diff --git a/requirements-swh.txt b/requirements-swh.txt
--- a/requirements-swh.txt
+++ b/requirements-swh.txt
@@ -1,4 +1,4 @@
 swh.model >= 0.4.0
 swh.storage >= 0.22.0
 swh.scheduler >= 0.0.39
-swh.loader.core >= 0.17.0
+swh.loader.core >= 0.18.0
diff --git a/requirements.txt b/requirements.txt
--- a/requirements.txt
+++ b/requirements.txt
@@ -9,3 +9,4 @@
 retrying
 sqlitedict
 mercurial
+iso8601
diff --git a/swh/loader/mercurial/cli.py b/swh/loader/mercurial/cli.py
--- a/swh/loader/mercurial/cli.py
+++ b/swh/loader/mercurial/cli.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2018  The Software Heritage developers
+# Copyright (C) 2018-2021  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
@@ -34,6 +34,7 @@
 def main(
     origin_url, hg_directory=None, hg_archive=None, visit_date=None, log_level=None
 ):
+    from swh.storage import get_storage
 
     logging.basicConfig(
         level=(log_level or "DEBUG").upper(),
@@ -52,7 +53,8 @@
 
         kwargs["directory"] = hg_directory
 
-    return HgLoader().load(**kwargs)
+    storage = get_storage(cls="memory")
+    return HgLoader(storage, **kwargs).load()
 
 
 if __name__ == "__main__":
diff --git a/swh/loader/mercurial/from_disk.py b/swh/loader/mercurial/from_disk.py
--- a/swh/loader/mercurial/from_disk.py
+++ b/swh/loader/mercurial/from_disk.py
@@ -1,23 +1,20 @@
-# Copyright (C) 2020  The Software Heritage developers
+# Copyright (C) 2020-2021  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
 
-import os
 from collections import deque
-from datetime import datetime, timezone
+from datetime import datetime
+import os
 from shutil import rmtree
 from tempfile import mkdtemp
-from typing import Any, Deque, Dict, Optional, Tuple, TypeVar, Union
-
-import dateutil
+from typing import Deque, Dict, Optional, Tuple, TypeVar, Union
 
-from swh.core.config import merge_configs
 from swh.loader.core.loader import BaseLoader
 from swh.loader.core.utils import clean_dangling_folders
+from swh.loader.mercurial.utils import parse_visit_date
 from swh.model.from_disk import Content, DentryPerms, Directory
 from swh.model.hashutil import MultiHash, hash_to_bytehex
-from swh.model.model import Content as ModelContent
 from swh.model.model import (
     ObjectType,
     Origin,
@@ -31,6 +28,8 @@
     TargetType,
     TimestampWithTimezone,
 )
+from swh.model.model import Content as ModelContent
+from swh.storage.interface import StorageInterface
 
 from . import hgutil
 from .archive_extract import tmp_extract
@@ -41,38 +40,13 @@
     b"x": DentryPerms.executable_content,
     b"": DentryPerms.content,
 }  # type: Dict[bytes, DentryPerms]
-DEFAULT_CONFIG: Dict[str, Any] = {
-    "temp_directory": "/tmp",
-    "clone_timeout_seconds": 7200,
-    "content_cache_size": 10_000,
-}
+
 TEMPORARY_DIR_PREFIX_PATTERN = "swh.loader.mercurial.from_disk"
 
 
 T = TypeVar("T")
 
 
-def parse_visit_date(visit_date: Optional[Union[datetime, str]]) -> Optional[datetime]:
-    """Convert visit date from Optional[Union[str, datetime]] to Optional[datetime].
-
-    `HgLoaderFromDisk` accepts `str` and `datetime` as visit date
-    while `BaseLoader` only deals with `datetime`.
-    """
-    if visit_date is None:
-        return None
-
-    if isinstance(visit_date, datetime):
-        return visit_date
-
-    if visit_date == "now":
-        return datetime.now(tz=timezone.utc)
-
-    if isinstance(visit_date, str):
-        return dateutil.parser.parse(visit_date)
-
-    return ValueError(f"invalid visit date {visit_date!r}")
-
-
 class HgDirectory(Directory):
     """A more practical directory.
 
@@ -122,11 +96,15 @@
 
     def __init__(
         self,
+        storage: StorageInterface,
         url: str,
         directory: Optional[str] = None,
         logging_class: str = "swh.loader.mercurial.LoaderFromDisk",
-        visit_date: Optional[Union[datetime, str]] = None,
-        config: Optional[Dict[str, Any]] = None,
+        visit_date: Optional[datetime] = None,
+        temp_directory: str = "/tmp",
+        clone_timeout_seconds: int = 7200,
+        content_cache_size: int = 10_000,
+        max_content_size: Optional[int] = None,
     ):
         """Initialize the loader.
 
@@ -137,14 +115,17 @@
             visit_date: visit date of the repository
             config: loader configuration
         """
-        super().__init__(logging_class=logging_class, config=config or {})
+        super().__init__(
+            storage=storage,
+            logging_class=logging_class,
+            max_content_size=max_content_size,
+        )
 
-        self.config = merge_configs(DEFAULT_CONFIG, self.config)
-        self._temp_directory = self.config["temp_directory"]
-        self._clone_timeout = self.config["clone_timeout_seconds"]
+        self._temp_directory = temp_directory
+        self._clone_timeout = clone_timeout_seconds
 
         self.origin_url = url
-        self.visit_date = parse_visit_date(visit_date)
+        self.visit_date = visit_date
         self.directory = directory
 
         self._repo: Optional[hgutil.Repository] = None
@@ -162,7 +143,7 @@
 
         # Cache the content hash across revisions to avoid recalculation.
         self._content_hash_cache: hgutil.LRUCacheDict = hgutil.LRUCacheDict(
-            self.config["content_cache_size"],
+            content_cache_size,
         )
 
     def pre_cleanup(self) -> None:
@@ -182,7 +163,7 @@
             self.log.debug(f"Cleanup up repository {self._repo_directory}")
             rmtree(self._repo_directory)
 
-    def prepare_origin_visit(self, *args, **kwargs) -> None:
+    def prepare_origin_visit(self) -> None:
         """First step executed by the loader to prepare origin and visit
         references. Set/update self.origin, and
         optionally self.origin_url, self.visit_date.
@@ -190,7 +171,7 @@
         """
         self.origin = Origin(url=self.origin_url)
 
-    def prepare(self, *args, **kwargs) -> None:
+    def prepare(self) -> None:
         """Second step executed by the loader to prepare some state needed by
         the loader.
 
@@ -478,19 +459,28 @@
     """Mercurial loader for repository wrapped within tarballs."""
 
     def __init__(
-        self, url: str, visit_date: Optional[datetime] = None, archive_path: str = None
+        self,
+        storage: StorageInterface,
+        url: str,
+        visit_date: Optional[datetime] = None,
+        archive_path: str = None,
+        temp_directory: str = "/tmp",
+        max_content_size: Optional[int] = None,
     ):
         super().__init__(
-            url,
+            storage=storage,
+            url=url,
             visit_date=visit_date,
             logging_class="swh.loader.mercurial.ArchiveLoaderFromDisk",
+            temp_directory=temp_directory,
+            max_content_size=max_content_size,
         )
-        self.temp_dir = None
+        self.archive_extract_temp_dir = None
         self.archive_path = archive_path
 
-    def prepare(self, *args, **kwargs):
+    def prepare(self):
         """Extract the archive instead of cloning."""
-        self._temp_directory = tmp_extract(
+        self.archive_extract_temp_dir = tmp_extract(
             archive=self.archive_path,
             dir=self._temp_directory,
             prefix=TEMPORARY_DIR_PREFIX_PATTERN,
@@ -500,14 +490,8 @@
         )
 
         repo_name = os.listdir(self.temp_dir)[0]
-        self.directory = os.path.join(self.temp_dir, repo_name)
-        super().prepare(*args, **kwargs)
-
-    def cleanup(self) -> None:
-        """Remove the extracted archive instead of the cloned repository."""
-        if self.temp_dir and os.path.exists(self.temp_dir):
-            rmtree(self.temp_dir)
-        super().cleanup()
+        self.directory = os.path.join(self.archive_extract_temp_dir, repo_name)
+        super().prepare()
 
 
 # Allow direct usage of the loader from the command line with
@@ -526,8 +510,14 @@
     @click.option("--hg-directory", help="Path to mercurial repository to load")
     @click.option("--visit-date", default=None, help="Visit date")
     def main(origin_url, hg_directory, visit_date):
+        from swh.storage import get_storage
+
+        storage = get_storage(cls="memory")
         return HgLoaderFromDisk(
-            origin_url, directory=hg_directory, visit_date=visit_date
+            storage,
+            origin_url,
+            directory=hg_directory,
+            visit_date=parse_visit_date(visit_date),
         ).load()
 
     main()
diff --git a/swh/loader/mercurial/loader.py b/swh/loader/mercurial/loader.py
--- a/swh/loader/mercurial/loader.py
+++ b/swh/loader/mercurial/loader.py
@@ -28,11 +28,9 @@
 from typing import Any, Dict, Iterable, List, Optional
 
 import billiard
-from dateutil import parser
 import hglib
 from hglib.error import CommandError
 
-from swh.core.config import merge_configs
 from swh.loader.core.loader import DVCSLoader
 from swh.loader.core.utils import clean_dangling_folders
 from swh.loader.exception import NotFound
@@ -62,6 +60,7 @@
     TimestampWithTimezone,
 )
 from swh.storage.algos.origin import origin_get_latest_visit_status
+from swh.storage.interface import StorageInterface
 
 from . import converters
 from .archive_extract import tmp_extract
@@ -93,16 +92,6 @@
     pass
 
 
-DEFAULT_CONFIG: Dict[str, Any] = {
-    "bundle_filename": "HG20_none_bundle",
-    "reduce_effort": False,
-    "temp_directory": "/tmp",
-    "cache1_size": 800 * 1024 * 1024,
-    "cache2_size": 800 * 1024 * 1024,
-    "clone_timeout_seconds": 7200,
-}
-
-
 class HgBundle20Loader(DVCSLoader):
     """Mercurial loader able to deal with remote or local repository.
 
@@ -112,27 +101,40 @@
 
     def __init__(
         self,
-        url,
-        visit_date=None,
-        directory=None,
+        storage: StorageInterface,
+        url: str,
+        visit_date: Optional[datetime.datetime] = None,
+        directory: Optional[str] = None,
         logging_class="swh.loader.mercurial.Bundle20Loader",
+        bundle_filename: Optional[str] = "HG20_none_bundle",
+        reduce_effort: bool = False,
+        temp_directory: str = "/tmp",
+        cache1_size: int = 800 * 1024 * 1024,
+        cache2_size: int = 800 * 1024 * 1024,
+        clone_timeout_seconds: int = 7200,
+        save_data_path: Optional[str] = None,
+        max_content_size: Optional[int] = None,
     ):
-        super().__init__(logging_class=logging_class)
-        self.config = merge_configs(DEFAULT_CONFIG, self.config)
+        super().__init__(
+            storage=storage,
+            logging_class=logging_class,
+            save_data_path=save_data_path,
+            max_content_size=max_content_size,
+        )
         self.origin_url = url
         self.visit_date = visit_date
         self.directory = directory
-        self.bundle_filename = self.config["bundle_filename"]
-        self.reduce_effort_flag = self.config["reduce_effort"]
+        self.bundle_filename = bundle_filename
+        self.reduce_effort_flag = reduce_effort
         self.empty_repository = None
-        self.temp_directory = self.config["temp_directory"]
-        self.cache1_size = self.config["cache1_size"]
-        self.cache2_size = self.config["cache2_size"]
-        self.clone_timeout = self.config["clone_timeout_seconds"]
+        self.temp_directory = temp_directory
+        self.cache1_size = cache1_size
+        self.cache2_size = cache2_size
+        self.clone_timeout = clone_timeout_seconds
         self.working_directory = None
         self.bundle_path = None
-        self.heads = {}
-        self.releases = {}
+        self.heads: Dict[bytes, Any] = {}
+        self.releases: Dict[bytes, Any] = {}
         self.last_snapshot_id: Optional[bytes] = None
 
     def pre_cleanup(self):
@@ -179,12 +181,8 @@
 
         return b
 
-    def prepare_origin_visit(self, *args, **kwargs) -> None:
+    def prepare_origin_visit(self) -> None:
         self.origin = Origin(url=self.origin_url)
-        visit_date = self.visit_date
-        if isinstance(visit_date, str):  # visit_date can be string or datetime
-            visit_date = parser.parse(visit_date)
-        self.visit_date = visit_date
         visit_status = origin_get_latest_visit_status(
             self.storage, self.origin_url, require_snapshot=True
         )
@@ -231,7 +229,7 @@
 
         return result
 
-    def prepare(self, *args, **kwargs):
+    def prepare(self):
         """Prepare the necessary steps to load an actual remote or local
            repository.
 
@@ -638,17 +636,28 @@
 
     """
 
-    def __init__(self, url, visit_date=None, archive_path=None):
+    def __init__(
+        self,
+        storage: StorageInterface,
+        url: str,
+        visit_date: Optional[datetime.datetime] = None,
+        archive_path=None,
+        temp_directory: str = "/tmp",
+        max_content_size: Optional[int] = None,
+    ):
         super().__init__(
-            url,
+            storage=storage,
+            url=url,
             visit_date=visit_date,
             logging_class="swh.loader.mercurial.HgArchiveBundle20Loader",
+            temp_directory=temp_directory,
+            max_content_size=max_content_size,
         )
-        self.temp_dir = None
+        self.archive_extract_temp_dir = None
         self.archive_path = archive_path
 
-    def prepare(self, *args, **kwargs):
-        self.temp_dir = tmp_extract(
+    def prepare(self):
+        self.archive_extract_temp_dir = tmp_extract(
             archive=self.archive_path,
             dir=self.temp_directory,
             prefix=TEMPORARY_DIR_PREFIX_PATTERN,
@@ -657,11 +666,6 @@
             source=self.origin_url,
         )
 
-        repo_name = os.listdir(self.temp_dir)[0]
-        self.directory = os.path.join(self.temp_dir, repo_name)
-        super().prepare(*args, **kwargs)
-
-    def cleanup(self):
-        if self.temp_dir and os.path.exists(self.temp_dir):
-            rmtree(self.temp_dir)
-        super().cleanup()
+        repo_name = os.listdir(self.archive_extract_temp_dir)[0]
+        self.directory = os.path.join(self.archive_extract_temp_dir, repo_name)
+        super().prepare()
diff --git a/swh/loader/mercurial/tasks.py b/swh/loader/mercurial/tasks.py
--- a/swh/loader/mercurial/tasks.py
+++ b/swh/loader/mercurial/tasks.py
@@ -1,10 +1,12 @@
-# Copyright (C) 2017-2019  The Software Heritage developers
+# Copyright (C) 2017-2021  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
 
 from celery import shared_task
 
+from swh.loader.mercurial.utils import parse_visit_date
+
 from .loader import HgArchiveBundle20Loader, HgBundle20Loader
 
 
@@ -14,10 +16,13 @@
 
     Import a mercurial tarball into swh.
 
-    Args: see :func:`DepositLoader.load`.
+    Args: see :func:`HgBundle20Loader.load`.
 
     """
-    loader = HgBundle20Loader(url, directory=directory, visit_date=visit_date)
+
+    loader = HgBundle20Loader.from_configfile(
+        url=url, directory=directory, visit_date=parse_visit_date(visit_date)
+    )
     return loader.load()
 
 
@@ -25,9 +30,9 @@
 def load_hg_from_archive(*, url, archive_path=None, visit_date=None):
     """Import a mercurial tarball into swh.
 
-    Args: see :func:`DepositLoader.load`.
+    Args: see :func:`HgArchiveBundle20Loader.load`.
     """
-    loader = HgArchiveBundle20Loader(
-        url, archive_path=archive_path, visit_date=visit_date
+    loader = HgArchiveBundle20Loader.from_configfile(
+        url=url, archive_path=archive_path, visit_date=parse_visit_date(visit_date)
     )
     return loader.load()
diff --git a/swh/loader/mercurial/tasks_from_disk.py b/swh/loader/mercurial/tasks_from_disk.py
--- a/swh/loader/mercurial/tasks_from_disk.py
+++ b/swh/loader/mercurial/tasks_from_disk.py
@@ -1,10 +1,12 @@
-# Copyright (C) 2020  The Software Heritage developers
+# Copyright (C) 2020-2021  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
 
 from celery import shared_task
 
+from swh.loader.mercurial.utils import parse_visit_date
+
 from .from_disk import HgArchiveLoaderFromDisk, HgLoaderFromDisk
 
 
@@ -17,7 +19,9 @@
     Args: see :func:`DepositLoader.load`.
 
     """
-    loader = HgLoaderFromDisk(url, directory=directory, visit_date=visit_date)
+    loader = HgLoaderFromDisk.from_configfile(
+        url=url, directory=directory, visit_date=parse_visit_date(visit_date)
+    )
     return loader.load()
 
 
@@ -27,7 +31,7 @@
 
     Args: see :func:`DepositLoader.load`.
     """
-    loader = HgArchiveLoaderFromDisk(
-        url, archive_path=archive_path, visit_date=visit_date
+    loader = HgArchiveLoaderFromDisk.from_configfile(
+        url=url, archive_path=archive_path, visit_date=parse_visit_date(visit_date)
     )
     return loader.load()
diff --git a/swh/loader/mercurial/tests/conftest.py b/swh/loader/mercurial/tests/conftest.py
--- a/swh/loader/mercurial/tests/conftest.py
+++ b/swh/loader/mercurial/tests/conftest.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2019-2020  The Software Heritage developers
+# Copyright (C) 2019-2021  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
@@ -9,33 +9,31 @@
 
 
 @pytest.fixture
-def swh_loader_config(swh_storage_backend_config, tmp_path) -> Dict[str, Any]:
-    swh_storage_backend_config["journal_writer"] = {}
+def swh_storage_backend_config(swh_storage_backend_config):
+    """Basic pg storage configuration with no journal collaborator
+    (to avoid pulling optional dependency on clients of this fixture)
+
+    """
     return {
+        "cls": "filter",
         "storage": {
-            "cls": "pipeline",
-            "steps": [
-                {"cls": "filter"},
-                {
-                    "cls": "buffer",
-                    "min_batch_size": {
-                        "content": 10000,
-                        "content_bytes": 1073741824,
-                        "directory": 2500,
-                        "revision": 10,
-                        "release": 100,
-                    },
-                },
-                swh_storage_backend_config,
-            ],
+            "cls": "buffer",
+            "min_batch_size": {
+                "content": 10,
+                "content_bytes": 100 * 1024 * 1024,
+                "directory": 10,
+                "revision": 10,
+                "release": 10,
+            },
+            "storage": swh_storage_backend_config,
         },
-        "bundle_filename": "HG20_none_bundle",
-        "cache1_size": 838860800,
-        "cache2_size": 838860800,
-        "clone_timeout_seconds": 2 * 3600,
-        "reduce_effort": False,
-        "save_data": False,
-        "save_data_path": "",
+    }
+
+
+@pytest.fixture
+def swh_loader_config(swh_storage_backend_config, tmp_path) -> Dict[str, Any]:
+    return {
+        "storage": swh_storage_backend_config,
         "max_content_size": 104857600,
         "temp_directory": str(tmp_path),
     }
diff --git a/swh/loader/mercurial/tests/test_from_disk.py b/swh/loader/mercurial/tests/test_from_disk.py
--- a/swh/loader/mercurial/tests/test_from_disk.py
+++ b/swh/loader/mercurial/tests/test_from_disk.py
@@ -1,12 +1,13 @@
-# Copyright (C) 2020  The Software Heritage developers
+# Copyright (C) 2020-2021  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
 
-import os
 from datetime import datetime
 from hashlib import sha1
+import os
 
+from swh.loader.mercurial.utils import parse_visit_date
 from swh.loader.tests import (
     assert_last_visit_matches,
     check_snapshot,
@@ -21,6 +22,9 @@
 from ..from_disk import HgDirectory, HgLoaderFromDisk
 from .loader_checker import ExpectedSwhids, LoaderChecker
 
+VISIT_DATE = parse_visit_date("2016-05-03 15:16:32+00")
+assert VISIT_DATE is not None
+
 
 def random_content() -> Content:
     """Create minimal content object."""
@@ -73,14 +77,15 @@
 #
 # With more work it should event be possible to know which part
 # of an object is faulty.
-def test_examples(swh_config, datadir, tmp_path):
+def test_examples(swh_storage, datadir, tmp_path):
     for archive_name in ("hello", "transplant", "the-sandbox", "example"):
         archive_path = os.path.join(datadir, f"{archive_name}.tgz")
         json_path = os.path.join(datadir, f"{archive_name}.json")
         repo_url = prepare_repository_from_archive(archive_path, archive_name, tmp_path)
 
         LoaderChecker(
-            loader=HgLoaderFromDisk(repo_url), expected=ExpectedSwhids.load(json_path),
+            loader=HgLoaderFromDisk(swh_storage, repo_url),
+            expected=ExpectedSwhids.load(json_path),
         ).check()
 
 
@@ -88,13 +93,13 @@
 # to ensure compatibility of `HgLoaderFromDisk`.
 # Hashes as been produced by copy pasting the result of the implementation
 # to prevent regressions.
-def test_loader_hg_new_visit_no_release(swh_config, datadir, tmp_path):
+def test_loader_hg_new_visit_no_release(swh_storage, datadir, tmp_path):
     """Eventful visit should yield 1 snapshot"""
     archive_name = "the-sandbox"
     archive_path = os.path.join(datadir, f"{archive_name}.tgz")
     repo_url = prepare_repository_from_archive(archive_path, archive_name, tmp_path)
 
-    loader = HgLoaderFromDisk(url=repo_url)
+    loader = HgLoaderFromDisk(swh_storage, url=repo_url)
 
     assert loader.load() == {"status": "eventful"}
 
@@ -141,14 +146,14 @@
 # to ensure compatibility of `HgLoaderFromDisk`.
 # Hashes as been produced by copy pasting the result of the implementation
 # to prevent regressions.
-def test_loader_hg_new_visit_with_release(swh_config, datadir, tmp_path):
+def test_loader_hg_new_visit_with_release(swh_storage, datadir, tmp_path):
     """Eventful visit with release should yield 1 snapshot"""
 
     archive_name = "hello"
     archive_path = os.path.join(datadir, f"{archive_name}.tgz")
     repo_url = prepare_repository_from_archive(archive_path, archive_name, tmp_path)
 
-    loader = HgLoaderFromDisk(url=repo_url, visit_date="2016-05-03 15:16:32+00")
+    loader = HgLoaderFromDisk(swh_storage, url=repo_url, visit_date=VISIT_DATE,)
 
     actual_load_status = loader.load()
     assert actual_load_status == {"status": "eventful"}
@@ -200,7 +205,7 @@
 # to ensure compatibility of `HgLoaderFromDisk`.
 # Hashes as been produced by copy pasting the result of the implementation
 # to prevent regressions.
-def test_visit_repository_with_transplant_operations(swh_config, datadir, tmp_path):
+def test_visit_repository_with_transplant_operations(swh_storage, datadir, tmp_path):
     """Visit a mercurial repository visit transplant operations within should yield a
     snapshot as well.
 
@@ -210,7 +215,7 @@
     archive_path = os.path.join(datadir, f"{archive_name}.tgz")
     repo_url = prepare_repository_from_archive(archive_path, archive_name, tmp_path)
 
-    loader = HgLoaderFromDisk(url=repo_url, visit_date="2016-05-03 15:16:32+00")
+    loader = HgLoaderFromDisk(swh_storage, url=repo_url, visit_date=VISIT_DATE,)
 
     # load hg repository
     actual_load_status = loader.load()
diff --git a/swh/loader/mercurial/tests/test_loader.py b/swh/loader/mercurial/tests/test_loader.py
--- a/swh/loader/mercurial/tests/test_loader.py
+++ b/swh/loader/mercurial/tests/test_loader.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2018-2020  The Software Heritage developers
+# Copyright (C) 2018-2021  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
@@ -12,6 +12,7 @@
 from hglib.error import CommandError
 import pytest
 
+from swh.loader.mercurial.utils import parse_visit_date
 from swh.loader.tests import (
     assert_last_visit_matches,
     check_snapshot,
@@ -24,14 +25,17 @@
 
 from ..loader import CloneTimeoutError, HgArchiveBundle20Loader, HgBundle20Loader
 
+VISIT_DATE = parse_visit_date("2016-05-03 15:16:32+00")
+assert VISIT_DATE is not None
 
-def test_loader_hg_new_visit_no_release(swh_config, datadir, tmp_path):
+
+def test_loader_hg_new_visit_no_release(swh_storage, datadir, tmp_path):
     """Eventful visit should yield 1 snapshot"""
     archive_name = "the-sandbox"
     archive_path = os.path.join(datadir, f"{archive_name}.tgz")
     repo_url = prepare_repository_from_archive(archive_path, archive_name, tmp_path)
 
-    loader = HgBundle20Loader(repo_url)
+    loader = HgBundle20Loader(swh_storage, repo_url)
 
     assert loader.load() == {"status": "eventful"}
 
@@ -53,15 +57,15 @@
     )
 
     assert_last_visit_matches(
-        loader.storage,
+        swh_storage,
         repo_url,
         status="full",
         type="hg",
         snapshot=expected_snapshot.id,
     )
-    check_snapshot(expected_snapshot, loader.storage)
+    check_snapshot(expected_snapshot, swh_storage)
 
-    stats = get_stats(loader.storage)
+    stats = get_stats(swh_storage)
     assert stats == {
         "content": 2,
         "directory": 3,
@@ -75,9 +79,7 @@
 
     # Ensure archive loader yields the same snapshot
     loader2 = HgArchiveBundle20Loader(
-        url=archive_path,
-        archive_path=archive_path,
-        visit_date="2016-05-03 15:16:32+00",
+        swh_storage, url=archive_path, archive_path=archive_path, visit_date=VISIT_DATE,
     )
 
     actual_load_status = loader2.load()
@@ -99,19 +101,19 @@
     )
 
 
-def test_loader_hg_new_visit_with_release(swh_config, datadir, tmp_path):
+def test_loader_hg_new_visit_with_release(swh_storage, datadir, tmp_path):
     """Eventful visit with release should yield 1 snapshot"""
     archive_name = "hello"
     archive_path = os.path.join(datadir, f"{archive_name}.tgz")
     repo_url = prepare_repository_from_archive(archive_path, archive_name, tmp_path)
 
-    loader = HgBundle20Loader(url=repo_url, visit_date="2016-05-03 15:16:32+00",)
+    loader = HgBundle20Loader(swh_storage, url=repo_url, visit_date=VISIT_DATE,)
 
     actual_load_status = loader.load()
     assert actual_load_status == {"status": "eventful"}
 
     # then
-    stats = get_stats(loader.storage)
+    stats = get_stats(swh_storage)
     assert stats == {
         "content": 3,
         "directory": 3,
@@ -125,11 +127,11 @@
 
     # cf. test_loader.org for explaining from where those hashes
     tip_release = hash_to_bytes("515c4d72e089404356d0f4b39d60f948b8999140")
-    release = loader.storage.release_get([tip_release])[0]
+    release = swh_storage.release_get([tip_release])[0]
     assert release is not None
 
     tip_revision_default = hash_to_bytes("c3dbe4fbeaaa98dd961834e4007edb3efb0e2a27")
-    revision = loader.storage.revision_get([tip_revision_default])[0]
+    revision = swh_storage.revision_get([tip_revision_default])[0]
     assert revision is not None
 
     expected_snapshot = Snapshot(
@@ -143,9 +145,9 @@
         },
     )
 
-    check_snapshot(expected_snapshot, loader.storage)
+    check_snapshot(expected_snapshot, swh_storage)
     assert_last_visit_matches(
-        loader.storage,
+        swh_storage,
         repo_url,
         type=RevisionType.MERCURIAL.value,
         status="full",
@@ -154,9 +156,7 @@
 
     # Ensure archive loader yields the same snapshot
     loader2 = HgArchiveBundle20Loader(
-        url=archive_path,
-        archive_path=archive_path,
-        visit_date="2016-05-03 15:16:32+00",
+        swh_storage, url=archive_path, archive_path=archive_path, visit_date=VISIT_DATE,
     )
 
     actual_load_status = loader2.load()
@@ -178,7 +178,7 @@
     )
 
 
-def test_visit_with_archive_decompression_failure(swh_config, mocker, datadir):
+def test_visit_with_archive_decompression_failure(swh_storage, mocker, datadir):
     """Failure to decompress should fail early, no data is ingested"""
     mock_patoo = mocker.patch("swh.loader.mercurial.archive_extract.patoolib")
     mock_patoo.side_effect = ValueError
@@ -187,13 +187,13 @@
     archive_path = os.path.join(datadir, f"{archive_name}.tgz")
 
     loader = HgArchiveBundle20Loader(
-        url=archive_path, visit_date="2016-05-03 15:16:32+00",
+        swh_storage, url=archive_path, visit_date=VISIT_DATE,
     )
 
     actual_load_status = loader.load()
     assert actual_load_status == {"status": "failed"}
 
-    stats = get_stats(loader.storage)
+    stats = get_stats(swh_storage)
     assert stats == {
         "content": 0,
         "directory": 0,
@@ -206,11 +206,11 @@
     }
     # That visit yields the same snapshot
     assert_last_visit_matches(
-        loader.storage, archive_path, status="failed", type="hg", snapshot=None
+        swh_storage, archive_path, status="failed", type="hg", snapshot=None
     )
 
 
-def test_visit_error_with_snapshot_partial(swh_config, datadir, tmp_path, mocker):
+def test_visit_error_with_snapshot_partial(swh_storage, datadir, tmp_path, mocker):
     """Incomplete ingestion leads to a 'partial' ingestion status"""
     mock = mocker.patch("swh.loader.mercurial.loader.HgBundle20Loader.store_metadata")
     mock.side_effect = ValueError
@@ -219,12 +219,12 @@
     archive_path = os.path.join(datadir, f"{archive_name}.tgz")
     repo_url = prepare_repository_from_archive(archive_path, archive_name, tmp_path)
 
-    loader = HgBundle20Loader(repo_url)
+    loader = HgBundle20Loader(swh_storage, repo_url)
 
     assert loader.load() == {"status": "failed"}
 
     assert_last_visit_matches(
-        loader.storage,
+        swh_storage,
         repo_url,
         status="partial",
         type="hg",
@@ -242,7 +242,7 @@
     ],
 )
 def test_visit_error_with_status_not_found(
-    swh_config, datadir, tmp_path, mocker, error_msg
+    swh_storage, datadir, tmp_path, mocker, error_msg
 ):
     """Not reaching the repo leads to a 'not_found' ingestion status"""
     mock = mocker.patch("hglib.clone")
@@ -252,16 +252,16 @@
     archive_path = os.path.join(datadir, f"{archive_name}.tgz")
     repo_url = prepare_repository_from_archive(archive_path, archive_name, tmp_path)
 
-    loader = HgBundle20Loader(repo_url)
+    loader = HgBundle20Loader(swh_storage, repo_url)
 
     assert loader.load() == {"status": "uneventful"}
 
     assert_last_visit_matches(
-        loader.storage, repo_url, status="not_found", type="hg", snapshot=None,
+        swh_storage, repo_url, status="not_found", type="hg", snapshot=None,
     )
 
 
-def test_visit_error_with_clone_error(swh_config, datadir, tmp_path, mocker):
+def test_visit_error_with_clone_error(swh_storage, datadir, tmp_path, mocker):
     """Testing failures other than 'not_found'"""
 
     mock = mocker.patch("hglib.clone")
@@ -271,16 +271,16 @@
     archive_path = os.path.join(datadir, f"{archive_name}.tgz")
     repo_url = prepare_repository_from_archive(archive_path, archive_name, tmp_path)
 
-    loader = HgBundle20Loader(repo_url)
+    loader = HgBundle20Loader(swh_storage, repo_url)
 
     assert loader.load() == {"status": "failed"}
 
     assert_last_visit_matches(
-        loader.storage, repo_url, status="failed", type="hg", snapshot=None,
+        swh_storage, repo_url, status="failed", type="hg", snapshot=None,
     )
 
 
-def test_visit_repository_with_transplant_operations(swh_config, datadir, tmp_path):
+def test_visit_repository_with_transplant_operations(swh_storage, datadir, tmp_path):
     """Visit a mercurial repository visit transplant operations within should yield a
     snapshot as well.
 
@@ -289,7 +289,7 @@
     archive_name = "transplant"
     archive_path = os.path.join(datadir, f"{archive_name}.tgz")
     repo_url = prepare_repository_from_archive(archive_path, archive_name, tmp_path)
-    loader = HgBundle20Loader(url=repo_url, visit_date="2019-05-23 12:06:00+00",)
+    loader = HgBundle20Loader(swh_storage, url=repo_url, visit_date=VISIT_DATE,)
 
     # load hg repository
     actual_load_status = loader.load()
@@ -297,11 +297,11 @@
 
     # collect swh revisions
     assert_last_visit_matches(
-        loader.storage, repo_url, type=RevisionType.MERCURIAL.value, status="full"
+        swh_storage, repo_url, type=RevisionType.MERCURIAL.value, status="full"
     )
 
     revisions = []
-    snapshot = snapshot_get_latest(loader.storage, repo_url)
+    snapshot = snapshot_get_latest(swh_storage, repo_url)
     for branch in snapshot.branches.values():
         if branch.target_type.value != "revision":
             continue
@@ -310,7 +310,7 @@
     # extract original changesets info and the transplant sources
     hg_changesets = set()
     transplant_sources = set()
-    for rev in loader.storage.revision_log(revisions):
+    for rev in swh_storage.revision_log(revisions):
         hg_changesets.add(rev["metadata"]["node"])
         for k, v in rev["extra_headers"]:
             if k == b"transplant_source":
diff --git a/swh/loader/mercurial/utils.py b/swh/loader/mercurial/utils.py
new file mode 100644
--- /dev/null
+++ b/swh/loader/mercurial/utils.py
@@ -0,0 +1,29 @@
+# Copyright (C) 2020-2021  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
+
+from datetime import datetime, timezone
+from typing import Optional, Union
+
+import dateutil
+
+
+def parse_visit_date(visit_date: Optional[Union[datetime, str]]) -> Optional[datetime]:
+    """Convert visit date from either None, a string or a datetime to either None or
+       datetime.
+
+    """
+    if visit_date is None:
+        return None
+
+    if isinstance(visit_date, datetime):
+        return visit_date
+
+    if visit_date == "now":
+        return datetime.now(tz=timezone.utc)
+
+    if isinstance(visit_date, str):
+        return dateutil.parser.parse(visit_date)
+
+    return ValueError(f"invalid visit date {visit_date!r}")