Only convert to an indexable sequence if absolutely necessary

src/textual/_collections.py

@@ -1,7 +1,7 @@
 """Provides collection-based utility code."""
 
 from __future__ import annotations
-from typing import Generic, TypeVar, Iterator, overload, Iterable
+from typing import Generic, TypeVar, Iterator, overload, Iterable, Sequence
 
 T = TypeVar("T")
 
@@ -15,7 +15,7 @@ class ImmutableSequence(Generic[T]):
         Args:
             wrap (Iterable[T]): The iterable value being wrapped.
         """
-        self._wrap = tuple(wrap)
+        self._wrap = wrap if isinstance(wrap, Sequence) else tuple(wrap)
 
     @overload
     def __getitem__(self, index: int) -> T:

tests/test_collections.py

@@ -57,10 +57,11 @@ def test_get_item_from_immutable_sequence() -> None:
     assert wrap(range(10))[0] == 0
     assert wrap(range(10))[-1] == 9
 
+
 def test_get_slice_from_immutable_sequence() -> None:
     """It should be possible to get a slice from an immutable sequence."""
-    assert list(wrap(range(10))[0:2]) == [0,1]
+    assert list(wrap(iter(range(10)))[0:2]) == [0,1]
-    assert list(wrap(range(10))[0:-1]) == [0,1,2,3,4,5,6,7,8]
+    assert list(wrap(iter(range(10)))[0:-1]) == [0,1,2,3,4,5,6,7,8]
 
 
 def test_immutable_sequence_contains() -> None: