diff --git a/swh/loader/package/debian/loader.py b/swh/loader/package/debian/loader.py
--- a/swh/loader/package/debian/loader.py
+++ b/swh/loader/package/debian/loader.py
@@ -89,33 +89,11 @@
         yield release_name(version), p_info
 
     def resolve_revision_from(
-            self, known_package_artifacts: Dict, artifact_metadata: Dict) \
+            self, known_package_artifacts: Mapping,
+            artifact_metadata: Mapping) \
             -> Optional[bytes]:
-        artifacts_to_fetch = artifact_metadata['files']
-        logger.debug('k_p_artifacts: %s', known_package_artifacts)
-        logger.debug('artifacts_to_fetch: %s', artifacts_to_fetch)
-        for rev_id, known_artifacts in known_package_artifacts.items():
-            logger.debug('Revision: %s', rev_id)
-            logger.debug('Associated known_artifacts: %s', known_artifacts)
-            known_artifacts = known_artifacts['extrinsic']['raw']['files']
-            rev_found = True
-            for a_name, k_artifact in known_artifacts.items():
-                artifact_to_fetch = artifacts_to_fetch.get(a_name)
-                logger.debug('artifact_to_fetch: %s', artifact_to_fetch)
-                if artifact_to_fetch is None:
-                    # as soon as we do not see an artifact, we consider we need
-                    # to check the other revision
-                    rev_found = False
-                if k_artifact['sha256'] != artifact_to_fetch['sha256']:
-                    # Hash is different, we consider we need to check the other
-                    # revisions
-                    rev_found = False
-            if rev_found:
-                logger.debug('Existing revision %s found for new artifacts.',
-                             rev_id)
-                return rev_id
-        logger.debug('No existing revision found for the new artifacts.')
-        return None
+        return resolve_revision_from(
+            known_package_artifacts, artifact_metadata)
 
     def download_package(self, p_info: Mapping[str, Any],
                          tmpdir: str) -> List[Tuple[str, Mapping]]:
@@ -183,6 +161,42 @@
         }
 
 
+def resolve_revision_from(known_package_artifacts: Mapping,
+                          artifact_metadata: Mapping) -> Optional[bytes]:
+    """Given known package artifacts (resolved from the snapshot of previous
+    visit) and the new artifact to fetch, try to solve the corresponding
+    revision.
+
+    """
+    artifacts_to_fetch = artifact_metadata.get('files')
+    if not artifacts_to_fetch:
+        return None
+    logger.debug('k_p_artifacts: %s', known_package_artifacts)
+    logger.debug('artifacts_to_fetch: %s', artifacts_to_fetch)
+    for rev_id, known_artifacts in known_package_artifacts.items():
+        logger.debug('Revision: %s', rev_id)
+        logger.debug('Associated known_artifacts: %s', known_artifacts)
+        known_artifacts = known_artifacts['extrinsic']['raw']['files']
+        rev_found = True
+        for a_name, k_artifact in known_artifacts.items():
+            artifact_to_fetch = artifacts_to_fetch.get(a_name)
+            logger.debug('artifact_to_fetch: %s', artifact_to_fetch)
+            if artifact_to_fetch is None:
+                # as soon as we do not see an artifact, we consider we need
+                # to check the other revision
+                rev_found = False
+            if k_artifact['sha256'] != artifact_to_fetch['sha256']:
+                # Hash is different, we consider we need to check the other
+                # revisions
+                rev_found = False
+        if rev_found:
+            logger.debug('Existing revision %s found for new artifacts.',
+                         rev_id)
+            return rev_id
+    logger.debug('No existing revision found for the new artifacts.')
+    return None
+
+
 def uid_to_person(uid: str) -> Mapping[str, str]:
     """Convert an uid to a person suitable for insertion.
 
diff --git a/swh/loader/package/debian/tests/test_debian.py b/swh/loader/package/debian/tests/test_debian.py
--- a/swh/loader/package/debian/tests/test_debian.py
+++ b/swh/loader/package/debian/tests/test_debian.py
@@ -14,6 +14,7 @@
     prepare_person, get_package_metadata, extract_package
 )
 from swh.loader.package.tests.common import check_snapshot, get_stats
+from swh.loader.package.debian.loader import resolve_revision_from
 
 
 logger = logging.getLogger(__name__)
@@ -386,3 +387,68 @@
     }
 
     check_snapshot(expected_snapshot, loader.storage)
+
+
+def test_resolve_revision_from_edge_cases():
+    """Solving revision with empty data will result in unknown revision
+
+    """
+    for package_artifacts in [{}, PACKAGE_FILES]:
+        actual_revision = resolve_revision_from(
+            package_artifacts, {})
+        assert actual_revision is None
+
+    for known_artifacts in [{}, PACKAGE_FILES]:
+        actual_revision = resolve_revision_from(
+            {}, known_artifacts)
+        assert actual_revision is None
+
+    expected_revision_id = b"(\x07\xf5\xb3\xf8Ch\xb4\x88\x9a\x9a\xe8'\xfe\x85\x85O\xfe\xcf\x07"  # noqa
+
+
+def test_resolve_revision_from_edge_cases_hit_and_miss():
+    """Solving revision with inconsistent data will result in unknown revision
+
+    """
+    artifact_metadata = PACKAGE_FILES2
+    expected_revision_id = b"(\x07\xf5\xb3\xf8Ch\xb4\x88\x9a\x9a\xe8'\xfe\x85\x85O\xfe\xcf\x07"  # noqa
+    known_package_artifacts = {
+        expected_revision_id: {
+            'extrinsic': {
+                'provider': 'http://deb.debian.org/debian/pool/contrib/c/cicero/cicero_0.7.2-3.dsc',  # noqa
+                'raw': PACKAGE_FILES,
+                'when': '2019-12-19T17:04:32.161965+00:00'
+            },
+            # ... removed the unnecessary intermediary data
+        }
+    }
+
+    actual_revision = resolve_revision_from(
+        known_package_artifacts, artifact_metadata
+    )
+
+    assert actual_revision is None
+
+
+def test_resolve_revision_from():
+    """Solving revision with consistent data will solve the revision
+
+    """
+    artifact_metadata = PACKAGE_FILES
+    expected_revision_id = b"(\x07\xf5\xb3\xf8Ch\xb4\x88\x9a\x9a\xe8'\xfe\x85\x85O\xfe\xcf\x07"  # noqa
+    known_package_artifacts = {
+        expected_revision_id: {
+            'extrinsic': {
+                'provider': 'http://deb.debian.org/debian/pool/contrib/c/cicero/cicero_0.7.2-3.dsc',  # noqa
+                'raw': PACKAGE_FILES,
+                'when': '2019-12-19T17:04:32.161965+00:00'
+            },
+            # ... removed the unnecessary intermediary data
+        }
+    }
+
+    actual_revision = resolve_revision_from(
+        known_package_artifacts, artifact_metadata
+    )
+
+    assert actual_revision == expected_revision_id