Merge pull request #142 from fair-workflows/fix-republishing

Add userfriendly error message in case of signing an already signed file

nanopub/java_wrapper.py

@@ -38,6 +38,13 @@ def _run_command(command):
             raise RuntimeError('Nanopub RSA key appears to be missing,\n'
                                + PROFILE_INSTRUCTIONS_MESSAGE
                                + '\nDetailed error message:\n' + stderr)
+        elif all(m in stderr for m in ['SignatureException', 'Seems to have signature']):
+            raise RuntimeError('The Publication you are trying to publish already has a signature, '
+                               'this means it is likely already published. '
+                               'If you want to publish a modified existing nanopublication '
+                               'you need to do a few extra steps before you can publish. '
+                               'See the discussion in: '
+                               'https://github.com/fair-workflows/nanopub/issues/110')
         elif result.returncode != 0:
             raise RuntimeError(f'Error in nanopub-java when running {command}: {stderr}')
 

tests/test_java_wrapper.py

@@ -40,6 +40,15 @@ def test_sign_fails_on_invalid_nanopub(tmp_path):
         java_wrapper.sign(invalid_file)
 
 
+def test_sign_fails_on_already_signed_publication(tmp_path):
+    java_wrapper = JavaWrapper(use_test_server=True)
+    temp_signed_file = tmp_path / 'signed.trig'
+    shutil.copy(NANOPUB_SAMPLE_SIGNED, temp_signed_file)
+    with pytest.raises(RuntimeError) as e:
+        java_wrapper.sign(unsigned_file=temp_signed_file)
+    assert 'The Publication you are trying to publish already has a signature' in str(e.value)
+
+
 @pytest.mark.no_rsa_key
 def test_sign_nanopub_no_rsa_key(tmp_path):
     """Test signing when no RSA key exists, only run if RSA keys are not set up."""