Add template function: shuffle (#140077)

homeassistant/helpers/template.py

@@ -6,7 +6,7 @@ from ast import literal_eval
 import asyncio
 import base64
 import collections.abc
-from collections.abc import Callable, Generator, Iterable
+from collections.abc import Callable, Generator, Iterable, MutableSequence
 from contextlib import AbstractContextManager
 from contextvars import ContextVar
 from copy import deepcopy
@@ -2736,6 +2736,30 @@ def iif(
     return if_false
 
 
+def shuffle(*args: Any, seed: Any = None) -> MutableSequence[Any]:
+    """Shuffle a list, either with a seed or without."""
+    if not args:
+        raise TypeError("shuffle expected at least 1 argument, got 0")
+
+    # If first argument is iterable and more than 1 argument provided
+    # but not a named seed, then use 2nd argument as seed.
+    if isinstance(args[0], Iterable):
+        items = list(args[0])
+        if len(args) > 1 and seed is None:
+            seed = args[1]
+    elif len(args) == 1:
+        raise TypeError(f"'{type(args[0]).__name__}' object is not iterable")
+    else:
+        items = list(args)
+
+    if seed:
+        r = random.Random(seed)
+        r.shuffle(items)
+    else:
+        random.shuffle(items)
+    return items
+
+
 class TemplateContextManager(AbstractContextManager):
     """Context manager to store template being parsed or rendered in a ContextVar."""
 
@@ -2936,6 +2960,7 @@ class TemplateEnvironment(ImmutableSandboxedEnvironment):
         self.filters["bool"] = forgiving_boolean
         self.filters["version"] = version
         self.filters["contains"] = contains
+        self.filters["shuffle"] = shuffle
         self.globals["log"] = logarithm
         self.globals["sin"] = sine
         self.globals["cos"] = cosine
@@ -2973,6 +2998,7 @@ class TemplateEnvironment(ImmutableSandboxedEnvironment):
         self.globals["bool"] = forgiving_boolean
         self.globals["version"] = version
         self.globals["zip"] = zip
+        self.globals["shuffle"] = shuffle
         self.tests["is_number"] = is_number
         self.tests["list"] = _is_list
         self.tests["set"] = _is_set

tests/helpers/test_template.py

@@ -15,6 +15,7 @@ from unittest.mock import patch
 from freezegun import freeze_time
 import orjson
 import pytest
+from pytest_unordered import unordered
 from syrupy import SnapshotAssertion
 import voluptuous as vol
 
@@ -6672,3 +6673,54 @@ async def test_merge_response_not_mutate_original_object(
 
     tpl = template.Template(_template, hass)
     assert tpl.async_render()
+
+
+def test_shuffle(hass: HomeAssistant) -> None:
+    """Test the shuffle function and filter."""
+    assert list(
+        template.Template("{{ [1, 2, 3] | shuffle }}", hass).async_render()
+    ) == unordered([1, 2, 3])
+
+    assert list(
+        template.Template("{{ shuffle([1, 2, 3]) }}", hass).async_render()
+    ) == unordered([1, 2, 3])
+
+    assert list(
+        template.Template("{{ shuffle(1, 2, 3) }}", hass).async_render()
+    ) == unordered([1, 2, 3])
+
+    assert list(template.Template("{{ shuffle([]) }}", hass).async_render()) == []
+
+    assert list(template.Template("{{ [] | shuffle }}", hass).async_render()) == []
+
+    # Testing using seed
+    assert list(
+        template.Template("{{ shuffle([1, 2, 3], 'seed') }}", hass).async_render()
+    ) == [2, 3, 1]
+
+    assert list(
+        template.Template(
+            "{{ shuffle([1, 2, 3], seed='seed') }}",
+            hass,
+        ).async_render()
+    ) == [2, 3, 1]
+
+    assert list(
+        template.Template(
+            "{{ [1, 2, 3] | shuffle('seed') }}",
+            hass,
+        ).async_render()
+    ) == [2, 3, 1]
+
+    assert list(
+        template.Template(
+            "{{ [1, 2, 3] | shuffle(seed='seed') }}",
+            hass,
+        ).async_render()
+    ) == [2, 3, 1]
+
+    with pytest.raises(TemplateError):
+        template.Template("{{ 1 | shuffle }}", hass).async_render()
+
+    with pytest.raises(TemplateError):
+        template.Template("{{ shuffle() }}", hass).async_render()