta
 from dateutil.tz import tzutc
@@ -873,7 +874,7 @@ def test_nwb2asset(simple2_nwb: Path) -> None:
                 ],
             ),
         ],
-        contentSize=ByteSize(19664),
+        contentSize=ANY_INT,
         encodingFormat="application/x-nwb",
         digest={DigestType.dandi_etag: "dddddddddddddddddddddddddddddddd-1"},
         path=str(simple2_nwb),
@@ -898,6 +899,7 @@ def test_nwb2asset(simple2_nwb: Path) -> None:
                     identifier="http://purl.obolibrary.org/obo/NCBITaxon_10090",
                     name="Mus musculus - House mouse",
                 ),
+                strain=StrainType(schemaKey="StrainType", name="C57BL/6J"),
             ),
         ],
         variableMeasured=[],