fix failing test test_pipeline_with_documents (#506)

#505 did not work out as expected, so we need to try again.

Note that this test fails **only on the main branch CI**, since it is
(was) marked as `slow`. unfortunately, I can not reproduce locally.

TODO:
- [x] temporarily make `test_pipeline_with_documents` not slow to run it
in PR CI: does not fail here either
 - [x] investigate further
 - [ ] make `test_pipeline_with_documents` slow again

Author: ArneBinder

tests/test_pipeline.py

@@ -91,7 +91,10 @@ def mock_model(monkeypatch, documents, prepared_taskmodule):
 @pytest.mark.slow
 @pytest.mark.parametrize("inplace", [False, True])
 def test_pipeline_with_document(documents, prepared_taskmodule, mock_model, inplace):
-    document = documents[1]
+    # make a copy to ensure original documents are not modified in non-inplace mode
+    document = documents[1].copy()
+    assert len(document.entities.predictions) == 0, "Document should not have predictions yet"
+
     pipeline = PyTorchIEPipeline(model=mock_model, taskmodule=prepared_taskmodule, device=-1)
 
     returned_document = pipeline(document, inplace=inplace)
@@ -111,6 +114,10 @@ def test_pipeline_with_document(documents, prepared_taskmodule, mock_model, inpl
 def test_pipeline_with_documents(documents, prepared_taskmodule, mock_model, inplace):
     # make a copy to ensure original documents are not modified in non-inplace mode
     documents = [doc.copy() for doc in documents]
+    assert all(
+        len(doc.entities.predictions) == 0 for doc in documents
+    ), "Documents should not have predictions yet"
+
     pipeline = PyTorchIEPipeline(model=mock_model, taskmodule=prepared_taskmodule, device=-1)
 
     returned_documents = pipeline(documents, inplace=inplace)