fix ms gate equality (#6231)

* fix ms gate equality

* update test

---------

Co-authored-by: Tanuj Khattar <tanujkhattar@google.com>

cirq-core/cirq/ops/parity_gates.py

@@ -28,6 +28,7 @@
     import cirq
 
 
+@value.value_equality
 class XXPowGate(gate_features.InterchangeableQubitsGate, eigen_gate.EigenGate):
     r"""The X-parity gate, possibly raised to a power.
 
@@ -133,6 +134,7 @@ def __repr__(self) -> str:
         )
 
 
+@value.value_equality
 class YYPowGate(gate_features.InterchangeableQubitsGate, eigen_gate.EigenGate):
     r"""The Y-parity gate, possibly raised to a power.
 
@@ -237,6 +239,7 @@ def __repr__(self) -> str:
         )
 
 
+@value.value_equality
 class ZZPowGate(gate_features.InterchangeableQubitsGate, eigen_gate.EigenGate):
     r"""The Z-parity gate, possibly raised to a power.
 

cirq-core/cirq/ops/parity_gates_test.py

@@ -257,8 +257,24 @@ def test_trace_distance():
 
 def test_ms_arguments():
     eq_tester = cirq.testing.EqualsTester()
-    eq_tester.add_equality_group(cirq.ms(np.pi / 2), cirq.ops.MSGate(rads=np.pi / 2))
-    eq_tester.add_equality_group(cirq.XXPowGate(global_shift=-0.5))
+    eq_tester.add_equality_group(
+        cirq.ms(np.pi / 2), cirq.ops.MSGate(rads=np.pi / 2), cirq.XXPowGate(global_shift=-0.5)
+    )
+    eq_tester.add_equality_group(
+        cirq.ms(np.pi / 4), cirq.XXPowGate(exponent=0.5, global_shift=-0.5)
+    )
+    eq_tester.add_equality_group(cirq.XX)
+    eq_tester.add_equality_group(cirq.XX**0.5)
+
+
+def test_ms_equal_up_to_global_phase():
+    assert cirq.equal_up_to_global_phase(cirq.ms(np.pi / 2), cirq.XX)
+    assert cirq.equal_up_to_global_phase(cirq.ms(np.pi / 4), cirq.XX**0.5)
+    assert not cirq.equal_up_to_global_phase(cirq.ms(np.pi / 4), cirq.XX)
+
+    assert cirq.ms(np.pi / 2) in cirq.GateFamily(cirq.XX)
+    assert cirq.ms(np.pi / 4) in cirq.GateFamily(cirq.XX**0.5)
+    assert cirq.ms(np.pi / 4) not in cirq.GateFamily(cirq.XX)
 
 
 def test_ms_str():