diff --git a/swh/provenance/tests/mongo/test_backend.py b/swh/provenance/tests/mongo/test_backend.py
new file mode 100644
--- /dev/null
+++ b/swh/provenance/tests/mongo/test_backend.py
@@ -0,0 +1,158 @@
+# Copyright (C) 2021  The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
+"""
+Unit tests for the mongo backend
+"""
+
+from datetime import datetime
+
+import pymongo.database
+import pytest
+
+from swh.provenance.mongo.backend import ProvenanceStorageMongoDb
+
+
+class TestBackend:
+    @pytest.fixture
+    def backend(self, mongodb: pymongo.database.Database):
+        return ProvenanceStorageMongoDb(mongodb)
+
+    # add content tests
+
+    def test_add_content_empty(self, backend, mongodb):
+        assert backend.content_add({}) is True
+        assert mongodb.content.count_documents({}) == 0
+
+        assert backend.content_add([]) is True
+        assert mongodb.content.count_documents({}) == 0
+
+    def test_add_content_with_insert(self, backend, mongodb):
+        # add data using add_contnet
+        # get data from mongo and compare
+        sha1 = "cf23df2207d99a74fbe169e3eba035e633b65d94"
+        data = {sha1: None}
+        assert backend.content_add(data) is True
+
+        assert mongodb.content.count_documents({}) == 1
+        cnt = mongodb.content.find_one({"sha1": sha1})
+        assert cnt["ts"] is None
+        assert cnt["revision"] == {}
+        assert cnt["directory"] == {}
+
+    def test_add_content_with_update_later_date(self, backend, mongodb):
+        sha1 = "cf23df2207d99a74fbe169e3eba035e633b65d94"
+        revision = {"test": "test"}
+        mongodb.content.insert_one(
+            {"sha1": sha1, "ts": 1631881748, "revision": revision, "directory": {}}
+        )
+
+        new_date = datetime(2010, 10, 10)
+        data = {sha1: new_date}
+        # data has a date before the one in the db
+        assert backend.content_add(data) is True
+        cnt = mongodb.content.find_one({"sha1": sha1})
+        assert cnt["ts"] == new_date.timestamp()
+        assert cnt["revision"] == revision
+        assert cnt["directory"] == {}
+
+    def test_add_content_with_update_none_date(self, backend, mongodb):
+        sha1 = "cf23df2207d99a74fbe169e3eba035e633b65d94"
+        revision = {"test": "test"}
+        mongodb.content.insert_one(
+            {"sha1": sha1, "ts": None, "revision": revision, "directory": {}}
+        )
+
+        new_date = datetime(2010, 10, 10)
+        data = {sha1: new_date}
+        # data has a date before the one in the db
+        assert backend.content_add(data) is True
+        cnt = mongodb.content.find_one({"sha1": sha1})
+        assert cnt["ts"] == new_date.timestamp()
+        assert cnt["revision"] == revision
+        assert cnt["directory"] == {}
+
+    def test_add_content_do_not_update_older_date(self, backend, mongodb):
+        sha1 = "cf23df2207d99a74fbe169e3eba035e633b65d94"
+        revision = {"test": "test"}
+        mongodb.content.insert_one(
+            {"sha1": sha1, "ts": 1286661600, "revision": revision, "directory": {}}
+        )
+
+        new_date = datetime(2020, 10, 10)
+        data = {sha1: new_date}
+        # data has a date after the one in the db
+        assert backend.content_add(data) is True
+        cnt = mongodb.content.find_one({"sha1": sha1})
+        assert cnt["ts"] == 1286661600
+
+    def test_add_content_multiple(self, backend, mongodb):
+        pass
+
+    # add directory tests
+
+    def test_add_directory_empty(self, backend, mongodb):
+        assert backend.directory_add({}) is True
+        assert mongodb.directory.count_documents({}) == 0
+
+        assert backend.directory_add([]) is True
+        assert mongodb.directory.count_documents({}) == 0
+
+    def test_add_directory_with_insert(self, backend, mongodb):
+        # add data using add_contnet
+        # get data from mongo and compare
+        sha1 = "cf23df2207d99a74fbe169e3eba035e633b65d94"
+        data = {sha1: None}
+        assert backend.directory_add(data) is True
+
+        assert mongodb.directory.count_documents({}) == 1
+        cnt = mongodb.directory.find_one({"sha1": sha1})
+        assert cnt["ts"] is None
+        assert cnt["revision"] == {}
+
+    def test_add_directory_with_update_later_date(self, backend, mongodb):
+        sha1 = "cf23df2207d99a74fbe169e3eba035e633b65d94"
+        revision = {"test": "test"}
+        mongodb.directory.insert_one(
+            {"sha1": sha1, "ts": 1631881748, "revision": revision}
+        )
+
+        new_date = datetime(2010, 10, 10)
+        data = {sha1: new_date}
+        # data has a date before the one in the db
+        assert backend.directory_add(data) is True
+        diy = mongodb.directory.find_one({"sha1": sha1})
+        assert diy["ts"] == new_date.timestamp()
+        assert diy["revision"] == revision
+
+    def test_add_directory_with_update_none_date(self, backend, mongodb):
+        sha1 = "cf23df2207d99a74fbe169e3eba035e633b65d94"
+        revision = {"test": "test"}
+        mongodb.directory.insert_one({"sha1": sha1, "ts": None, "revision": revision})
+
+        new_date = datetime(2010, 10, 10)
+        data = {sha1: new_date}
+        # data has a date before the one in the db
+        assert backend.directory_add(data) is True
+        diy = mongodb.directory.find_one({"sha1": sha1})
+        assert diy["ts"] == new_date.timestamp()
+        assert diy["revision"] == revision
+
+    def test_add_directory_do_not_update_older_date(self, backend, mongodb):
+        sha1 = "cf23df2207d99a74fbe169e3eba035e633b65d94"
+        revision = {"test": "test"}
+        mongodb.directory.insert_one(
+            {"sha1": sha1, "ts": 1286661600, "revision": revision}
+        )
+
+        new_date = datetime(2020, 10, 10)
+        data = {sha1: new_date}
+        # data has a date after the one in the db
+        assert backend.directory_add(data) is True
+        cnt = mongodb.directory.find_one({"sha1": sha1})
+        assert cnt["ts"] == 1286661600
+
+    def test_add_directory_multiple(self, backend, mongodb):
+        pass