fix some bug when qiskit or cirq is not installed

Author: refraction-ray

tensorcircuit/results/qem/qem_methods.py

@@ -14,7 +14,6 @@
 logger = logging.getLogger(__name__)
 
 import numpy as np
-import cirq
 
 try:
     from mitiq import zne, ddd
@@ -205,6 +204,8 @@ def dd_rule(slack_length: int, spacing: int = -1) -> Any:
         return dd_sequence
 
     if isinstance(rule, list):
+        import cirq
+
         gates = []
         for i in rule:
             gates.append(getattr(cirq, i))

tensorcircuit/translation.py

@@ -27,6 +27,7 @@
         "Please first ``pip install -U qiskit`` to enable related functionality in translation module"
     )
     CircuitInstruction = Any
+    QuantumCircuit = Any
 
 try:
     import cirq

tests/test_torchnn.py

@@ -14,7 +14,7 @@
 try:
     import torch
 except ImportError:
-    pytest.skip("torch is not installed")
+    pytest.skip("torch is not installed", allow_module_level=True)
 
 
 @pytest.mark.parametrize("backend", [lf("tfb"), lf("jaxb"), lf("torchb")])