diff --git a/.gitignore b/.gitignore
--- a/.gitignore
+++ b/.gitignore
@@ -9,3 +9,4 @@
 *.egg-info
 version.txt
 .vscode/
+.hypothesis/
diff --git a/requirements-test.txt b/requirements-test.txt
--- a/requirements-test.txt
+++ b/requirements-test.txt
@@ -1 +1,2 @@
+hypothesis
 nose
diff --git a/swh/storage/algos/snapshot.py b/swh/storage/algos/snapshot.py
new file mode 100644
--- /dev/null
+++ b/swh/storage/algos/snapshot.py
@@ -0,0 +1,31 @@
+# Copyright (C) 2018  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
+
+
+def snapshot_get_all_branches(storage, snapshot_id):
+    """Get all the branches for a given snapshot
+
+    Args:
+        storage (swh.storage.storage.Storage): the storage instance
+        snapshot_id (bytes): the snapshot's identifier
+    Returns:
+        dict: a dict with two keys:
+            * **id**: identifier of the snapshot
+            * **branches**: a dict of branches contained in the snapshot
+              whose keys are the branches' names.
+    """
+    ret = storage.snapshot_get(snapshot_id)
+
+    if not ret:
+        return
+
+    next_branch = ret.pop('next_branch', None)
+    while next_branch:
+        data = storage.snapshot_get_branches(snapshot_id,
+                                             branches_from=next_branch)
+        ret['branches'].update(data['branches'])
+        next_branch = data.get('next_branch')
+
+    return ret
diff --git a/swh/storage/tests/algos/test_snapshot.py b/swh/storage/tests/algos/test_snapshot.py
new file mode 100644
--- /dev/null
+++ b/swh/storage/tests/algos/test_snapshot.py
@@ -0,0 +1,125 @@
+# Copyright (C) 2018  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 unittest
+
+from hypothesis import given, settings
+from hypothesis.strategies import (binary, composite, datetimes, dictionaries,
+                                   from_regex, none, one_of, sampled_from)
+
+from swh.model.identifiers import snapshot_identifier, identifier_to_bytes
+from swh.storage.tests.storage_testing import StorageTestFixture
+
+from swh.storage.algos.snapshot import snapshot_get_all_branches
+
+
+def branch_names():
+    return binary(min_size=5, max_size=10)
+
+
+@composite
+def branch_targets_object(draw):
+    return {
+        'target': draw(binary(min_size=20, max_size=20)),
+        'target_type': draw(
+            sampled_from([
+                'content', 'directory', 'revision', 'release', 'snapshot',
+            ])
+        ),
+    }
+
+
+@composite
+def branch_targets_alias(draw):
+    return {
+        'target': draw(branch_names()),
+        'target_type': 'alias',
+    }
+
+
+def branch_targets(*, only_objects=False):
+    if only_objects:
+        return branch_targets_object()
+    else:
+        return one_of(none(), branch_targets_alias(), branch_targets_object())
+
+
+@composite
+def snapshots(draw, *, min_size=0, max_size=100, only_objects=False):
+    branches = draw(dictionaries(
+        keys=branch_names(),
+        values=branch_targets(only_objects=only_objects),
+        min_size=min_size,
+        max_size=max_size,
+    ))
+
+    if not only_objects:
+        # Make sure aliases point to actual branches
+        unresolved_aliases = {
+            target['target']
+            for target in branches.values()
+            if (target
+                and target['target_type'] == 'alias'
+                and target['target'] not in branches)
+         }
+
+        for alias in unresolved_aliases:
+            branches[alias] = draw(branch_targets(only_objects=True))
+
+    ret = {
+        'branches': branches,
+    }
+    ret['id'] = identifier_to_bytes(snapshot_identifier(ret))
+    return ret
+
+
+@composite
+def urls(draw):
+    protocol = draw(sampled_from(['git', 'http', 'https', 'deb']))
+    domain = draw(from_regex(r'\A([a-z]([a-z0-9-]*)\.){1,3}[a-z0-9]+\Z'))
+
+    return '%s://%s' % (protocol, domain)
+
+
+@composite
+def origins(draw):
+    return {
+        'type': draw(sampled_from(['git', 'hg', 'svn', 'pypi', 'deb'])),
+        'url': draw(urls()),
+    }
+
+
+class TestSnapshotAllBranches(StorageTestFixture, unittest.TestCase):
+    @given(origins(), datetimes(), snapshots(min_size=0, max_size=10,
+                                             only_objects=False))
+    def test_snapshot_small(self, origin, ts, snapshot):
+        origin_id = self.storage.origin_add_one(origin)
+        visit = self.storage.origin_visit_add(origin_id, ts)
+        self.storage.snapshot_add(origin_id, visit['visit'], snapshot)
+
+        returned_snapshot = snapshot_get_all_branches(self.storage,
+                                                      snapshot['id'])
+        self.assertEquals(snapshot, returned_snapshot)
+
+    @settings(max_examples=5, deadline=1000)
+    @given(origins(), datetimes(),
+           branch_names(), branch_targets(only_objects=True))
+    def test_snapshot_large(self, origin, ts, branch_name, branch_target):
+        origin_id = self.storage.origin_add_one(origin)
+        visit = self.storage.origin_visit_add(origin_id, ts)
+
+        snapshot = {
+            'branches': {
+                b'%s%05d' % (branch_name, i): branch_target
+                for i in range(10000)
+            }
+        }
+        snapshot['id'] = identifier_to_bytes(snapshot_identifier(snapshot))
+
+        self.storage.snapshot_add(origin_id, visit['visit'], snapshot)
+
+        returned_snapshot = snapshot_get_all_branches(self.storage,
+                                                      snapshot['id'])
+        self.assertEquals(snapshot, returned_snapshot)