sync: Implement --interleaved sync worker

For each assigned project, the worker sequentially calls
Sync_NetworkHalf and Sync_LocalHalf, respecting --local-only and
--network-only flags. To prevent scrambled progress bars, all stderr
output from the checkout phase is captured (shown with --verbose).
Result objects now carry status and timing information from the worker
for state updates.

Bug: 421935613
Change-Id: I398602e08a375e974a8914e5fa48ffae673dda9b
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/483301
Commit-Queue: Gavin Mak <gavinmak@google.com>
Reviewed-by: Scott Lee <ddoman@google.com>
Tested-by: Gavin Mak <gavinmak@google.com>

3 files changed, 483 insertions, 114 deletions

diff --git a/progress.py b/progress.py
index fe246c74..a386f426 100644
--- a/progress.py
+++ b/progress.py
@@ -195,6 +195,21 @@ class Progress:
                 )
             )
 
+    def display_message(self, msg):
+        """Clears the current progress line and prints a message above it.
+
+        The progress bar is then redrawn on the next line.
+        """
+        if not _TTY or IsTraceToStderr() or self._quiet:
+            return
+
+        # Erase the current line, print the message with a newline,
+        # and then immediately redraw the progress bar on the new line.
+        sys.stderr.write("\r" + CSI_ERASE_LINE)
+        sys.stderr.write(msg + "\n")
+        sys.stderr.flush()
+        self.update(inc=0)
+
     def end(self):
         self._update_event.set()
         if not _TTY or IsTraceToStderr() or self._quiet:
diff --git a/subcmds/sync.py b/subcmds/sync.py
index 711baca2..f0c398a3 100644
--- a/subcmds/sync.py
+++ b/subcmds/sync.py
@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import collections
+import contextlib
 import functools
 import http.cookiejar as cookielib
 import io
@@ -198,33 +199,41 @@ class _SyncResult(NamedTuple):
     """Individual project sync result for interleaved mode.
 
     Attributes:
+      project_index (int): The index of the project in the shared list.
       relpath (str): The project's relative path from the repo client top.
+      remote_fetched (bool): True if the remote was actually queried.
       fetch_success (bool): True if the fetch operation was successful.
-      checkout_success (bool): True if the checkout operation was
-          successful.
       fetch_error (Optional[Exception]): The Exception from a failed fetch,
           or None.
-      checkout_error (Optional[Exception]): The Exception from a failed
-          checkout, or None.
       fetch_start (Optional[float]): The time.time() when fetch started.
       fetch_finish (Optional[float]): The time.time() when fetch finished.
+      checkout_success (bool): True if the checkout operation was
+          successful.
+      checkout_error (Optional[Exception]): The Exception from a failed
+          checkout, or None.
       checkout_start (Optional[float]): The time.time() when checkout
           started.
       checkout_finish (Optional[float]): The time.time() when checkout
           finished.
+      stderr_text (str): The combined output from both fetch and checkout.
     """
 
+    project_index: int
     relpath: str
+
+    remote_fetched: bool
     fetch_success: bool
-    checkout_success: bool
     fetch_error: Optional[Exception]
-    checkout_error: Optional[Exception]
-
     fetch_start: Optional[float]
     fetch_finish: Optional[float]
+
+    checkout_success: bool
+    checkout_error: Optional[Exception]
     checkout_start: Optional[float]
     checkout_finish: Optional[float]
 
+    stderr_text: str
+
 
 class _InterleavedSyncResult(NamedTuple):
     """Result of an interleaved sync.
@@ -996,6 +1005,7 @@ later is required to fix a server side protocol bug.
             err_event.set()
 
         # Call self update, unless requested not to
+        # TODO(b/42193561): Extract repo update logic to ExecuteHelper.
         if os.environ.get("REPO_SKIP_SELF_UPDATE", "0") == "0":
             _PostRepoFetch(rp, opt.repo_verify)
         if opt.network_only:
@@ -1176,6 +1186,16 @@ later is required to fix a server side protocol bug.
         self._local_sync_state.Save()
         return proc_res and not err_results
 
+    def _PrintManifestNotices(self, opt):
+        """Print all manifest notices, but only once."""
+        printed_notices = set()
+        # Print all manifest notices, but only once.
+        # Sort by path_prefix to ensure consistent ordering.
+        for m in sorted(self.ManifestList(opt), key=lambda x: x.path_prefix):
+            if m.notice and m.notice not in printed_notices:
+                print(m.notice)
+                printed_notices.add(m.notice)
+
     @staticmethod
     def _GetPreciousObjectsState(project: Project, opt):
         """Get the preciousObjects state for the project.
@@ -2032,14 +2052,7 @@ later is required to fix a server side protocol bug.
         if err_checkout:
             err_event.set()
 
-        printed_notices = set()
-        # If there's a notice that's supposed to print at the end of the sync,
-        # print it now...  But avoid printing duplicate messages, and preserve
-        # order.
-        for m in sorted(self.ManifestList(opt), key=lambda x: x.path_prefix):
-            if m.notice and m.notice not in printed_notices:
-                print(m.notice)
-                printed_notices.add(m.notice)
+        self._PrintManifestNotices(opt)
 
         # If we saw an error, exit with code 1 so that other scripts can check.
         if err_event.is_set():
@@ -2068,6 +2081,139 @@ later is required to fix a server side protocol bug.
             raise SyncError(aggregate_errors=errors)
 
     @classmethod
+    def _SyncOneProject(cls, opt, project_index, project) -> _SyncResult:
+        """Syncs a single project for interleaved sync."""
+        fetch_success = False
+        remote_fetched = False
+        fetch_error = None
+        fetch_start = None
+        fetch_finish = None
+        network_output = ""
+
+        if opt.local_only:
+            fetch_success = True
+        else:
+            fetch_start = time.time()
+            network_output_capture = io.StringIO()
+            try:
+                ssh_proxy = cls.get_parallel_context().get("ssh_proxy")
+                sync_result = project.Sync_NetworkHalf(
+                    quiet=opt.quiet,
+                    verbose=opt.verbose,
+                    output_redir=network_output_capture,
+                    current_branch_only=cls._GetCurrentBranchOnly(
+                        opt, project.manifest
+                    ),
+                    force_sync=opt.force_sync,
+                    clone_bundle=opt.clone_bundle,
+                    tags=opt.tags,
+                    archive=project.manifest.IsArchive,
+                    optimized_fetch=opt.optimized_fetch,
+                    retry_fetches=opt.retry_fetches,
+                    prune=opt.prune,
+                    ssh_proxy=ssh_proxy,
+                    clone_filter=project.manifest.CloneFilter,
+                    partial_clone_exclude=project.manifest.PartialCloneExclude,
+                    clone_filter_for_depth=project.manifest.CloneFilterForDepth,
+                )
+                fetch_success = sync_result.success
+                remote_fetched = sync_result.remote_fetched
+                fetch_error = sync_result.error
+            except KeyboardInterrupt:
+                logger.error(
+                    "Keyboard interrupt while processing %s", project.name
+                )
+            except GitError as e:
+                fetch_error = e
+                logger.error("error.GitError: Cannot fetch %s", e)
+            except Exception as e:
+                fetch_error = e
+                logger.error(
+                    "error: Cannot fetch %s (%s: %s)",
+                    project.name,
+                    type(e).__name__,
+                    e,
+                )
+            finally:
+                fetch_finish = time.time()
+                network_output = network_output_capture.getvalue()
+
+        checkout_success = False
+        checkout_error = None
+        checkout_start = None
+        checkout_finish = None
+        checkout_stderr = ""
+
+        if fetch_success and not opt.network_only:
+            checkout_start = time.time()
+            stderr_capture = io.StringIO()
+            try:
+                with contextlib.redirect_stderr(stderr_capture):
+                    syncbuf = SyncBuffer(
+                        project.manifest.manifestProject.config,
+                        detach_head=opt.detach_head,
+                    )
+                    local_half_errors = []
+                    project.Sync_LocalHalf(
+                        syncbuf,
+                        force_sync=opt.force_sync,
+                        force_checkout=opt.force_checkout,
+                        force_rebase=opt.rebase,
+                        errors=local_half_errors,
+                        verbose=opt.verbose,
+                    )
+                    checkout_success = syncbuf.Finish()
+                    if local_half_errors:
+                        checkout_error = SyncError(
+                            aggregate_errors=local_half_errors
+                        )
+            except KeyboardInterrupt:
+                logger.error(
+                    "Keyboard interrupt while processing %s", project.name
+                )
+            except GitError as e:
+                checkout_error = e
+                logger.error(
+                    "error.GitError: Cannot checkout %s: %s", project.name, e
+                )
+            except Exception as e:
+                checkout_error = e
+                logger.error(
+                    "error: Cannot checkout %s: %s: %s",
+                    project.name,
+                    type(e).__name__,
+                    e,
+                )
+            finally:
+                checkout_finish = time.time()
+                checkout_stderr = stderr_capture.getvalue()
+        elif fetch_success:
+            checkout_success = True
+
+        # Consolidate all captured output.
+        captured_parts = []
+        if network_output:
+            captured_parts.append(network_output)
+        if checkout_stderr:
+            captured_parts.append(checkout_stderr)
+        stderr_text = "\n".join(captured_parts)
+
+        return _SyncResult(
+            project_index=project_index,
+            relpath=project.relpath,
+            fetch_success=fetch_success,
+            remote_fetched=remote_fetched,
+            checkout_success=checkout_success,
+            fetch_error=fetch_error,
+            checkout_error=checkout_error,
+            stderr_text=stderr_text.strip(),
+            fetch_start=fetch_start,
+            fetch_finish=fetch_finish,
+            checkout_start=checkout_start,
+            checkout_finish=checkout_finish,
+        )
+
+    @classmethod
     def _SyncProjectList(cls, opt, project_indices) -> _InterleavedSyncResult:
         """Worker for interleaved sync.
 
@@ -2092,27 +2238,12 @@ later is required to fix a server side protocol bug.
         # Use the first project as the representative for the progress bar.
         first_project = projects[project_indices[0]]
         key = f"{first_project.name} @ {first_project.relpath}"
-        start_time = time.time()
-        sync_dict[key] = start_time
+        sync_dict[key] = time.time()
 
         try:
             for idx in project_indices:
                 project = projects[idx]
-                # For now, simulate a successful sync.
-                # TODO(b/421935613): Perform the actual git fetch and checkout.
-                results.append(
-                    _SyncResult(
-                        relpath=project.relpath,
-                        fetch_success=True,
-                        checkout_success=True,
-                        fetch_error=None,
-                        checkout_error=None,
-                        fetch_start=None,
-                        fetch_finish=None,
-                        checkout_start=None,
-                        checkout_finish=None,
-                    )
-                )
+                results.append(cls._SyncOneProject(opt, idx, project))
         finally:
             del sync_dict[key]
 
@@ -2130,9 +2261,39 @@ later is required to fix a server side protocol bug.
     ):
         """Callback to process results from interleaved sync workers."""
         ret = True
+        projects = self.get_parallel_context()["projects"]
         for result_group in results_sets:
             for result in result_group.results:
                 pm.update()
+                project = projects[result.project_index]
+
+                if opt.verbose and result.stderr_text:
+                    pm.display_message(result.stderr_text)
+
+                if result.fetch_start:
+                    self._fetch_times.Set(
+                        project,
+                        result.fetch_finish - result.fetch_start,
+                    )
+                    self._local_sync_state.SetFetchTime(project)
+                    self.event_log.AddSync(
+                        project,
+                        event_log.TASK_SYNC_NETWORK,
+                        result.fetch_start,
+                        result.fetch_finish,
+                        result.fetch_success,
+                    )
+                if result.checkout_start:
+                    if result.checkout_success:
+                        self._local_sync_state.SetCheckoutTime(project)
+                    self.event_log.AddSync(
+                        project,
+                        event_log.TASK_SYNC_LOCAL,
+                        result.checkout_start,
+                        result.checkout_finish,
+                        result.checkout_success,
+                    )
+
                 if result.fetch_success and result.checkout_success:
                     synced_relpaths.add(result.relpath)
                 else:
@@ -2188,96 +2349,110 @@ later is required to fix a server side protocol bug.
         sync_event = _threading.Event()
         sync_progress_thread = self._CreateSyncProgressThread(pm, sync_event)
 
-        with self.ParallelContext():
-            # TODO(gavinmak): Use multprocessing.Queue instead of dict.
-            self.get_parallel_context()[
-                "sync_dict"
-            ] = multiprocessing.Manager().dict()
-            sync_progress_thread.start()
+        with multiprocessing.Manager() as manager, ssh.ProxyManager(
+            manager
+        ) as ssh_proxy:
+            ssh_proxy.sock()
+            with self.ParallelContext():
+                self.get_parallel_context()["ssh_proxy"] = ssh_proxy
+                # TODO(gavinmak): Use multprocessing.Queue instead of dict.
+                self.get_parallel_context()[
+                    "sync_dict"
+                ] = multiprocessing.Manager().dict()
+                sync_progress_thread.start()
 
-            try:
-                # Outer loop for dynamic project discovery (e.g., submodules).
-                # It continues until no unsynced projects remain.
-                while True:
-                    projects_to_sync = [
-                        p
-                        for p in project_list
-                        if p.relpath not in synced_relpaths
-                    ]
-                    if not projects_to_sync:
-                        break
-
-                    pending_relpaths = {p.relpath for p in projects_to_sync}
-                    if previously_pending_relpaths == pending_relpaths:
-                        logger.error(
-                            "Stall detected in interleaved sync, not all "
-                            "projects could be synced."
-                        )
-                        err_event.set()
-                        break
-                    previously_pending_relpaths = pending_relpaths
-
-                    # Update the projects list for workers in the current pass.
-                    self.get_parallel_context()["projects"] = projects_to_sync
-                    project_index_map = {
-                        p: i for i, p in enumerate(projects_to_sync)
-                    }
-
-                    # Inner loop to process projects in a hierarchical order.
-                    # This iterates through levels of project dependencies (e.g.
-                    # 'foo' then 'foo/bar'). All projects in one level can be
-                    # processed in parallel, but we must wait for a level to
-                    # complete before starting the next.
-                    for level_projects in _SafeCheckoutOrder(projects_to_sync):
-                        if not level_projects:
-                            continue
-
-                        objdir_project_map = collections.defaultdict(list)
-                        for p in level_projects:
-                            objdir_project_map[p.objdir].append(
-                                project_index_map[p]
+                try:
+                    # Outer loop for dynamic project discovery. This continues
+                    # until no unsynced projects remain.
+                    while True:
+                        projects_to_sync = [
+                            p
+                            for p in project_list
+                            if p.relpath not in synced_relpaths
+                        ]
+                        if not projects_to_sync:
+                            break
+
+                        pending_relpaths = {p.relpath for p in projects_to_sync}
+                        if previously_pending_relpaths == pending_relpaths:
+                            logger.error(
+                                "Stall detected in interleaved sync, not all "
+                                "projects could be synced."
                             )
-
-                        work_items = list(objdir_project_map.values())
-                        if not work_items:
-                            continue
-
-                        jobs = max(1, min(opt.jobs, len(work_items)))
-                        callback = functools.partial(
-                            self._ProcessSyncInterleavedResults,
-                            synced_relpaths,
-                            err_event,
-                            errors,
-                            opt,
-                        )
-                        if not self.ExecuteInParallel(
-                            jobs,
-                            functools.partial(self._SyncProjectList, opt),
-                            work_items,
-                            callback=callback,
-                            output=pm,
-                            chunksize=1,
-                        ):
                             err_event.set()
+                            break
+                        previously_pending_relpaths = pending_relpaths
+
+                        self.get_parallel_context()[
+                            "projects"
+                        ] = projects_to_sync
+                        project_index_map = {
+                            p: i for i, p in enumerate(projects_to_sync)
+                        }
+
+                        # Inner loop to process projects in a hierarchical
+                        # order. This iterates through levels of project
+                        # dependencies (e.g. 'foo' then 'foo/bar'). All projects
+                        # in one level can be processed in parallel, but we must
+                        # wait for a level to complete before starting the next.
+                        for level_projects in _SafeCheckoutOrder(
+                            projects_to_sync
+                        ):
+                            if not level_projects:
+                                continue
 
-                        if err_event.is_set() and opt.fail_fast:
-                            raise SyncFailFastError(aggregate_errors=errors)
+                            objdir_project_map = collections.defaultdict(list)
+                            for p in level_projects:
+                                objdir_project_map[p.objdir].append(
+                                    project_index_map[p]
+                                )
 
-                    self._ReloadManifest(None, manifest)
-                    project_list = self.GetProjects(
-                        args,
-                        missing_ok=True,
-                        submodules_ok=opt.fetch_submodules,
-                        manifest=manifest,
-                        all_manifests=not opt.this_manifest_only,
-                    )
-            finally:
-                sync_event.set()
-                sync_progress_thread.join()
+                            work_items = list(objdir_project_map.values())
+                            if not work_items:
+                                continue
+
+                            jobs = max(1, min(opt.jobs, len(work_items)))
+                            callback = functools.partial(
+                                self._ProcessSyncInterleavedResults,
+                                synced_relpaths,
+                                err_event,
+                                errors,
+                                opt,
+                            )
+                            if not self.ExecuteInParallel(
+                                jobs,
+                                functools.partial(self._SyncProjectList, opt),
+                                work_items,
+                                callback=callback,
+                                output=pm,
+                                chunksize=1,
+                            ):
+                                err_event.set()
+
+                            if err_event.is_set() and opt.fail_fast:
+                                raise SyncFailFastError(aggregate_errors=errors)
+
+                        self._ReloadManifest(None, manifest)
+                        project_list = self.GetProjects(
+                            args,
+                            missing_ok=True,
+                            submodules_ok=opt.fetch_submodules,
+                            manifest=manifest,
+                            all_manifests=not opt.this_manifest_only,
+                        )
+                finally:
+                    sync_event.set()
+                    sync_progress_thread.join()
 
         pm.end()
 
+        # TODO(b/421935613): Add the manifest loop block from PhasedSync.
+        if not self.outer_client.manifest.IsArchive:
+            self._GCProjects(project_list, opt, err_event)
+
+        self._PrintManifestNotices(opt)
         if err_event.is_set():
+            # TODO(b/421935613): Log errors better like SyncPhased.
             logger.error(
                 "error: Unable to fully sync the tree in interleaved mode."
             )
diff --git a/tests/test_subcmds_sync.py b/tests/test_subcmds_sync.py
index 60f283af..e7213ed9 100644
--- a/tests/test_subcmds_sync.py
+++ b/tests/test_subcmds_sync.py
@@ -310,6 +310,16 @@ class FakeProject:
         self.name = name or relpath
         self.objdir = objdir or relpath
 
+        self.use_git_worktrees = False
+        self.UseAlternates = False
+        self.manifest = mock.MagicMock()
+        self.manifest.GetProjectsWithName.return_value = [self]
+        self.config = mock.MagicMock()
+        self.EnableRepositoryExtension = mock.MagicMock()
+
+    def RelPath(self, local=None):
+        return self.relpath
+
     def __str__(self):
         return f"project: {self.relpath}"
 
@@ -531,7 +541,11 @@ class InterleavedSyncTest(unittest.TestCase):
         self.manifest.CloneBundle = False
         self.manifest.default.sync_j = 1
 
-        self.cmd = sync.Sync(manifest=self.manifest)
+        self.outer_client = mock.MagicMock()
+        self.outer_client.manifest.IsArchive = False
+        self.cmd = sync.Sync(
+            manifest=self.manifest, outer_client=self.outer_client
+        )
         self.cmd.outer_manifest = self.manifest
 
         # Mock projects.
@@ -549,6 +563,21 @@ class InterleavedSyncTest(unittest.TestCase):
         mock.patch.object(sync, "_PostRepoUpgrade").start()
         mock.patch.object(sync, "_PostRepoFetch").start()
 
+        # Mock parallel context for worker tests.
+        self.parallel_context_patcher = mock.patch(
+            "subcmds.sync.Sync.get_parallel_context"
+        )
+        self.mock_get_parallel_context = self.parallel_context_patcher.start()
+        self.sync_dict = {}
+        self.mock_context = {
+            "projects": [],
+            "sync_dict": self.sync_dict,
+        }
+        self.mock_get_parallel_context.return_value = self.mock_context
+
+        # Mock _GetCurrentBranchOnly for worker tests.
+        mock.patch.object(sync.Sync, "_GetCurrentBranchOnly").start()
+
     def tearDown(self):
         """Clean up resources."""
         shutil.rmtree(self.repodir)
@@ -635,3 +664,153 @@ class InterleavedSyncTest(unittest.TestCase):
         work_items_sets = {frozenset(item) for item in work_items}
         expected_sets = {frozenset([0, 2]), frozenset([1])}
         self.assertEqual(work_items_sets, expected_sets)
+
+    def _get_opts(self, args=None):
+        """Helper to get default options for worker tests."""
+        if args is None:
+            args = ["--interleaved"]
+        opt, _ = self.cmd.OptionParser.parse_args(args)
+        # Set defaults for options used by the worker.
+        opt.quiet = True
+        opt.verbose = False
+        opt.force_sync = False
+        opt.clone_bundle = False
+        opt.tags = False
+        opt.optimized_fetch = False
+        opt.retry_fetches = 0
+        opt.prune = False
+        opt.detach_head = False
+        opt.force_checkout = False
+        opt.rebase = False
+        return opt
+
+    def test_worker_successful_sync(self):
+        """Test _SyncProjectList with a successful fetch and checkout."""
+        opt = self._get_opts()
+        project = self.projA
+        project.Sync_NetworkHalf = mock.Mock(
+            return_value=SyncNetworkHalfResult(error=None, remote_fetched=True)
+        )
+        project.Sync_LocalHalf = mock.Mock()
+        project.manifest.manifestProject.config = mock.MagicMock()
+        self.mock_context["projects"] = [project]
+
+        with mock.patch("subcmds.sync.SyncBuffer") as mock_sync_buffer:
+            mock_sync_buf_instance = mock.MagicMock()
+            mock_sync_buf_instance.Finish.return_value = True
+            mock_sync_buffer.return_value = mock_sync_buf_instance
+
+            result_obj = self.cmd._SyncProjectList(opt, [0])
+
+            self.assertEqual(len(result_obj.results), 1)
+            result = result_obj.results[0]
+            self.assertTrue(result.fetch_success)
+            self.assertTrue(result.checkout_success)
+            self.assertIsNone(result.fetch_error)
+            self.assertIsNone(result.checkout_error)
+            project.Sync_NetworkHalf.assert_called_once()
+            project.Sync_LocalHalf.assert_called_once()
+
+    def test_worker_fetch_fails(self):
+        """Test _SyncProjectList with a failed fetch."""
+        opt = self._get_opts()
+        project = self.projA
+        fetch_error = GitError("Fetch failed")
+        project.Sync_NetworkHalf = mock.Mock(
+            return_value=SyncNetworkHalfResult(
+                error=fetch_error, remote_fetched=False
+            )
+        )
+        project.Sync_LocalHalf = mock.Mock()
+        self.mock_context["projects"] = [project]
+
+        result_obj = self.cmd._SyncProjectList(opt, [0])
+        result = result_obj.results[0]
+
+        self.assertFalse(result.fetch_success)
+        self.assertFalse(result.checkout_success)
+        self.assertEqual(result.fetch_error, fetch_error)
+        self.assertIsNone(result.checkout_error)
+        project.Sync_NetworkHalf.assert_called_once()
+        project.Sync_LocalHalf.assert_not_called()
+
+    def test_worker_fetch_fails_exception(self):
+        """Test _SyncProjectList with an exception during fetch."""
+        opt = self._get_opts()
+        project = self.projA
+        fetch_error = GitError("Fetch failed")
+        project.Sync_NetworkHalf = mock.Mock(side_effect=fetch_error)
+        project.Sync_LocalHalf = mock.Mock()
+        self.mock_context["projects"] = [project]
+
+        result_obj = self.cmd._SyncProjectList(opt, [0])
+        result = result_obj.results[0]
+
+        self.assertFalse(result.fetch_success)
+        self.assertFalse(result.checkout_success)
+        self.assertEqual(result.fetch_error, fetch_error)
+        project.Sync_NetworkHalf.assert_called_once()
+        project.Sync_LocalHalf.assert_not_called()
+
+    def test_worker_checkout_fails(self):
+        """Test _SyncProjectList with an exception during checkout."""
+        opt = self._get_opts()
+        project = self.projA
+        project.Sync_NetworkHalf = mock.Mock(
+            return_value=SyncNetworkHalfResult(error=None, remote_fetched=True)
+        )
+        checkout_error = GitError("Checkout failed")
+        project.Sync_LocalHalf = mock.Mock(side_effect=checkout_error)
+        project.manifest.manifestProject.config = mock.MagicMock()
+        self.mock_context["projects"] = [project]
+
+        with mock.patch("subcmds.sync.SyncBuffer"):
+            result_obj = self.cmd._SyncProjectList(opt, [0])
+            result = result_obj.results[0]
+
+            self.assertTrue(result.fetch_success)
+            self.assertFalse(result.checkout_success)
+            self.assertIsNone(result.fetch_error)
+            self.assertEqual(result.checkout_error, checkout_error)
+            project.Sync_NetworkHalf.assert_called_once()
+            project.Sync_LocalHalf.assert_called_once()
+
+    def test_worker_local_only(self):
+        """Test _SyncProjectList with --local-only."""
+        opt = self._get_opts(["--interleaved", "--local-only"])
+        project = self.projA
+        project.Sync_NetworkHalf = mock.Mock()
+        project.Sync_LocalHalf = mock.Mock()
+        project.manifest.manifestProject.config = mock.MagicMock()
+        self.mock_context["projects"] = [project]
+
+        with mock.patch("subcmds.sync.SyncBuffer") as mock_sync_buffer:
+            mock_sync_buf_instance = mock.MagicMock()
+            mock_sync_buf_instance.Finish.return_value = True
+            mock_sync_buffer.return_value = mock_sync_buf_instance
+
+            result_obj = self.cmd._SyncProjectList(opt, [0])
+            result = result_obj.results[0]
+
+            self.assertTrue(result.fetch_success)
+            self.assertTrue(result.checkout_success)
+            project.Sync_NetworkHalf.assert_not_called()
+            project.Sync_LocalHalf.assert_called_once()
+
+    def test_worker_network_only(self):
+        """Test _SyncProjectList with --network-only."""
+        opt = self._get_opts(["--interleaved", "--network-only"])
+        project = self.projA
+        project.Sync_NetworkHalf = mock.Mock(
+            return_value=SyncNetworkHalfResult(error=None, remote_fetched=True)
+        )
+        project.Sync_LocalHalf = mock.Mock()
+        self.mock_context["projects"] = [project]
+
+        result_obj = self.cmd._SyncProjectList(opt, [0])
+        result = result_obj.results[0]
+
+        self.assertTrue(result.fetch_success)
+        self.assertTrue(result.checkout_success)
+        project.Sync_NetworkHalf.assert_called_once()
+        project.Sync_LocalHalf.assert_not_called()