diff --git a/swh/deposit/tests/api/test_collection_add_to_origin.py b/swh/deposit/tests/api/test_collection_add_to_origin.py
--- a/swh/deposit/tests/api/test_collection_add_to_origin.py
+++ b/swh/deposit/tests/api/test_collection_add_to_origin.py
@@ -11,6 +11,7 @@
 from swh.deposit.config import COL_IRI, DEPOSIT_STATUS_LOAD_SUCCESS
 from swh.deposit.models import Deposit
 from swh.deposit.parsers import parse_xml
+from swh.deposit.tests.common import post_atom
 
 from ..conftest import create_deposit
 
@@ -32,9 +33,9 @@
 
     # adding a new deposit with the same external id as a completed deposit
     # creates the parenting chain
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data-with-add-to-origin"] % origin_url,
     )
 
@@ -79,9 +80,9 @@
     )
 
     # adding a new deposit with the same external id as a completed deposit
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data0"] % origin_url,
     )
 
@@ -99,9 +100,9 @@
     origin_url = "http://example.org/foo"
 
     # adding a new deposit with the same external id as a completed deposit
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data0"] % origin_url,
     )
 
@@ -124,9 +125,9 @@
 
     # adding a new deposit with the same external id as a completed deposit
     # creates the parenting chain
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data-with-both-add-to-origin-and-external-id"]
         % origin_url,
     )
@@ -143,9 +144,9 @@
     """
     origin_url = "http://example.org/foo"
 
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data-with-add-to-origin"] % origin_url,
         HTTP_IN_PROGRESS="true",
     )
diff --git a/swh/deposit/tests/api/test_collection_post_atom.py b/swh/deposit/tests/api/test_collection_post_atom.py
--- a/swh/deposit/tests/api/test_collection_post_atom.py
+++ b/swh/deposit/tests/api/test_collection_post_atom.py
@@ -21,6 +21,7 @@
 )
 from swh.deposit.models import Deposit, DepositCollection, DepositRequest
 from swh.deposit.parsers import parse_xml
+from swh.deposit.tests.common import post_atom
 from swh.deposit.utils import compute_metadata_context
 from swh.model.identifiers import SWHID, parse_swhid
 from swh.model.model import (
@@ -41,9 +42,9 @@
     """
     atom_error_with_decimal = atom_dataset["error-with-decimal"]
 
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_error_with_decimal,
         HTTP_SLUG="external-id",
         HTTP_IN_PROGRESS="false",
@@ -70,9 +71,9 @@
 
     """
     atom_content = atom_dataset["entry-data-empty-body"]
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_content,
         HTTP_SLUG="external-id",
     )
@@ -86,9 +87,9 @@
     """Posting a badly formatted atom should return a 400 response
 
     """
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data-badly-formatted"],
         HTTP_SLUG="external-id",
     )
@@ -102,9 +103,9 @@
     """Posting parsing error prone atom should return 400
 
     """
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data-parsing-error-prone"],
         HTTP_SLUG="external-id",
     )
@@ -118,9 +119,9 @@
     """Posting a badly formatted atom should return a 400 response
 
     """
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data-with-both-create-origin-and-add-to-origin"],
     )
     assert response.status_code == status.HTTP_400_BAD_REQUEST
@@ -138,9 +139,9 @@
     """
     origin_url = "http://example.org/foo"
 
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data0"] % origin_url,
         HTTP_IN_PROGRESS="true",
     )
@@ -164,9 +165,9 @@
     slug = str(uuid.uuid4())
 
     # when
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         url,
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data-no-origin-url"],
         HTTP_IN_PROGRESS="false",
         HTTP_SLUG=slug,
@@ -194,11 +195,10 @@
     mocker.patch("uuid.uuid4", return_value=slug)
 
     # when
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         url,
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data-no-origin-url"],
-        # + headers
         HTTP_IN_PROGRESS="false",
     )
 
@@ -223,11 +223,10 @@
     url = reverse(COL_IRI, args=[deposit_collection.name])
 
     # when
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         url,
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["error-with-external-identifier"] % external_id,
-        # + headers
         HTTP_IN_PROGRESS="false",
         HTTP_SLUG="something",
     )
@@ -252,12 +251,8 @@
     )
 
     # when
-    response = authenticated_client.post(
-        url,
-        content_type="application/atom+xml;type=entry",
-        data=document,
-        # + headers
-        HTTP_IN_PROGRESS="false",
+    response = post_atom(
+        authenticated_client, url, data=document, HTTP_IN_PROGRESS="false",
     )
 
     assert b"<external_identifier> is deprecated" in response.content
@@ -279,12 +274,8 @@
     )
 
     # when
-    response = authenticated_client.post(
-        url,
-        content_type="application/atom+xml;type=entry",
-        data=document,
-        # + headers
-        HTTP_IN_PROGRESS="false",
+    response = post_atom(
+        authenticated_client, url, data=document, HTTP_IN_PROGRESS="false",
     )
 
     assert b"only one may be used on a given deposit" in response.content
@@ -299,9 +290,9 @@
     with pytest.raises(DepositCollection.DoesNotExist):
         DepositCollection.objects.get(name=unknown_collection)
 
-    response = authenticated_client.post(
-        reverse(COL_IRI, args=[unknown_collection]),  # <- unknown collection
-        content_type="application/atom+xml;type=entry",
+    response = post_atom(
+        authenticated_client,
+        reverse(COL_IRI, args=[unknown_collection]),
         data=atom_dataset["entry-data0"],
         HTTP_SLUG="something",
     )
@@ -324,9 +315,9 @@
     atom_entry_data = atom_dataset["entry-data0"] % origin_url
 
     # when
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_entry_data,
         HTTP_IN_PROGRESS="false",
     )
@@ -363,9 +354,9 @@
 
     atom_entry_data = atom_dataset["codemeta-sample"] % origin_url
     # when
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_entry_data,
         HTTP_IN_PROGRESS="false",
     )
@@ -398,9 +389,9 @@
     invalid_swhid = "swh:1:dir :31b5c8cc985d190b5a7ef4878128ebfdc2358f49"
     xml_data = atom_dataset["entry-data-with-swhid"].format(swhid=invalid_swhid)
 
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=xml_data,
     )
     assert response.status_code == status.HTTP_400_BAD_REQUEST
@@ -418,9 +409,9 @@
         "entry-data-with-swhid-fail-metadata-functional-checks"
     ].format(swhid=swhid)
 
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=invalid_xml_data,
     )
     assert response.status_code == status.HTTP_400_BAD_REQUEST
@@ -489,9 +480,9 @@
     xml_data = atom_dataset["entry-data-with-swhid"].format(swhid=swhid)
     deposit_client = authenticated_client.deposit_client
 
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=xml_data,
     )
 
@@ -570,9 +561,9 @@
     """
     xml_data = atom_dataset["entry-data-with-origin-reference"].format(url=url)
     deposit_client = authenticated_client.deposit_client
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=xml_data,
     )
 
diff --git a/swh/deposit/tests/api/test_collection_reuse_slug.py b/swh/deposit/tests/api/test_collection_reuse_slug.py
--- a/swh/deposit/tests/api/test_collection_reuse_slug.py
+++ b/swh/deposit/tests/api/test_collection_reuse_slug.py
@@ -17,6 +17,7 @@
 )
 from swh.deposit.models import Deposit
 from swh.deposit.parsers import parse_xml
+from swh.deposit.tests.common import post_atom
 
 from ..conftest import create_deposit
 
@@ -26,9 +27,9 @@
 ):
     deposit = rejected_deposit
 
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(SE_IRI, args=[deposit.collection.name, deposit.id]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data1"],
         HTTP_SLUG=deposit.external_id,
     )
@@ -55,9 +56,9 @@
     origin_url = deposit_user.provider_url + deposit.external_id
 
     # adding a new deposit with the same external id
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data0"] % origin_url,
         HTTP_SLUG=deposit.external_id,
     )
@@ -86,9 +87,9 @@
 
     # adding a new deposit with the same external id as a completed deposit
     # creates the parenting chain
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data0"] % origin_url,
         HTTP_SLUG=deposit.external_id,
     )
@@ -122,9 +123,9 @@
 
     # adding a new deposit with the same external id as a completed deposit
     # creates the parenting chain
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data0"] % origin_url,
         HTTP_SLUG=deposit.external_id,
     )
@@ -169,9 +170,9 @@
     )
 
     # adding a new deposit with the same external id as a completed deposit
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data0"] % origin_url,
         HTTP_SLUG=external_id,
     )
@@ -219,9 +220,9 @@
     )
 
     # adding a new deposit with the same external id as a completed deposit
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data0"] % origin_url,
         HTTP_SLUG=deposit.external_id,
     )
diff --git a/swh/deposit/tests/api/test_deposit_update.py b/swh/deposit/tests/api/test_deposit_update.py
--- a/swh/deposit/tests/api/test_deposit_update.py
+++ b/swh/deposit/tests/api/test_deposit_update.py
@@ -18,6 +18,7 @@
     SE_IRI,
 )
 from swh.deposit.models import Deposit, DepositRequest
+from swh.deposit.tests.common import post_atom
 
 
 def test_add_both_archive_and_metadata_to_deposit(
@@ -100,12 +101,8 @@
     assert deposit.status == DEPOSIT_STATUS_PARTIAL
 
     update_uri = reverse(SE_IRI, args=[deposit_collection.name, deposit.id])
-    response = authenticated_client.post(
-        update_uri,
-        content_type="application/atom+xml;type=entry",
-        data="",
-        size=0,
-        HTTP_IN_PROGRESS=False,
+    response = post_atom(
+        authenticated_client, update_uri, data="", size=0, HTTP_IN_PROGRESS=False,
     )
 
     assert response.status_code == status.HTTP_200_OK
diff --git a/swh/deposit/tests/api/test_deposit_update_atom.py b/swh/deposit/tests/api/test_deposit_update_atom.py
--- a/swh/deposit/tests/api/test_deposit_update_atom.py
+++ b/swh/deposit/tests/api/test_deposit_update_atom.py
@@ -21,6 +21,7 @@
 )
 from swh.deposit.models import Deposit, DepositCollection, DepositRequest
 from swh.deposit.parsers import parse_xml
+from swh.deposit.tests.common import post_atom, put_atom
 from swh.model.hashutil import hash_to_bytes
 from swh.model.identifiers import parse_swhid, swhid
 from swh.model.model import (
@@ -46,9 +47,9 @@
         deposit = Deposit.objects.get(origin_url=origin_url)
 
     # when
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data1"],
         HTTP_IN_PROGRESS="True",
     )
@@ -78,11 +79,8 @@
         assert False, f"missing SE-IRI from {response_content['link']}"
 
     # when updating the first deposit post
-    response = authenticated_client.post(
-        se_iri,
-        content_type="application/atom+xml;type=entry",
-        data=atom_entry_data,
-        HTTP_IN_PROGRESS="False",
+    response = post_atom(
+        authenticated_client, se_iri, data=atom_entry_data, HTTP_IN_PROGRESS="False",
     )
 
     # then
@@ -141,10 +139,8 @@
 
     update_uri = reverse(EDIT_IRI, args=[deposit_collection.name, deposit.id])
 
-    response = authenticated_client.put(
-        update_uri,
-        content_type="application/atom+xml;type=entry",
-        data=atom_dataset["entry-data1"],
+    response = put_atom(
+        authenticated_client, update_uri, data=atom_dataset["entry-data1"],
     )
 
     assert response.status_code == status.HTTP_204_NO_CONTENT
@@ -186,9 +182,7 @@
     update_uri = reverse(SE_IRI, args=[deposit_collection.name, deposit.id])
 
     atom_entry = atom_dataset["entry-data1"]
-    response = authenticated_client.post(
-        update_uri, content_type="application/atom+xml;type=entry", data=atom_entry
-    )
+    response = post_atom(authenticated_client, update_uri, data=atom_entry)
 
     assert response.status_code == status.HTTP_201_CREATED
 
@@ -221,11 +215,7 @@
         assert True
 
     url = reverse(SE_IRI, args=[deposit_collection, unknown_deposit_id])
-    response = authenticated_client.post(
-        url,
-        content_type="application/atom+xml;type=entry",
-        data=atom_dataset["entry-data1"],
-    )
+    response = post_atom(authenticated_client, url, data=atom_dataset["entry-data1"],)
     assert response.status_code == status.HTTP_404_NOT_FOUND
     response_content = parse_xml(response.content)
     assert (
@@ -247,11 +237,7 @@
         assert True
 
     url = reverse(SE_IRI, args=[unknown_collection_name, deposit.id])
-    response = authenticated_client.post(
-        url,
-        content_type="application/atom+xml;type=entry",
-        data=atom_dataset["entry-data1"],
-    )
+    response = post_atom(authenticated_client, url, data=atom_dataset["entry-data1"],)
     assert response.status_code == status.HTTP_404_NOT_FOUND
     response_content = parse_xml(response.content)
     assert "Unknown collection name" in response_content["sword:error"]["atom:summary"]
@@ -269,11 +255,7 @@
     except Deposit.DoesNotExist:
         assert True
     url = reverse(EDIT_IRI, args=[deposit_collection.name, unknown_deposit_id])
-    response = authenticated_client.put(
-        url,
-        content_type="application/atom+xml;type=entry",
-        data=atom_dataset["entry-data1"],
-    )
+    response = put_atom(authenticated_client, url, data=atom_dataset["entry-data1"],)
     assert response.status_code == status.HTTP_404_NOT_FOUND
     response_content = parse_xml(response.content)
     assert (
@@ -311,10 +293,8 @@
     deposit = partial_deposit
     # when
     update_uri = reverse(EM_IRI, args=[deposit_collection.name, deposit.id])
-    response = authenticated_client.put(
-        update_uri,
-        content_type="application/atom+xml;type=entry",
-        data=atom_dataset["entry-data1"],
+    response = put_atom(
+        authenticated_client, update_uri, data=atom_dataset["entry-data1"],
     )
     # then
     assert response.status_code == status.HTTP_400_BAD_REQUEST
@@ -366,9 +346,9 @@
     nb_metadata = len(actual_existing_requests_metadata)
 
     update_uri = reverse(EDIT_IRI, args=[deposit_collection.name, complete_deposit.id])
-    response = authenticated_client.put(
+    response = put_atom(
+        authenticated_client,
         update_uri,
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data1"],
         HTTP_X_CHECK_SWHID=complete_deposit.swhid,
     )
@@ -452,9 +432,9 @@
     assert complete_deposit.swhid != incorrect_swhid
 
     update_uri = reverse(EDIT_IRI, args=[deposit_collection.name, complete_deposit.id])
-    response = authenticated_client.put(
+    response = put_atom(
+        authenticated_client,
         update_uri,
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data1"],
         HTTP_X_CHECK_SWHID=incorrect_swhid,
     )
@@ -477,9 +457,9 @@
 
     """
     update_uri = reverse(EDIT_IRI, args=[deposit_collection.name, complete_deposit.id])
-    response = authenticated_client.put(
+    response = put_atom(
+        authenticated_client,
         update_uri,
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data-ko"],
         HTTP_X_CHECK_SWHID=complete_deposit.swhid,
     )
@@ -504,9 +484,9 @@
     update_uri = reverse(EDIT_IRI, args=[deposit_collection.name, complete_deposit.id])
 
     atom_content = atom_dataset["entry-data-empty-body"]
-    response = authenticated_client.put(
+    response = put_atom(
+        authenticated_client,
         update_uri,
-        content_type="application/atom+xml;type=entry",
         data=atom_content,
         HTTP_X_CHECK_SWHID=complete_deposit.swhid,
     )
@@ -530,9 +510,9 @@
     """
     update_uri = reverse(EDIT_IRI, args=[deposit_collection.name, complete_deposit.id])
 
-    response = authenticated_client.put(
+    response = put_atom(
+        authenticated_client,
         update_uri,
-        content_type="application/atom+xml;type=entry",
         # no title, nor author, nor name fields
         data=atom_dataset["entry-data-fail-metadata-functional-checks"],
         HTTP_X_CHECK_SWHID=complete_deposit.swhid,
@@ -560,9 +540,9 @@
     origin_url = deposit_user.provider_url + external_id
     url = reverse(COL_IRI, args=[deposit_collection.name])
 
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         url,
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data0"] % origin_url,
         HTTP_IN_PROGRESS="true",
     )
@@ -578,11 +558,10 @@
         assert False, response_content
 
     # when
-    response = authenticated_client.put(
+    response = put_atom(
+        authenticated_client,
         edit_iri,
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["error-with-external-identifier"] % external_id,
-        # + headers
         HTTP_IN_PROGRESS="false",
     )
 
@@ -600,9 +579,9 @@
     origin_url = deposit_user.provider_url + external_id
     url = reverse(COL_IRI, args=[deposit_collection.name])
 
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         url,
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data0"] % origin_url,
         HTTP_IN_PROGRESS="true",
     )
@@ -618,11 +597,10 @@
         assert False, response_content
 
     # when
-    response = authenticated_client.put(
+    response = put_atom(
+        authenticated_client,
         edit_iri,
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data-with-origin-reference"].format(url=origin_url),
-        # + headers
         HTTP_IN_PROGRESS="false",
     )
 
diff --git a/swh/deposit/tests/api/test_deposit_update_binary.py b/swh/deposit/tests/api/test_deposit_update_binary.py
--- a/swh/deposit/tests/api/test_deposit_update_binary.py
+++ b/swh/deposit/tests/api/test_deposit_update_binary.py
@@ -18,7 +18,9 @@
     check_archive,
     create_arborescence_archive,
     post_archive,
+    post_atom,
     put_archive,
+    put_atom,
 )
 
 
@@ -123,9 +125,9 @@
     requests = list(DepositRequest.objects.filter(deposit=deposit, type="metadata"))
     assert len(requests) == 0
 
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(SE_IRI, args=[deposit_collection.name, deposit.id]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data1"],
         HTTP_SLUG=deposit.external_id,
         HTTP_IN_PROGRESS=True,
@@ -340,9 +342,9 @@
 
     # replacing metadata is no longer possible since the deposit's
     # status is ready
-    r = authenticated_client.put(
+    r = put_atom(
+        authenticated_client,
         edit_iri,
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data-deposit-binary"],
         CONTENT_LENGTH=len(atom_dataset["entry-data-deposit-binary"]),
         HTTP_SLUG=external_id,
@@ -353,9 +355,9 @@
 
     # adding new metadata is no longer possible since the
     # deposit's status is ready
-    r = authenticated_client.post(
+    r = post_atom(
+        authenticated_client,
         se_iri,
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data-deposit-binary"],
         CONTENT_LENGTH=len(atom_dataset["entry-data-deposit-binary"]),
         HTTP_SLUG=external_id,
diff --git a/swh/deposit/tests/common.py b/swh/deposit/tests/common.py
--- a/swh/deposit/tests/common.py
+++ b/swh/deposit/tests/common.py
@@ -163,3 +163,15 @@
 
 def put_archive(authenticated_client, *args, **kwargs):
     return _post_or_put_archive(authenticated_client.put, *args, **kwargs)
+
+
+def post_atom(authenticated_client, url, data, **kwargs):
+    return authenticated_client.post(
+        url, content_type="application/atom+xml;type=entry", data=data, **kwargs
+    )
+
+
+def put_atom(authenticated_client, url, data, **kwargs):
+    return authenticated_client.put(
+        url, content_type="application/atom+xml;type=entry", data=data, **kwargs
+    )
diff --git a/swh/deposit/tests/conftest.py b/swh/deposit/tests/conftest.py
--- a/swh/deposit/tests/conftest.py
+++ b/swh/deposit/tests/conftest.py
@@ -33,7 +33,11 @@
     setup_django_for,
 )
 from swh.deposit.parsers import parse_xml
-from swh.deposit.tests.common import create_arborescence_archive, post_archive
+from swh.deposit.tests.common import (
+    create_arborescence_archive,
+    post_archive,
+    post_atom,
+)
 from swh.model.identifiers import DIRECTORY, REVISION, SNAPSHOT, swhid
 from swh.scheduler import get_scheduler
 
@@ -344,9 +348,9 @@
 
     origin_url = deposit.client.provider_url + deposit.external_id
 
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(SE_IRI, args=[collection_name, deposit.id]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data0"] % origin_url,
         HTTP_IN_PROGRESS="true",
     )
@@ -420,9 +424,9 @@
     deposit_collection, authenticated_client, atom_dataset
 ):
 
-    response = authenticated_client.post(
+    response = post_atom(
+        authenticated_client,
         reverse(COL_IRI, args=[deposit_collection.name]),
-        content_type="application/atom+xml;type=entry",
         data=atom_dataset["entry-data1"],
         HTTP_SLUG="external-id-partial",
         HTTP_IN_PROGRESS=True,