Improve test_consistent_snapshot

- Check for the exact call lists in asserts
- Small docstring improvements
- Minor issues after review

Signed-off-by: Teodora Sechkova <tsechkova@vmware.com>

tests/test_updater_consistent_snapshot.py

@@ -3,7 +3,7 @@
 # Copyright 2021, New York University and the TUF contributors
 # SPDX-License-Identifier: MIT OR Apache-2.0
 
-"""Test ngclient Updater consistent snapshot"""
+"""Test ngclient Updater toggling consistent snapshot"""
 
 import os
 import sys
@@ -23,8 +23,9 @@
 
 
 class TestConsistentSnapshot(unittest.TestCase):
-    """Test different combinations of consistent_snapshot and
-    prefix_targets_with_hash"""
+    """Test different combinations of 'consistent_snapshot' and
+    'prefix_targets_with_hash' and verify that the correct URLs
+    are formed for each combination"""
 
     def setUp(self) -> None:
         self.temp_dir = tempfile.TemporaryDirectory()
@@ -118,11 +119,11 @@ def test_top_level_roles_update(self, test_case_data: Dict[str, Any]):
 
         with patch.object(
             sim, "_fetch_metadata", wraps=sim._fetch_metadata
-        ) as wrapped_fetch_metadata:
+        ) as wrapped_fetch:
             updater.refresh()
 
             # metadata files are fetched with the expected version (or None)
-            wrapped_fetch_metadata.assert_has_calls(expected_calls)
+            self.assertListEqual(wrapped_fetch.call_args_list, expected_calls)
             # metadata files are always persisted without a version prefix
             self._assert_metadata_files_exist(TOP_LEVEL_ROLE_NAMES)
 
@@ -160,11 +161,11 @@ def test_delegated_roles_update(self, test_case_data: Dict[str, Any]):
 
         with patch.object(
             sim, "_fetch_metadata", wraps=sim._fetch_metadata
-        ) as wrapped_fetch_metadata:
+        ) as wrapped_fetch:
             # trigger updater to fetch the delegated metadata
             updater.get_targetinfo("anything")
             # metadata files are fetched with the expected version (or None)
-            wrapped_fetch_metadata.assert_has_calls(expected_calls)
+            self.assertListEqual(wrapped_fetch.call_args_list, expected_calls)
             # metadata files are always persisted without a version prefix
             self._assert_metadata_files_exist(rolenames)
 
@@ -181,7 +182,7 @@ def test_delegated_roles_update(self, test_case_data: Dict[str, Any]):
             "prefix_targets": False,
             "hash_algo": None,
         },
-        "consistent_snaphot_enabled with prefixed targets": {
+        "consistent_snaphot enabled with prefixed targets": {
             "consistent_snapshot": True,
             "prefix_targets": True,
             "hash_algo": "sha256",
@@ -203,29 +204,29 @@ def test_download_targets(self, test_case_data: Dict[str, Any]):
         for targetpath in targetpaths:
             sim.targets.version += 1
             sim.add_target("targets", b"content", targetpath)
-            sim.update_snapshot()
+        sim.update_snapshot()
 
         updater = self._init_updater(sim)
         updater.config.prefix_targets_with_hash = prefix_targets_with_hash
         updater.refresh()
 
-        for targetpath in targetpaths:
-            info = updater.get_targetinfo(targetpath)
-
-            with patch.object(
-                sim, "_fetch_target", wraps=sim._fetch_target
+        with patch.object(
+            sim, "_fetch_target", wraps=sim._fetch_target
             ) as wrapped_fetch_target:
 
+            for targetpath in targetpaths:
+                info = updater.get_targetinfo(targetpath)
                 updater.download_target(info)
                 expected_prefix = (
                     None if not hash_algo else info.hashes[hash_algo]
                 )
                 # files are fetched with the expected hash prefix (or None)
-                wrapped_fetch_target.assert_called_with(
+                wrapped_fetch_target.assert_called_once_with(
                     info.path, expected_prefix
                 )
                 # target files are always persisted without hash prefix
                 self._assert_targets_files_exist([info.path])
+                wrapped_fetch_target.reset_mock()
 
         self._cleanup_dir(self.targets_dir)