diff --git a/swh/loader/package/archive/tests/test_archive.py b/swh/loader/package/archive/tests/test_archive.py
--- a/swh/loader/package/archive/tests/test_archive.py
+++ b/swh/loader/package/archive/tests/test_archive.py
@@ -82,7 +82,7 @@
 
 # hash is different then before as we changed the snapshot
 # gnu used to use `release/` (singular) instead of plural
-_expected_new_snapshot_first_visit_id = (
+_expected_new_snapshot_first_visit_id = hash_to_bytes(
     "c419397fd912039825ebdbea378bc6283f006bf5"  # noqa
 )
 
@@ -164,7 +164,8 @@
     actual_load_status = loader.load()
     assert actual_load_status["status"] == "eventful"
     assert (
-        actual_load_status["snapshot_id"] == _expected_new_snapshot_first_visit_id
+        hash_to_bytes(actual_load_status["snapshot_id"])
+        == _expected_new_snapshot_first_visit_id
     )  # noqa
 
     assert_last_visit_matches(loader.storage, URL, status="full", type="tar")
diff --git a/swh/loader/package/cran/tests/test_cran.py b/swh/loader/package/cran/tests/test_cran.py
--- a/swh/loader/package/cran/tests/test_cran.py
+++ b/swh/loader/package/cran/tests/test_cran.py
@@ -176,7 +176,7 @@
     }
 
     expected_snapshot = {
-        "id": expected_snapshot_id,
+        "id": hash_to_bytes(expected_snapshot_id),
         "branches": {
             b"HEAD": {"target": b"releases/2.22-6", "target_type": "alias"},
             b"releases/2.22-6": {
@@ -233,7 +233,7 @@
     }
 
     expected_snapshot = {
-        "id": expected_snapshot_id,
+        "id": hash_to_bytes(expected_snapshot_id),
         "branches": {
             b"HEAD": {"target": b"releases/2.22-6", "target_type": "alias"},
             b"releases/2.22-6": {
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
@@ -134,7 +134,7 @@
     } == stats
 
     expected_snapshot = {
-        "id": expected_snapshot_id,
+        "id": hash_to_bytes(expected_snapshot_id),
         "branches": {
             b"releases/stretch/contrib/0.7.2-3": {
                 "target_type": "revision",
@@ -179,7 +179,7 @@
     } == stats
 
     expected_snapshot = {
-        "id": expected_snapshot_id,
+        "id": hash_to_bytes(expected_snapshot_id),
         "branches": {
             b"releases/stretch/contrib/0.7.2-3": {
                 "target_type": "revision",
@@ -381,7 +381,7 @@
     assert_last_visit_matches(loader.storage, url, status="full", type="deb")
 
     expected_snapshot = {
-        "id": expected_snapshot_id,
+        "id": hash_to_bytes(expected_snapshot_id),
         "branches": {
             b"releases/stretch/contrib/0.7.2-3": {
                 "target_type": "revision",
diff --git a/swh/loader/package/deposit/tests/test_deposit.py b/swh/loader/package/deposit/tests/test_deposit.py
--- a/swh/loader/package/deposit/tests/test_deposit.py
+++ b/swh/loader/package/deposit/tests/test_deposit.py
@@ -174,7 +174,7 @@
     }
 
     expected_snapshot = {
-        "id": expected_snapshot_id,
+        "id": hash_to_bytes(expected_snapshot_id),
         "branches": expected_branches,
     }
     check_snapshot(expected_snapshot, storage=loader.storage)
@@ -249,7 +249,7 @@
         b"HEAD": {"target": hash_to_bytes(revision_id), "target_type": "revision"}
     }
     expected_snapshot = {
-        "id": expected_snapshot_id,
+        "id": hash_to_bytes(expected_snapshot_id),
         "branches": expected_branches,
     }
 
diff --git a/swh/loader/package/nixguix/tests/test_nixguix.py b/swh/loader/package/nixguix/tests/test_nixguix.py
--- a/swh/loader/package/nixguix/tests/test_nixguix.py
+++ b/swh/loader/package/nixguix/tests/test_nixguix.py
@@ -198,7 +198,7 @@
         },
     }
     expected_snapshot = {
-        "id": expected_snapshot_id,
+        "id": hash_to_bytes(expected_snapshot_id),
         "branches": expected_branches,
     }
     snapshot = check_snapshot(expected_snapshot, storage=loader.storage)
@@ -245,7 +245,7 @@
     }
 
     expected_snapshot = {
-        "id": expected_snapshot_id,
+        "id": hash_to_bytes(expected_snapshot_id),
         "branches": expected_branches,
     }
     snapshot = check_snapshot(expected_snapshot, storage=loader.storage)
@@ -292,7 +292,7 @@
     }
 
     expected_snapshot = {
-        "id": expected_snapshot_id,
+        "id": hash_to_bytes(expected_snapshot_id),
         "branches": expected_branches,
     }
     snapshot = check_snapshot(expected_snapshot, storage=loader.storage)
@@ -347,7 +347,7 @@
     }
 
     expected_snapshot = {
-        "id": "0c5881c74283793ebe9a09a105a9381e41380383",
+        "id": hash_to_bytes("0c5881c74283793ebe9a09a105a9381e41380383"),
         "branches": expected_branches,
     }
 
@@ -374,7 +374,7 @@
         },
     }
     expected_snapshot = {
-        "id": "4257fa2350168c6bfec726a06452ea27a2c0cb33",
+        "id": hash_to_bytes("4257fa2350168c6bfec726a06452ea27a2c0cb33"),
         "branches": expected_branches,
     }
 
@@ -426,7 +426,7 @@
         },
     }
     expected_snapshot = {
-        "id": expected_snapshot_id,
+        "id": hash_to_bytes(expected_snapshot_id),
         "branches": expected_branches,
     }
 
diff --git a/swh/loader/package/npm/tests/test_npm.py b/swh/loader/package/npm/tests/test_npm.py
--- a/swh/loader/package/npm/tests/test_npm.py
+++ b/swh/loader/package/npm/tests/test_npm.py
@@ -323,7 +323,7 @@
     )
 
     expected_snapshot = {
-        "id": expected_snapshot_id,
+        "id": hash_to_bytes(expected_snapshot_id),
         "branches": {
             b"HEAD": {"target": b"releases/0.0.4", "target_type": "alias"},
             b"releases/0.0.2": {
@@ -424,7 +424,7 @@
     } == stats
 
     expected_snapshot = {
-        "id": "b11ebac8c9d0c9e5063a2df693a18e3aba4b2f92",
+        "id": hash_to_bytes("b11ebac8c9d0c9e5063a2df693a18e3aba4b2f92"),
         "branches": {
             b"HEAD": {"target_type": "alias", "target": b"releases/0.1.0"},
             b"releases/0.1.0": {
@@ -514,7 +514,7 @@
 
     # no branch as one artifact without any intrinsic metadata
     expected_snapshot = {
-        "id": "1a8893e6a86f444e8be8e7bda6cb34fb1735a00e",
+        "id": hash_to_bytes("1a8893e6a86f444e8be8e7bda6cb34fb1735a00e"),
         "branches": {},
     }
     check_snapshot(expected_snapshot, loader.storage)
@@ -535,7 +535,7 @@
 
     # no branch as one artifact without any intrinsic metadata
     expected_snapshot = {
-        "id": "1a8893e6a86f444e8be8e7bda6cb34fb1735a00e",
+        "id": hash_to_bytes("1a8893e6a86f444e8be8e7bda6cb34fb1735a00e"),
         "branches": {},
     }
     check_snapshot(expected_snapshot, loader.storage)
@@ -556,7 +556,7 @@
 
     # artifact is used
     expected_snapshot = {
-        "id": "d6e08e19159f77983242877c373c75222d5ae9dd",
+        "id": hash_to_bytes("d6e08e19159f77983242877c373c75222d5ae9dd"),
         "branches": {
             b"HEAD": {"target_type": "alias", "target": b"releases/0.0.1"},
             b"releases/0.0.1": {
diff --git a/swh/loader/package/pypi/tests/test_pypi.py b/swh/loader/package/pypi/tests/test_pypi.py
--- a/swh/loader/package/pypi/tests/test_pypi.py
+++ b/swh/loader/package/pypi/tests/test_pypi.py
@@ -381,7 +381,7 @@
     }
 
     expected_snapshot = {
-        "id": expected_snapshot_id,
+        "id": hash_to_bytes(expected_snapshot_id),
         "branches": expected_branches,
     }
     check_snapshot(expected_snapshot, storage=loader.storage)
@@ -466,7 +466,7 @@
     }
 
     expected_snapshot = {
-        "id": expected_snapshot_id,
+        "id": hash_to_bytes(expected_snapshot_id),
         "branches": expected_branches,
     }
     check_snapshot(expected_snapshot, loader.storage)
@@ -516,7 +516,7 @@
     }
 
     expected_snapshot = {
-        "id": snapshot_id,
+        "id": hash_to_bytes(snapshot_id),
         "branches": expected_branches,
     }
     check_snapshot(expected_snapshot, loader.storage)
@@ -657,7 +657,7 @@
         b"HEAD": {"target": b"releases/1.3.0", "target_type": "alias",},
     }
     expected_snapshot = {
-        "id": expected_snapshot_id2,
+        "id": hash_to_bytes(expected_snapshot_id2),
         "branches": expected_branches,
     }
 
@@ -711,7 +711,7 @@
     }
 
     expected_snapshot = {
-        "id": expected_snapshot_id,
+        "id": hash_to_bytes(expected_snapshot_id),
         "branches": expected_branches,
     }
     check_snapshot(expected_snapshot, loader.storage)
@@ -825,7 +825,7 @@
     }
 
     # no branch as one artifact without any intrinsic metadata
-    expected_snapshot = {"id": expected_snapshot_id, "branches": {}}
+    expected_snapshot = {"id": hash_to_bytes(expected_snapshot_id), "branches": {}}
     check_snapshot(expected_snapshot, loader.storage)
 
     assert_last_visit_matches(loader.storage, url, status="full", type="pypi")
diff --git a/swh/loader/tests/__init__.py b/swh/loader/tests/__init__.py
--- a/swh/loader/tests/__init__.py
+++ b/swh/loader/tests/__init__.py
@@ -135,30 +135,20 @@
         needed.
 
     """
-    if isinstance(snapshot, Snapshot):
-        expected_snapshot = snapshot
-    elif isinstance(snapshot, dict):
-        # dict must be snapshot compliant
-        snapshot_dict = {"id": hash_to_bytes(snapshot["id"])}
-        branches = {}
-        for branch, target in snapshot["branches"].items():
-            if isinstance(branch, str):
-                branch = branch.encode("utf-8")
-            branches[branch] = encode_target(target)
-        snapshot_dict["branches"] = branches
-        expected_snapshot = Snapshot.from_dict(snapshot_dict)
-    else:
+    if isinstance(snapshot, dict):
+        snapshot = Snapshot.from_dict(snapshot)
+    if not isinstance(snapshot, Snapshot):
         raise AssertionError(f"variable 'snapshot' must be a snapshot: {snapshot!r}")
 
-    snapshot_dict = storage.snapshot_get(expected_snapshot.id)
+    snapshot_dict = storage.snapshot_get(snapshot.id)
     if snapshot_dict is None:
-        raise AssertionError(f"Snapshot {expected_snapshot.id.hex()} is not found")
+        raise AssertionError(f"Snapshot {snapshot.id.hex()} is not found")
 
     snapshot_dict.pop("next_branch")
     actual_snaphot = Snapshot.from_dict(snapshot_dict)
     assert isinstance(actual_snaphot, Snapshot)
 
-    assert expected_snapshot == actual_snaphot
+    assert snapshot == actual_snaphot
 
     branches_by_target_type = defaultdict(list)
     object_to_branch = {}
diff --git a/swh/loader/tests/test_init.py b/swh/loader/tests/test_init.py
--- a/swh/loader/tests/test_init.py
+++ b/swh/loader/tests/test_init.py
@@ -384,7 +384,8 @@
     }
 
     unexpected_snapshot = {
-        "id": "2498dbf535f882bc7f9a18fb16c9ad27fda7bab7",  # id is correct
+        # id is correct
+        "id": hash_to_bytes(snap_id_hex),
         "branches": {
             b"master": {
                 "target": hash_to_bytes(hash_hex),  # wrong branch
@@ -398,17 +399,15 @@
         check_snapshot(ORIGIN_VISIT, swh_storage)
 
     # 1. snapshot id is correct but branches mismatched
-    for snap_id in [snap_id_hex, snapshot.id]:
-        with pytest.raises(AssertionError, match="Differing attributes"):
-            unexpected_snapshot["id"] = snap_id
-            check_snapshot(unexpected_snapshot, swh_storage)
+    with pytest.raises(AssertionError, match="Differing attributes"):
+        unexpected_snapshot["id"] = snapshot.id
+        check_snapshot(unexpected_snapshot, swh_storage)
 
     # 2. snapshot id is not correct, it's not found in the storage
-    wrong_snap_id_hex = "999666f535f882bc7f9a18fb16c9ad27fda7bab7"
-    for snap_id in [wrong_snap_id_hex, hash_to_bytes(wrong_snap_id_hex)]:
-        unexpected_snapshot["id"] = wrong_snap_id_hex
-        with pytest.raises(AssertionError, match="is not found"):
-            check_snapshot(unexpected_snapshot, swh_storage)
+    wrong_snap_id = hash_to_bytes("999666f535f882bc7f9a18fb16c9ad27fda7bab7")
+    unexpected_snapshot["id"] = wrong_snap_id
+    with pytest.raises(AssertionError, match="is not found"):
+        check_snapshot(unexpected_snapshot, swh_storage)
 
     # 3. snapshot references an inexistent alias
     snapshot0 = Snapshot(