Add tests of all cached properties

Author: maffoo

Diff for: cirq-core/cirq/circuits/circuit.py

@@ -1839,7 +1839,6 @@ def _load_contents_with_earliest_strategy(self, contents: 'cirq.OP_TREE'):
                 self._moments.append(moments_by_index[i].with_operations(op_lists_by_index[i]))
             else:
                 self._moments.append(Moment(op_lists_by_index[i]))
-        self._mutated()
 
     def __copy__(self) -> 'cirq.Circuit':
         return self.copy()

Diff for: cirq-core/cirq/circuits/circuit_test.py

@@ -4553,6 +4553,80 @@ def test_freeze_is_cached():
     assert f5 is f4
 
 
+@pytest.mark.parametrize(
+    "circuit, mutate",
+    [
+        (
+            cirq.Circuit(cirq.X(cirq.q(0)), cirq.M(cirq.q(0))),
+            lambda c: c.__setitem__(0, cirq.Moment(cirq.Y(cirq.q(0)))),
+        ),
+        (cirq.Circuit(cirq.X(cirq.q(0)), cirq.M(cirq.q(0))), lambda c: c.__delitem__(0)),
+        (cirq.Circuit(cirq.X(cirq.q(0)), cirq.M(cirq.q(0))), lambda c: c.__imul__(2)),
+        (
+            cirq.Circuit(cirq.X(cirq.q(0)), cirq.M(cirq.q(0))),
+            lambda c: c.insert(1, cirq.Y(cirq.q(0))),
+        ),
+        (
+            cirq.Circuit(cirq.X(cirq.q(0)), cirq.M(cirq.q(0))),
+            lambda c: c.insert_into_range([cirq.Y(cirq.q(1)), cirq.M(cirq.q(1))], 0, 2),
+        ),
+        (
+            cirq.Circuit(cirq.X(cirq.q(0)), cirq.M(cirq.q(0))),
+            lambda c: c.insert_at_frontier([cirq.Y(cirq.q(0)), cirq.Y(cirq.q(1))], 1),
+        ),
+        (
+            cirq.Circuit(cirq.X(cirq.q(0)), cirq.M(cirq.q(0))),
+            lambda c: c.batch_replace([(0, cirq.X(cirq.q(0)), cirq.Y(cirq.q(0)))]),
+        ),
+        (
+            cirq.Circuit(cirq.X(cirq.q(0)), cirq.M(cirq.q(0), cirq.q(1))),
+            lambda c: c.batch_insert_into([(0, cirq.X(cirq.q(1)))]),
+        ),
+        (
+            cirq.Circuit(cirq.X(cirq.q(0)), cirq.M(cirq.q(0))),
+            lambda c: c.batch_insert([(1, cirq.Y(cirq.q(0)))]),
+        ),
+        (
+            cirq.Circuit(cirq.X(cirq.q(0)), cirq.M(cirq.q(0))),
+            lambda c: c.clear_operations_touching([cirq.q(0)], [0]),
+        ),
+    ],
+)
+def test_mutation_clears_cached_attributes(circuit, mutate):
+    cached_attributes = [
+        "_all_qubits",
+        "_frozen",
+        "_is_measurement",
+        "_is_parameterized",
+        "_parameter_names",
+    ]
+
+    for attr in cached_attributes:
+        assert getattr(circuit, attr) is None, f"{attr=} is not None"
+
+    # Check that attributes are cached after getting them.
+    qubits = circuit.all_qubits()
+    frozen = circuit.freeze()
+    is_measurement = cirq.is_measurement(circuit)
+    is_parameterized = cirq.is_parameterized(circuit)
+    parameter_names = cirq.parameter_names(circuit)
+
+    for attr in cached_attributes:
+        assert getattr(circuit, attr) is not None, f"{attr=} is None"
+
+    # Check that getting again returns same object.
+    assert circuit.all_qubits() is qubits
+    assert circuit.freeze() is frozen
+    assert cirq.is_measurement(circuit) is is_measurement
+    assert cirq.is_parameterized(circuit) is is_parameterized
+    assert cirq.parameter_names(circuit) is parameter_names
+
+    # Check that attributes are cleared after mutation.
+    mutate(circuit)
+    for attr in cached_attributes:
+        assert getattr(circuit, attr) is None, f"{attr=} is not None"
+
+
 def test_factorize_one_factor():
     circuit = cirq.Circuit()
     q0, q1, q2 = cirq.LineQubit.range(3)