fix new test that used helpers

asdf/_tests/test_yaml.py

@@ -9,6 +9,7 @@
 import asdf
 from asdf import tagged, treeutil, yamlutil
 from asdf.exceptions import AsdfConversionWarning, AsdfWarning
+from asdf.testing.helpers import yaml_to_asdf
 
 
 def _roundtrip(obj):
@@ -334,15 +335,12 @@ class MyNDArray(np.ndarray):
     ],
 )
 def test_invalid_omap(payload):
-    test_yaml = f"""#ASDF {asdf.versioning.default_version}
-%YAML 1.1
---- !<tag:stsci.edu:asdf/core/asdf-1.1.0>
-od: !!omap
+    test_yaml = f"""od: !!omap
 {payload}
-..."""
+"""
 
     # Check that fully qualified explicit tags work
-    buff = helpers.yaml_to_asdf(test_yaml, yaml_headers=False)
+    buff = yaml_to_asdf(test_yaml)
 
     with pytest.raises(yaml.constructor.ConstructorError):
         with asdf.open(buff) as ff: