Fix selection_registers in qubitization_walk_test (#1350)

Author: charlesyuan314

qualtran/bloqs/for_testing/qubitization_walk_test.py

@@ -19,7 +19,7 @@
 import scipy
 from numpy.typing import NDArray
 
-from qualtran import Signature
+from qualtran import BoundedQUInt, Register
 from qualtran.bloqs.block_encoding.lcu_block_encoding import SelectBlockEncoding
 from qualtran.bloqs.multiplexers.select_pauli_lcu import SelectPauliLCU
 from qualtran.bloqs.qubitization.qubitization_walk_operator import QubitizationWalkOperator
@@ -37,12 +37,12 @@ class PrepareUniformSuperpositionTest(PrepareOracle):
     qlambda: float = 0.0
 
     @cached_property
-    def selection_registers(self) -> Signature:
-        return Signature.build(selection=(self.n - 1).bit_length())
+    def selection_registers(self) -> Tuple[Register, ...]:
+        return (Register('selection', BoundedQUInt((self.n - 1).bit_length(), self.n)),)
 
     @cached_property
-    def junk_registers(self) -> Signature:
-        return Signature.build()
+    def junk_registers(self) -> Tuple[Register, ...]:
+        return ()
 
     @cached_property
     def l1_norm_of_coeffs(self) -> SymbolicFloat: