tests: Add some initial tests for tuf.repository

Signed-off-by: Jussi Kukkonen <jkukkonen@google.com>

tests/test_repository.py

@@ -0,0 +1,182 @@
+# Copyright 2021-2022 python-tuf contributors
+# SPDX-License-Identifier: MIT OR Apache-2.0
+
+"""Tests for tuf.repository module"""
+
+import copy
+import logging
+import sys
+import unittest
+from collections import defaultdict
+from datetime import datetime, timedelta, timezone
+from typing import Dict, List
+
+from securesystemslib.signer import CryptoSigner, Signer
+
+from tests import utils
+from tuf.api.metadata import (
+    TOP_LEVEL_ROLE_NAMES,
+    Metadata,
+    MetaFile,
+    Root,
+    Snapshot,
+    TargetFile,
+    Targets,
+    Timestamp,
+)
+from tuf.repository import Repository
+
+logger = logging.getLogger(__name__)
+
+_signed_init = {
+    Root.type: Root,
+    Snapshot.type: Snapshot,
+    Targets.type: Targets,
+    Timestamp.type: Timestamp,
+}
+
+
+class TestingRepository(Repository):
+    """Very simple in-memory repository implementation
+
+    This repository keeps the metadata for all versions of all roles in memory.
+    It also keeps all target content in memory.
+
+    Mostly copied from examples/repository.
+
+    Attributes:
+        role_cache: Every historical metadata version of every role in this
+            repository. Keys are role names and values are lists of Metadata
+        signer_cache: All signers available to the repository. Keys are role
+            names, values are lists of signers
+    """
+
+    expiry_period = timedelta(days=1)
+
+    def __init__(self) -> None:
+        # all versions of all metadata
+        self.role_cache: Dict[str, List[Metadata]] = defaultdict(list)
+        # all current keys
+        self.signer_cache: Dict[str, List[Signer]] = defaultdict(list)
+        # version cache for snapshot and all targets, updated in close().
+        # The 'defaultdict(lambda: ...)' trick allows close() to easily modify
+        # the version without always creating a new MetaFile
+        self._snapshot_info = MetaFile(1)
+        self._targets_infos: Dict[str, MetaFile] = defaultdict(
+            lambda: MetaFile(1)
+        )
+
+        # setup a basic repository, generate signing key per top-level role
+        with self.edit_root() as root:
+            for role in ["root", "timestamp", "snapshot", "targets"]:
+                signer = CryptoSigner.generate_ecdsa()
+                self.signer_cache[role].append(signer)
+                root.add_key(signer.public_key, role)
+
+        for role in ["timestamp", "snapshot", "targets"]:
+            with self.edit(role):
+                pass
+
+    @property
+    def targets_infos(self) -> Dict[str, MetaFile]:
+        return self._targets_infos
+
+    @property
+    def snapshot_info(self) -> MetaFile:
+        return self._snapshot_info
+
+    def open(self, role: str) -> Metadata:
+        """Return current Metadata for role from 'storage'
+        (or create a new one)
+        """
+
+        if role not in self.role_cache:
+            signed_init = _signed_init.get(role, Targets)
+            md = Metadata(signed_init())
+
+            # this makes version bumping in close() simpler
+            md.signed.version = 0
+            return md
+
+        # return a _copy_ of latest metadata from storage
+        return copy.deepcopy(self.role_cache[role][-1])
+
+    def close(self, role: str, md: Metadata) -> None:
+        """Store a version of metadata. Handle version bumps, expiry, signing"""
+        md.signed.version += 1
+        md.signed.expires = datetime.now(timezone.utc) + self.expiry_period
+
+        md.signatures.clear()
+        for signer in self.signer_cache[role]:
+            md.sign(signer, append=True)
+
+        # store new metadata version, update version caches
+        self.role_cache[role].append(md)
+        if role == "snapshot":
+            self._snapshot_info.version = md.signed.version
+        elif role not in ["root", "timestamp"]:
+            self._targets_infos[f"{role}.json"].version = md.signed.version
+
+
+class TestRepository(unittest.TestCase):
+    """Tests for tuf.repository module."""
+
+    def setUp(self) -> None:
+        self.repo = TestingRepository()
+
+    def test_initial_repo_setup(self) -> None:
+        # check that we have metadata for top level roles
+        self.assertEqual(4, len(self.repo.role_cache))
+        for role in TOP_LEVEL_ROLE_NAMES:
+            # There should be a single version for each role
+            role_versions = self.repo.role_cache[role]
+            self.assertEqual(1, len(role_versions))
+            self.assertEqual(1, role_versions[-1].signed.version)
+
+    def test_do_snapshot(self) -> None:
+        # Expect no-op because targets have not changed and snapshot is still valid
+        created, _ = self.repo.do_snapshot()
+
+        self.assertFalse(created)
+        snapshot_versions = self.repo.role_cache["snapshot"]
+        self.assertEqual(1, len(snapshot_versions))
+        self.assertEqual(1, snapshot_versions[-1].signed.version)
+
+    def test_do_snapshot_after_targets_change(self) -> None:
+        # do a targets change, expect do_snapshot to create a new snapshot
+        with self.repo.edit_targets() as targets:
+            targets.targets["path"] = TargetFile.from_data("path", b"data")
+
+        created, _ = self.repo.do_snapshot()
+
+        self.assertTrue(created)
+        snapshot_versions = self.repo.role_cache["snapshot"]
+        self.assertEqual(2, len(snapshot_versions))
+        self.assertEqual(2, snapshot_versions[-1].signed.version)
+
+    @unittest.expectedFailure  # Issue 2438
+    def test_do_snapshot_after_snapshot_key_change(self) -> None:
+        # change snapshot signing keys
+        with self.repo.edit_root() as root:
+            # remove key
+            keyid = root.roles["snapshot"].keyids[0]
+            root.revoke_key(keyid, "snapshot")
+            self.repo.signer_cache["snapshot"].clear()
+
+            # add new key
+            signer = CryptoSigner.generate_ecdsa()
+            self.repo.signer_cache["snapshot"].append(signer)
+            root.add_key(signer.public_key, "snapshot")
+
+        # snapshot is no longer signed correctly, expect do_snapshot to create a new snapshot
+        created, _ = self.repo.do_snapshot()
+
+        self.assertTrue(created)
+        snapshot_versions = self.repo.role_cache["snapshot"]
+        self.assertEqual(2, len(snapshot_versions))
+        self.assertEqual(2, snapshot_versions[-1].signed.version)
+
+
+if __name__ == "__main__":
+    utils.configure_test_logging(sys.argv)
+    unittest.main()