diff --git a/tests/test_reference_files.py b/tests/test_reference_files.py
index a5dde810..3eca1649 100644
--- a/tests/test_reference_files.py
+++ b/tests/test_reference_files.py
@@ -1,13 +1,86 @@
 import os
 
+import asdf
+import numpy as np
 import pytest
-from asdf import open as asdf_open
-from asdf import versioning
-from asdf._tests._helpers import assert_tree_match
 
 _REFFILE_PATH = os.path.join(os.path.dirname(__file__), "..", "reference_files")
 
 
+def assert_tree_match(tree_a, tree_b):
+    seen = set()
+
+    def walk_trees(a, b):
+        seen_key = (id(a), id(b))
+
+        if seen_key in seen:
+            return
+
+        seen.add(seen_key)
+
+        assert isinstance(a, type(b))
+        if isinstance(a, dict):
+            assert set(a.keys()) == set(b.keys())
+            for k in a:
+                walk_trees(a[k], b[k])
+        elif isinstance(a, list):
+            assert len(a) == len(b)
+            for ai, bi in zip(a, b):
+                walk_trees(ai, bi)
+        elif isinstance(a, (np.ndarray, asdf.tags.core.ndarray.NDArrayType)):
+            np.testing.assert_array_equal(a, b)
+        else:
+            assert a == b
+
+    ignore_keys = {"asdf_library", "history"}
+    walk_trees(
+        {k: v for k, v in tree_a.items() if k not in ignore_keys},
+        {k: v for k, v in tree_b.items() if k not in ignore_keys},
+    )
+
+
+@pytest.mark.parametrize(
+    "a, b",
+    [
+        ({"l": [1, 2, 3]}, {"l": [1, 2, 3]}),
+        ({"d": {"a": 1}}, {"d": {"a": 1}}),
+        ({"ld": [{"a": 1}]}, {"ld": [{"a": 1}]}),
+        ({"ld": [{"a": 1}]}, {"ld": [{"a": 1}]}),
+        ({"dk": {"a": 1, "b": 2}}, {"dk": {"b": 2, "a": 1}}),
+        ({"a": np.arange(3)}, {"a": np.arange(3)}),
+        ({"la": [np.arange(3)]}, {"la": [np.arange(3)]}),
+        ({"i": 1}, {"i": 1}),
+        ({"s": "abc"}, {"s": "abc"}),
+        ({"f": 1.0}, {"f": 1.0}),
+        ({"i": 1}, {"i": 1, "asdf_library": None}),
+        ({"i": 1}, {"i": 1, "history": None}),
+    ],
+)
+def test_assert_tree_match(a, b):
+    assert_tree_match(a, b)
+
+
+@pytest.mark.parametrize(
+    "a, b",
+    [
+        ({"l": [1, 2, 3]}, {"l": [1, 2]}),
+        ({"l": [1, 2, 3]}, {"l": [1, 2, 4]}),
+        ({"d": {"a": 1}}, {"d": {"a": 2}}),
+        ({"d": {"a": 1}}, {"d": {"b": 1}}),
+        ({"d": {"a": 1, "b": 2}}, {"d": {"a": 1}}),
+        ({"d": {"a": 1}}, {"d": {"a": 1, "b": 2}}),
+        ({"a": np.arange(3)}, {"a": np.arange(4)}),
+        ({"la": [np.arange(3)]}, {"a": [np.arange(4)]}),
+        ({"i": 1}, {"i": 2}),
+        ({"s": "abc"}, {"s": "def"}),
+        ({"f": 1.0}, {"f": 1.1}),
+    ],
+)
+def test_assert_tree_match_fail(a, b):
+    with pytest.raises(AssertionError):
+        assert_tree_match(a, b)
+
+
 def get_test_id(reference_file_path):
     """Helper function to return the informative part of a schema path"""
     path = os.path.normpath(str(reference_file_path))
@@ -16,7 +89,7 @@ def get_test_id(reference_file_path):
 
 def collect_reference_files():
     """Function used by pytest to collect ASDF reference files for testing."""
-    for version in versioning.supported_versions:
+    for version in asdf.versioning.supported_versions:
         version_dir = os.path.join(_REFFILE_PATH, str(version))
         if os.path.exists(version_dir):
             for filename in os.listdir(version_dir):
@@ -31,10 +104,11 @@ def _compare_trees(name_without_ext):
     asdf_path = name_without_ext + ".asdf"
     yaml_path = name_without_ext + ".yaml"
 
-    with asdf_open(asdf_path) as af_handle:
+    with asdf.open(asdf_path) as af_handle:
         af_handle.resolve_references()
 
-        with asdf_open(yaml_path) as ref:
+        with asdf.open(yaml_path) as ref:
+            # TODO strip asdf_library and history
             assert_tree_match(af_handle.tree, ref.tree)