pip-audit: 0.0.4 test failure: fixture 'vuln_service' not found

When running the self tests for pip-audit-0.0.4 using py.test, I see:

___________________________________________________________ ERROR at setup of test_audit ___________________________________________________________
file /scratch/wip/py-pip-audit/work/pip-audit-0.0.4/test/test_audit.py, line 10
  def test_audit(vuln_service, dep_source):                                                                                                         
E       fixture 'vuln_service' not found                                  
>       available fixtures: cache, capfd, capfdbinary, caplog, capsys, capsysbinary, doctest_namespace, monkeypatch, pytestconfig, record_property, 
record_testsuite_property, record_xml_attribute, recwarn, tmp_path, tmp_path_factory, tmpdir, tmpdir_factory                                        
>       use 'pytest --fixtures [testpath]' for help on them.              
                                                                                                                                                    
/scratch/wip/py-pip-audit/work/pip-audit-0.0.4/test/test_audit.py:10                                                                                
_______________________________________________________ ERROR at setup of test_audit_dry_run _______________________________________________________
file /scratch/wip/py-pip-audit/work/pip-audit-0.0.4/test/test_audit.py, line 32                                                                     
  def test_audit_dry_run(monkeypatch, vuln_service, dep_source):                                                                                    
E       fixture 'vuln_service' not found                                                                                                            
>       available fixtures: cache, capfd, capfdbinary, caplog, capsys, capsysbinary, doctest_namespace, monkeypatch, pytestconfig, record_property, 
record_testsuite_property, record_xml_attribute, recwarn, tmp_path, tmp_path_factory, tmpdir, tmpdir_factory
>       use 'pytest --fixtures [testpath]' for help on them.                                                                                        
                                                                                                                                                    
/scratch/wip/py-pip-audit/work/pip-audit-0.0.4/test/test_audit.py:32