Fix the format of CliffordGate repr. (#7046)

* fix the format of CliffordGate repr.

* Add unit tests for CliffordGate.__repr__()

* Check the full string of repr without calling _str_full_.

* remove test cases

* Strip trailing blanks in the expected repr(gate) string

---------

Co-authored-by: Pavol Juhas <juhas@google.com>

Author: babacry

cirq-core/cirq/ops/clifford_gate.py

@@ -433,7 +433,7 @@ def __pow__(self, exponent: float) -> 'CliffordGate':
         return CliffordGate.from_clifford_tableau(base_tableau)
 
     def __repr__(self) -> str:
-        return f"Clifford Gate with Tableau:\n {self.clifford_tableau._str_full_()}"
+        return f"Clifford Gate with Tableau:\n{self.clifford_tableau._str_full_()}"
 
     def _commutes_(
         self, other: Any, *, atol: float = 1e-8

cirq-core/cirq/ops/clifford_gate_test.py

@@ -923,7 +923,31 @@ def test_all_single_qubit_clifford_unitaries():
     assert cirq.equal_up_to_global_phase(cs[23], (i - 1j * (-x - y - z)) / 2)
 
 
+def test_clifford_gate_repr():
+    q0, q1, q2 = cirq.LineQubit.range(3)
+    assert (
+        repr(cirq.ops.CliffordGate.from_op_list([cirq.ops.X(q0), cirq.CZ(q1, q2)], [q0, q1, q2]))
+        == """Clifford Gate with Tableau:
+stable   | destable
+---------+----------
+- Z0     | + X0
++   Z1   | +   X1Z2
++     Z2 | +   Z1X2
+"""
+    )
+    assert (
+        repr(cirq.ops.CliffordGate.CNOT)
+        == """Clifford Gate with Tableau:
+stable | destable
+-------+----------
++ Z0   | + X0X1
++ Z0Z1 | +   X1
+"""
+    )
+
+
 def test_single_qubit_clifford_gate_repr():
+    # Common gates
     assert repr(cirq.ops.SingleQubitCliffordGate.X) == (
         'cirq.ops.SingleQubitCliffordGate(_clifford_tableau=cirq.CliffordTableau(1, '
         'rs=np.array([False, True]), xs=np.array([[True], [False]]), '
@@ -950,8 +974,22 @@ def test_single_qubit_clifford_gate_repr():
         'zs=np.array([[False], [True]])))'
     )
 
-    assert str(cirq.ops.SingleQubitCliffordGate.X) == (
+    assert repr(cirq.ops.SingleQubitCliffordGate.X) == (
         'cirq.ops.SingleQubitCliffordGate(_clifford_tableau=cirq.CliffordTableau(1, '
         'rs=np.array([False, True]), xs=np.array([[True], [False]]), '
         'zs=np.array([[False], [True]])))'
     )
+
+    # Other gates
+    qa = cirq.NamedQubit('a')
+    gate = cirq.ops.SingleQubitCliffordGate.from_clifford_tableau(
+        cirq.ops.CliffordGate.from_op_list(
+            [cirq.ops.PhasedXZGate(axis_phase_exponent=0.25, x_exponent=-1, z_exponent=0).on(qa)],
+            [qa],
+        ).clifford_tableau
+    )
+    assert repr(gate) == (
+        'cirq.ops.SingleQubitCliffordGate(_clifford_tableau=cirq.CliffordTableau(1, '
+        'rs=np.array([False, True]), xs=np.array([[True], [False]]), '
+        'zs=np.array([[True], [True]])))'
+    )