diff --git a/test_checker.py b/test_checker.py
new file mode 100644
index 0000000..af28e50
--- /dev/null
+++ b/test_checker.py
@@ -0,0 +1,96 @@
+# Copyright (C) 2015-2016  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
+
+import gzip
+import tempfile
+import unittest
+
+from nose.tools import istest
+from nose.plugins.attrib import attr
+
+from swh.core import hashutil
+from swh.storage.objstorage.objstorage import _obj_path
+from swh.storage.checker.checker import ContentChecker
+
+
+class MockBackupStorage():
+
+    def __init__(self):
+        self.values = {}
+
+    def content_add(self, id, value):
+        self.values[id] = value
+
+    def content_get(self, ids):
+        for id in ids:
+            try:
+                data = self.values[id]
+            except KeyError:
+                yield None
+                continue
+
+            yield {'sha1': id, 'data': data}
+
+
+@attr('fs')
+class TestChecker(unittest.TestCase):
+    """ Test the content integrity checker
+    """
+
+    def setUp(self):
+        super().setUp()
+        # Connect to an objstorage
+        config = {'batch_size': 10}
+        path = tempfile.mkdtemp()
+        depth = 3
+        self.checker = ContentChecker(config, path, depth, 'http://None')
+        self.checker.backup_storage = MockBackupStorage()
+
+    def corrupt_content(self, id):
+        """ Make the given content invalid.
+        """
+        hex_id = hashutil.hash_to_hex(id)
+        file_path = _obj_path(hex_id, self.checker.objstorage._root_dir, 3)
+        with gzip.open(file_path, 'wb') as f:
+            f.write(b'Unexpected content')
+
+    @istest
+    def check_valid_content(self):
+        # Check that a valid content is valid.
+        content = b'check_valid_content'
+        id = self.checker.objstorage.add_bytes(content)
+        self.assertTrue(self.checker.check_content(id))
+
+    @istest
+    def check_invalid_content(self):
+        # Check that an invalid content is noticed.
+        content = b'check_invalid_content'
+        id = self.checker.objstorage.add_bytes(content)
+        self.corrupt_content(id)
+        self.assertFalse(self.checker.check_content(id))
+
+    @istest
+    def repair_content_present(self):
+        # Try to repair a content that is in the backup storage.
+        content = b'repair_content_present'
+        id = self.checker.objstorage.add_bytes(content)
+        # Add a content to the mock
+        self.checker.backup_storage.content_add(id, content)
+        # Corrupt and repair it.
+        self.corrupt_content(id)
+        self.assertFalse(self.checker.check_content(id))
+        self.checker.repair_contents([id])
+        self.assertTrue(self.checker.check_content(id))
+
+    @istest
+    def repair_content_missing(self):
+        # Try to repair a content that is NOT in the backup storage.
+        content = b'repair_content_present'
+        id = self.checker.objstorage.add_bytes(content)
+        # Corrupt and repair it.
+        self.corrupt_content(id)
+        self.assertFalse(self.checker.check_content(id))
+        self.checker.repair_contents([id])
+        self.assertFalse(self.checker.check_content(id))