Rename TestDevice -> FakeDevice to avoid pytest confusion (#5066)

Pytest tries to collect `TestDevice` as a test class, and fails with the following wraning:
```
cirq-core/cirq/circuits/circuit_dag_test.py:24
cirq-core/cirq/circuits/circuit_dag_test.py:24
  /home/runner/work/Cirq/Cirq/cirq-core/cirq/circuits/circuit_dag_test.py:24: PytestCollectionWarning: cannot collect test class 'TestDevice' because it has a __init__ constructor (from: cirq-core/cirq/circuits/circuit_dag_test.py)
    class TestDevice(cirq.Device):
```

cirq-core/cirq/circuits/circuit_dag_test.py

@@ -21,9 +21,8 @@
 import cirq
 
 
-class TestDevice(cirq.Device):
-    def __init__(self):
-        pass
+class FakeDevice(cirq.Device):
+    pass
 
 
 def test_wrapper_eq():
@@ -124,7 +123,7 @@ def test_from_ops_device_deprecated():
         cirq.circuits.circuit._DEVICE_DEP_MESSAGE, deadline='v0.15'
     ):
         q0 = cirq.LineQubit(0)
-        _ = cirq.CircuitDag.from_ops(cirq.X(q0), cirq.Y(q0), device=TestDevice())
+        _ = cirq.CircuitDag.from_ops(cirq.X(q0), cirq.Y(q0), device=FakeDevice())
 
 
 def test_from_circuit():
@@ -140,7 +139,7 @@ def test_from_circuit():
 def test_from_circuit_deprecated():
     q0 = cirq.LineQubit(0)
     circuit = cirq.Circuit(cirq.X(q0), cirq.Y(q0))
-    circuit._device = TestDevice()
+    circuit._device = FakeDevice()
     with cirq.testing.assert_deprecated(
         cirq.circuits.circuit._DEVICE_DEP_MESSAGE, deadline='v0.15'
     ):
@@ -172,7 +171,7 @@ def test_to_circuit_device_deprecated():
     q0 = cirq.LineQubit(0)
     circuit = cirq.Circuit(cirq.X(q0), cirq.Y(q0))
     dag = cirq.CircuitDag.from_circuit(circuit)
-    dag._device = TestDevice()
+    dag._device = FakeDevice()
 
     with cirq.testing.assert_deprecated(
         cirq.circuits.circuit._DEVICE_DEP_MESSAGE, deadline='v0.15'

cirq-core/cirq/circuits/circuit_test.py

@@ -208,15 +208,15 @@ def test_approx_eq(circuit_cls):
 
 @pytest.mark.parametrize('circuit_cls', [cirq.Circuit, cirq.FrozenCircuit])
 def test_approx_eq_device_deprecated(circuit_cls):
-    class TestDevice(cirq.Device):
+    class FakeDevice(cirq.Device):
         def validate_operation(self, operation: cirq.Operation) -> None:
             pass
 
     a = cirq.NamedQubit('a')
     with cirq.testing.assert_deprecated(
         cirq.circuits.circuit._DEVICE_DEP_MESSAGE, deadline='v0.15'
     ):
-        other_device = circuit_cls([cirq.Moment([cirq.X(a)])], device=TestDevice())
+        other_device = circuit_cls([cirq.Moment([cirq.X(a)])], device=FakeDevice())
     assert not cirq.approx_eq(
         circuit_cls([cirq.Moment([cirq.X(a)])]),
         other_device,

cirq-core/cirq/contrib/quantum_volume/quantum_volume_test.py

@@ -10,7 +10,7 @@
 from cirq.contrib.quantum_volume import CompilationResult
 
 
-class TestDevice(cirq.Device):
+class FakeDevice(cirq.Device):
     qubits = cirq.GridQubit.rect(5, 5)
 
 
@@ -123,7 +123,7 @@ def test_compile_circuit_router():
     router_mock = MagicMock()
     cirq.contrib.quantum_volume.compile_circuit(
         cirq.Circuit(),
-        device_graph=ccr.gridqubits_to_graph_device(TestDevice().qubits),
+        device_graph=ccr.gridqubits_to_graph_device(FakeDevice().qubits),
         router=router_mock,
         routing_attempts=1,
     )
@@ -141,15 +141,15 @@ def test_compile_circuit():
     )
     compilation_result = cirq.contrib.quantum_volume.compile_circuit(
         model_circuit,
-        device_graph=ccr.gridqubits_to_graph_device(TestDevice().qubits),
+        device_graph=ccr.gridqubits_to_graph_device(FakeDevice().qubits),
         compiler=compiler_mock,
         routing_attempts=1,
     )
 
     assert len(compilation_result.mapping) == 3
     assert cirq.contrib.routing.ops_are_consistent_with_device_graph(
         compilation_result.circuit.all_operations(),
-        cirq.contrib.routing.gridqubits_to_graph_device(TestDevice().qubits),
+        cirq.contrib.routing.gridqubits_to_graph_device(FakeDevice().qubits),
     )
     compiler_mock.assert_called_with(compilation_result.circuit)
 
@@ -169,7 +169,7 @@ def test_compile_circuit_replaces_swaps():
     )
     compilation_result = cirq.contrib.quantum_volume.compile_circuit(
         model_circuit,
-        device_graph=ccr.gridqubits_to_graph_device(TestDevice().qubits),
+        device_graph=ccr.gridqubits_to_graph_device(FakeDevice().qubits),
         compiler=compiler_mock,
         routing_attempts=1,
     )
@@ -209,7 +209,7 @@ def test_compile_circuit_with_readout_correction():
     )
     compilation_result = cirq.contrib.quantum_volume.compile_circuit(
         model_circuit,
-        device_graph=ccr.gridqubits_to_graph_device(TestDevice().qubits),
+        device_graph=ccr.gridqubits_to_graph_device(FakeDevice().qubits),
         compiler=compiler_mock,
         router=router_mock,
         routing_attempts=1,
@@ -258,7 +258,7 @@ def test_compile_circuit_multiple_routing_attempts():
 
     compilation_result = cirq.contrib.quantum_volume.compile_circuit(
         model_circuit,
-        device_graph=ccr.gridqubits_to_graph_device(TestDevice().qubits),
+        device_graph=ccr.gridqubits_to_graph_device(FakeDevice().qubits),
         compiler=compiler_mock,
         router=router_mock,
         routing_attempts=3,
@@ -281,7 +281,7 @@ def test_compile_circuit_no_routing_attempts():
     with pytest.raises(AssertionError) as e:
         cirq.contrib.quantum_volume.compile_circuit(
             model_circuit,
-            device_graph=ccr.gridqubits_to_graph_device(TestDevice().qubits),
+            device_graph=ccr.gridqubits_to_graph_device(FakeDevice().qubits),
             routing_attempts=0,
         )
     assert e.match('Unable to get routing for circuit')

cirq-google/cirq_google/line/placement/anneal_test.py

@@ -28,13 +28,13 @@
 from cirq_google.line.placement.chip import chip_as_adjacency_list
 
 
-class TestDevice(cirq.Device):
+class FakeDevice(cirq.Device):
     def __init__(self, qubits):
         self.qubits = qubits
 
 
 def _create_device(qubits: Iterable[cirq.GridQubit]):
-    return TestDevice(qubits)
+    return FakeDevice(qubits)
 
 
 @mock.patch('cirq_google.line.placement.optimization.anneal_minimize')

cirq-google/cirq_google/line/placement/chip_test.py

@@ -42,13 +42,13 @@ def test_qubit_not_mutated():
     assert qubit == cirq.GridQubit(0, 0)
 
 
-class TestDevice(cirq.Device):
+class FakeDevice(cirq.Device):
     def __init__(self, qubits):
         self.qubits = qubits
 
 
 def _create_device(qubits: Iterable[cirq.GridQubit]):
-    return TestDevice(qubits)
+    return FakeDevice(qubits)
 
 
 def test_empty():

cirq-google/cirq_google/line/placement/greedy_test.py

@@ -24,13 +24,13 @@
 )
 
 
-class TestDevice(cirq.Device):
+class FakeDevice(cirq.Device):
     def __init__(self, qubits):
         self.qubits = qubits
 
 
 def _create_device(qubits: Iterable[cirq.GridQubit]):
-    return TestDevice(qubits)
+    return FakeDevice(qubits)
 
 
 def test_greedy_sequence_search_fails_on_wrong_start_qubit():

cirq-google/cirq_google/line/placement/line_test.py

@@ -19,7 +19,7 @@
 from cirq_google.line.placement import GridQubitLineTuple
 
 
-class TestDevice(cirq.Device):
+class FakeDevice(cirq.Device):
     def __init__(self, qubits):
         self.qubits = qubits
 
@@ -28,7 +28,7 @@ def test_anneal_method_calls_anneal_search():
     q00 = cirq.GridQubit(0, 0)
     q01 = cirq.GridQubit(0, 1)
     q03 = cirq.GridQubit(0, 3)
-    device = TestDevice(qubits=[q00, q01, q03])
+    device = FakeDevice(qubits=[q00, q01, q03])
     length = 2
     method = cg.AnnealSequenceSearchStrategy()
 

cirq-google/cirq_google/optimizers/optimize_for_sycamore_test.py

@@ -19,7 +19,7 @@
 import cirq_google as cg
 
 
-class TestDevice(cirq.Device):
+class FakeDevice(cirq.Device):
     def __init__(self):
         pass
 
@@ -132,7 +132,7 @@ def test_assert_new_device_deprecated():
         cirq.circuits.circuit._DEVICE_DEP_MESSAGE, deadline='v0.15'
     ):
         _ = cg.optimized_for_sycamore(
-            circuit0, optimizer_type='sqrt_iswap', new_device=TestDevice()
+            circuit0, optimizer_type='sqrt_iswap', new_device=FakeDevice()
         )
 
 

cirq-google/cirq_google/serialization/circuit_serializer_test.py

@@ -22,7 +22,7 @@
 from cirq_google.api import v2
 
 
-class TestDevice(cirq.Device):
+class FakeDevice(cirq.Device):
     def __init__(self):
         pass
 
@@ -680,7 +680,7 @@ def test_deserialize_schedule_not_supported():
         ),
     )
     with pytest.raises(ValueError, match='no longer supported'):
-        serializer.deserialize(proto, TestDevice())
+        serializer.deserialize(proto, FakeDevice())
 
 
 def test_deserialize_fsim_missing_parameters():

cirq-google/cirq_google/workflow/qubit_placement_test.py

@@ -19,7 +19,7 @@
 import numpy as np
 
 
-class TestDevice(cirq.Device):
+class FakeDevice(cirq.Device):
     def __init__(self):
         self.qubits = cirq.GridQubit.rect(2, 8)
         neighbors = [(a, b) for a in self.qubits for b in self.qubits if a.is_adjacent(b)]
@@ -123,7 +123,7 @@ def test_random_device_placer_small_device():
         qp.place_circuit(
             circuit,
             problem_topology=topo,
-            shared_rt_info=cg.SharedRuntimeInfo(run_id='1', device=TestDevice()),
+            shared_rt_info=cg.SharedRuntimeInfo(run_id='1', device=FakeDevice()),
             rs=np.random.RandomState(1),
         )