TST: Add test for inserts

integrationtests/test_issues.py

@@ -364,3 +364,5 @@ Campaign:
     recs = [ds_parent, ds_child, event, event, ds_child, event, basis, campaign]
     
     ins, ups = crawler.synchronize(crawled_data=recs, unique_names=False)
+    # There is only two datasets and one event to be inserted
+    assert len(ins) == 3