plotting|util|tests: Introduce chia.util.generator_tools.list_to_batches (#9304)

* plotting|util: Introduce `chia.util.generator_tools.list_to_batches`

* tests: Test `list_to_batches` in  `test_list_to_batches.py`

* util|tests: Return an empty iterator for empty input lists

* tests: Test list sizes from 1-10 in `test_valid`

chia/plotting/manager.py

@@ -4,7 +4,7 @@ import threading
 import time
 import traceback
 from pathlib import Path
-from typing import Any, Callable, Dict, List, Optional, Set, Tuple, Iterator
+from typing import Any, Callable, Dict, List, Optional, Set, Tuple
 from concurrent.futures.thread import ThreadPoolExecutor
 
 from blspy import G1Element
@@ -21,6 +21,7 @@ from chia.plotting.util import (
     stream_plot_info_pk,
     stream_plot_info_ph,
 )
+from chia.util.generator_tools import list_to_batches
 from chia.util.ints import uint16
 from chia.util.path import mkdir
 from chia.util.streamable import Streamable, streamable
@@ -258,15 +259,7 @@ class PlotManager:
             for filename in filenames_to_remove:
                 del self.plot_filename_paths[filename]
 
-            def batches() -> Iterator[Tuple[int, List[Path]]]:
+            for remaining, batch in list_to_batches(plot_paths, self.refresh_parameter.batch_size):
-                if total_size > 0:
-                    for batch_start in range(0, total_size, self.refresh_parameter.batch_size):
-                        batch_end = min(batch_start + self.refresh_parameter.batch_size, total_size)
-                        yield total_size - batch_end, plot_paths[batch_start:batch_end]
-                else:
-                    yield 0, []
-
-            for remaining, batch in batches():
                 batch_result: PlotRefreshResult = self.refresh_batch(batch, plot_directories)
                 if not self._refreshing_enabled:
                     self.log.debug("refresh_plots: Aborted")

chia/util/generator_tools.py

@@ -1,4 +1,4 @@
-from typing import List, Tuple
+from typing import Any, Iterator, List, Tuple
 from chiabip158 import PyBIP158
 
 from chia.types.blockchain_format.coin import Coin
@@ -64,3 +64,14 @@ def tx_removals_and_additions(npc_list: List[NPC]) -> Tuple[List[bytes32], List[
     additions.extend(additions_for_npc(npc_list))
 
     return removals, additions
+
+
+def list_to_batches(list_to_split: List[Any], batch_size: int) -> Iterator[Tuple[int, List[Any]]]:
+    if batch_size <= 0:
+        raise ValueError("list_to_batches: batch_size must be greater than 0.")
+    total_size = len(list_to_split)
+    if total_size == 0:
+        return iter(())
+    for batch_start in range(0, total_size, batch_size):
+        batch_end = min(batch_start + batch_size, total_size)
+        yield total_size - batch_end, list_to_split[batch_start:batch_end]

tests/generator/test_list_to_batches.py

@@ -0,0 +1,30 @@
+import pytest
+from chia.util.generator_tools import list_to_batches
+
+
+def test_empty_lists():
+    # An empty list should return an empty iterator and skip the loop's body.
+    for _, _ in list_to_batches([], 1):
+        assert False
+
+
+def test_valid():
+    for k in range(1, 10):
+        test_list = [x for x in range(0, k)]
+        for i in range(1, len(test_list) + 1):  # Test batch_size 1 to 11 (length + 1)
+            checked = 0
+            for remaining, batch in list_to_batches(test_list, i):
+                assert remaining == max(len(test_list) - checked - i, 0)
+                assert len(batch) <= i
+                assert batch == test_list[checked : min(checked + i, len(test_list))]
+                checked += len(batch)
+            assert checked == len(test_list)
+
+
+def test_invalid_batch_sizes():
+    with pytest.raises(ValueError):
+        for _ in list_to_batches([], 0):
+            assert False
+    with pytest.raises(ValueError):
+        for _ in list_to_batches([], -1):
+            assert False