!squash helpers

tests/helpers.py

@@ -0,0 +1,28 @@
+"""Tests for DocutilsView template view."""
+import typing as t
+
+from django.template.engine import Engine
+
+if t.TYPE_CHECKING:
+    import sys
+    import types
+
+    from typing_extensions import TypeAlias
+
+    # https://github.com/python/typeshed/blob/f7aa7b7/stdlib/builtins.pyi#L1461
+    if sys.version_info >= (3, 10):
+        _ClassInfo: TypeAlias = type | types.UnionType | tuple["_ClassInfo", ...]
+    else:
+        _ClassInfo: TypeAlias = type | tuple[_ClassInfo, ...]
+
+
+def get_template_engine(
+    using: "_ClassInfo",
+) -> None | Engine:
+    """Return Template Engine (e.g. DocutilsTemplates), for augmenting dirs in tests."""
+    from django.template import engines
+
+    for engine in engines.all():
+        if isinstance(engine, using):
+            return t.cast(Engine, engine.engine)  # type:ignore
+    return None